BitDevs Maputo

Socratic Seminar 01: Who Really Runs Bitcoin?

2026-10-17T00:00:00+00:00

Location

The event will be hosted at Hotel Onomo, Maputo

Date: October 17, 2026

Time: 09:00 to 12:00

Announcements

Join us for the first BitDevs Maputo Socratic Seminar! We will run Bitcoin Core on our own laptops and find out who really runs Bitcoin. A special thank you to our sponsor Btrust.

Bring your laptop.

Reminders

We prefer no photos and no videos during the event
Chatham House Rule
Leave the meeting space as clean as you found it
Suggest topics for the next Socratic Seminar! Where to find topics?

Topics

Opening

MC: Angela

Welcome and introduction to the Socratic format
Introduction to BitDevs Maputo and the goals of the seminar

Introduction

MC: Daniel

Introduction to Bitcoin Famba

Bitcoin Core

MC: Custódio

Download and run a Bitcoin Core node
JSON-RPC interface: the commands we will use
BIPs implemented by Bitcoin Core
Who decides the rules of Bitcoin? Developers, miners, exchanges, or the people who run a node?

Private & Public Keys

MC: Custódio

Not your keys, not your coins
Descriptors: how Core describes keys, scripts and addresses
BIP32: HD wallets
Code: key generation (key.cpp)

Addresses & Transactions

MC: Custódio

Closing & Upcoming Events

MC: Angela

Summary of the discussion
Next Socratic Seminar and community group

Seminário Socrático 01: Quem manda realmente no Bitcoin?

2026-10-17T00:00:00+00:00

Local

O evento será no Hotel Onomo, Maputo

Mapa

Data: 17 de Outubro de 2026

Horário: 09:00 às 12:00

Anúncios

Junta-te a nós no primeiro Seminário Socrático da BitDevs Maputo! Vamos correr o Bitcoin Core nos nossos laptops e descobrir quem manda realmente no Bitcoin. Um agradecimento especial ao nosso patrocinador Btrust.

Traz o teu laptop.

Lembretes

Preferimos sem fotos e sem vídeos durante o evento
Regra de Chatham House
Deixa o espaço tão limpo como o encontraste
Sugere temas para o próximo Seminário Socrático! Onde encontrar temas?

Temas

Abertura

MC: Angela

Boas-vindas e apresentação do formato socrático
Apresentação da BitDevs Maputo e dos objectivos do seminário

Apresentação

MC: Daniel

Apresentação do Bitcoin Famba

Bitcoin Core

MC: Custódio

Descarregar e correr um nó Bitcoin Core
Interface JSON-RPC: os comandos que vamos usar
BIPs implementados pelo Bitcoin Core
Quem decide as regras do Bitcoin? Programadores, mineradores, exchanges ou quem corre um nó?

Chaves Privadas e Públicas

MC: Custódio

Not your keys, not your coins
Descriptors: como o Core descreve chaves, scripts e endereços
BIP32: carteiras HD
Código: geração de chaves (key.cpp)

Entropia

MC: Custódio

Not your entropia, not your coins
Código: fonte de aleatoriedade (random.cpp)
O Core não usa BIP39: o que é realmente a tua seed?

Endereços e Transações

MC: Custódio

Encerramento e Próximos Eventos

MC: Angela

Resumo da discussão
Próximo Seminário Socrático e grupo da comunidade

Protect Your Bitcoin Like Satoshi

2026-10-16T00:00:00+00:00

Protect Your Bitcoin Like Satoshi: A Guide to Cold Storage with an Air-Gapped Laptop

Introduction and Philosophy

Bitcoin security depends on protecting the private keys that allow funds to be spent. Today, many users rely on hardware wallets such as Coldcard, Trezor, and Ledger. However, it is also possible to build a cold storage solution using a dedicated computer, auditable software, and a rigorous network isolation process.

The idea is to turn an old laptop into an air-gapped device: a computer kept physically isolated from the internet and other networks. This device is used exclusively to generate and protect private keys and sign Bitcoin transactions offline.

This approach helps users better understand Bitcoin’s security mechanisms and reduces dependence on specialized devices. However, it requires technical knowledge, careful procedures, and thorough testing before storing significant funds.

Why Consider an Air-Gapped Laptop?

1. Control Over Software and Hardware

Hardware wallets offer convenience, but they also require trust in their firmware, manufacturing process, and random number generation mechanisms.

With a dedicated computer, users can choose the operating system, verify installation files, inspect the software, and document the configuration process.

This does not automatically make a laptop more secure. Security depends on implementation quality, software provenance, entropy generation, and backup protection.

2. Privacy

Purchasing specialized devices may create commercial records linking a person to a particular product. A generic laptop may reduce this direct association, although it does not guarantee anonymity or eliminate other privacy risks.

Privacy also depends on how users manage transactions, communicate with Bitcoin nodes, and protect information associated with their wallets.

3. Technological Independence

A dedicated computer allows users to build a security process they understand and control without relying exclusively on a specific manufacturer.

However, this independence comes with responsibility: users must maintain verified backups and understand how to recover their funds if the equipment fails.

What Does Air-Gapped Mean?

An air-gapped device is a computer kept isolated from external networks, including the internet. For a rigorous security setup, isolation must be planned and verified rather than simply assumed.

The dedicated laptop serves two main purposes:

Key generation: Create private cryptographic material in a controlled environment.
Offline signing: Sign transactions without exposing private keys to an internet-connected computer.

The process can work as follows:

An online computer prepares an unsigned Bitcoin transaction.
The transaction is transferred to the offline device using a controlled transfer method.
The offline device verifies the transaction data and signs it.
The signed transaction is returned to the online computer.
The online computer broadcasts the transaction to the Bitcoin network.

Private keys remain on the offline device throughout the process. Transferred files must be handled carefully because USB drives and memory cards can introduce security risks.

Implementation Roadmap: Five Stages

Episode 1 — Hardware and Security Philosophy

Understand the principles of minimizing trust, isolation, private key protection, and long-term preservation.

Episode 2 — Communication Isolation

Identify and disable unnecessary communication interfaces, including Wi-Fi and Bluetooth. Physical component removal may be considered when appropriate, but only after understanding the equipment’s limitations.

Episode 3 — Operating System and Bitcoin Software

Install an appropriate operating system, obtain Bitcoin software from official sources, and verify the authenticity and integrity of installation files before use.

Episode 4 — Key Generation and Offline Signing

Understand entropy generation, wallet creation, and offline transaction signing. Test the entire process with small amounts before using real funds.

Episode 5 — Backups and Long-Term Preservation

Explore recovery methods, protection against physical damage, backup redundancy, and the procedures required to recover a wallet in the future.

Hardware Selection: Lenovo ThinkPad T530

One example of hardware worth investigating for this project is the Lenovo ThinkPad T530, a laptop released in 2012.

Its maintainability and replaceable components make it a potential candidate for experimentation. However, its age also requires attention to the battery, storage, memory, and overall system condition.

Before selecting a laptop, consider:

Whether communication interfaces can be disabled or removed.
Compatibility with a suitable operating system.
The ability to verify and maintain the software in use.
Firmware integrity and hardware-related risks.
The ease of creating and recovering backups.

Models such as the ThinkPad X220, X230, and T420 can also be investigated, particularly by users interested in alternative firmware. Compatibility with projects such as Coreboot or Libreboot must be verified for the exact hardware configuration.

Important: Keeping a computer offline reduces exposure to remote attacks, but it does not eliminate firmware vulnerabilities, implementation flaws, entropy problems, or physical tampering risks.

Security: What You Should Never Ignore

An air-gapped system is not an absolute security guarantee. To reduce risks:

Obtain software from official sources and verify applicable signatures or checksums.
Never introduce files or storage devices from unknown sources into the offline computer.
Never photograph recovery phrases or store them in cloud services.
Maintain protected backups and periodically verify that they can be recovered.
Test wallet recovery before storing significant amounts.
Consider a multisignature configuration when your security requirements and technical knowledge justify it.

Security also depends on recoverability. A highly isolated wallet is of little practical use if its recovery phrase is lost, potentially resulting in permanent loss of access to the bitcoins.

Conclusion

Building a cold storage solution with a dedicated laptop is an opportunity to study cryptography, operational security, and how Bitcoin transactions work.

The goal is not simply to replace a hardware wallet with an old computer. It is to understand the risks, verify the components being used, and establish a generation, signing, and recovery process that can be audited and tested.

The best solution is one whose security you understand, whose procedures you can execute correctly, and whose recovery process you can demonstrate before trusting it with your bitcoins.

Proteja o seu Bitcoin como Satoshi

2026-10-16T00:00:00+00:00

Proteja o seu Bitcoin como Satoshi: Guia de Cold Storage com Portátil Air-Gapped

Introdução e filosofia

A segurança do Bitcoin depende da proteção das chaves privadas que permitem movimentar os fundos. Atualmente, muitos utilizadores recorrem a carteiras de hardware, como Coldcard, Trezor e Ledger. No entanto, também é possível construir uma solução de cold storage utilizando um computador dedicado, software auditável e um processo rigoroso de isolamento de redes.

A ideia é transformar um portátil antigo num dispositivo air-gapped, ou seja, um computador mantido fisicamente isolado da internet e de outras redes. Este dispositivo é utilizado exclusivamente para gerar e proteger chaves privadas e assinar transações Bitcoin offline.

Esta abordagem permite compreender melhor os mecanismos de segurança do Bitcoin e reduzir a dependência de dispositivos especializados. Contudo, exige conhecimentos técnicos, procedimentos cuidadosos e testes antes de guardar fundos significativos.

Por que considerar um portátil air-gapped?

1. Controlo sobre o software e o hardware

Uma carteira de hardware oferece conveniência, mas também exige confiança no seu firmware, no processo de fabrico e nos mecanismos utilizados para gerar números aleatórios.

Com um computador dedicado, o utilizador pode escolher o sistema operativo, verificar os ficheiros de instalação, analisar o software e documentar o processo de configuração.

Isto não significa que um portátil seja automaticamente mais seguro. A segurança depende da qualidade da implementação, da origem do software, da geração de entropia e da proteção das cópias de segurança.

2. Privacidade

A aquisição de dispositivos especializados pode criar registos comerciais que associam uma pessoa a determinado produto. Um portátil genérico pode reduzir essa associação direta, embora não garanta anonimato nem elimine outros riscos de privacidade.

A privacidade também depende da forma como o utilizador gere as suas transações, comunica com nós Bitcoin e protege as informações relacionadas com a sua carteira.

3. Independência tecnológica

Um computador dedicado permite construir um processo de segurança compreendido e controlado pelo próprio utilizador, sem depender exclusivamente de um fabricante específico.

Esta independência exige, porém, responsabilidade: o utilizador deve manter cópias de segurança verificadas e compreender como recuperar os fundos em caso de falha do equipamento.

O que significa air-gapped?

Um dispositivo air-gapped é um computador mantido isolado de redes externas, incluindo a internet. Para uma configuração de segurança rigorosa, o isolamento deve ser planeado e verificado, não apenas presumido.

O portátil dedicado desempenha duas funções principais:

Geração de chaves: criar material criptográfico privado num ambiente controlado.
Assinatura offline: assinar transações sem expor as chaves privadas a um computador ligado à internet.

O processo pode funcionar da seguinte forma:

Um computador online prepara uma transação Bitcoin sem assinatura.
A transação é transferida para o dispositivo offline através de um meio de transferência controlado.
O dispositivo offline verifica os dados e assina a transação.
A transação assinada regressa ao computador online.
O computador online transmite a transação à rede Bitcoin.

As chaves privadas permanecem no dispositivo offline durante todo o processo. Os dados transferidos devem ser tratados com cuidado, porque um meio USB ou cartão de memória também pode introduzir riscos de segurança.

Roteiro de implementação: cinco etapas

Episódio 1 — Hardware e filosofia de segurança

Compreender os princípios de minimização da confiança, isolamento, proteção das chaves privadas e preservação de longo prazo.

Episódio 2 — Isolamento das comunicações

Identificar e desativar as interfaces de comunicação desnecessárias, incluindo Wi-Fi e Bluetooth. A remoção física de componentes pode ser considerada, mas deve ser realizada apenas quando apropriada e depois de compreender as limitações do equipamento.

Episódio 3 — Sistema operativo e software Bitcoin

Instalar um sistema operativo apropriado, obter o software Bitcoin de fontes oficiais e verificar a autenticidade e integridade dos ficheiros antes de os utilizar.

Episódio 4 — Geração de chaves e assinatura offline

Compreender a geração de entropia, a criação de carteiras e o processo de assinatura de transações offline. Antes de utilizar fundos reais, testar todo o fluxo com pequenas quantias.

Episódio 5 — Cópias de segurança e preservação de longo prazo

Estudar os métodos de recuperação, a proteção contra danos físicos, a redundância das cópias de segurança e os procedimentos necessários para recuperar a carteira no futuro.

Escolha do hardware: Lenovo ThinkPad T530

Um exemplo de equipamento que pode ser estudado para este projeto é o Lenovo ThinkPad T530, um portátil lançado em 2012.

Entre as características relevantes estão a possibilidade de manutenção e a disponibilidade de componentes substituíveis. No entanto, a idade do equipamento também exige atenção à bateria, ao armazenamento, à memória e ao estado geral do sistema.

Antes de escolher um portátil, é importante considerar:

A possibilidade de desativar ou remover interfaces de comunicação.
A compatibilidade com um sistema operativo adequado.
A capacidade de verificar e manter o software utilizado.
A integridade do firmware e os riscos associados ao hardware.
A facilidade de criar e recuperar cópias de segurança.

Modelos como o ThinkPad X220, X230 e T420 também podem ser investigados, especialmente por quem pretende estudar firmware alternativo. A compatibilidade com projetos como Coreboot ou Libreboot deve ser confirmada para a configuração exata do equipamento.

Importante: manter um computador offline reduz a exposição a ataques remotos, mas não elimina vulnerabilidades de firmware, falhas de implementação, problemas de entropia ou riscos de manipulação física.

Segurança: o que não deves ignorar

Um sistema air-gapped não é uma garantia absoluta de segurança. Para reduzir os riscos:

Obtém o software a partir de fontes oficiais e verifica as assinaturas ou somas de verificação aplicáveis.
Não introduzas no dispositivo offline ficheiros ou suportes de origem desconhecida.
Nunca fotografes nem guardes frases de recuperação em serviços na nuvem.
Mantém cópias de segurança protegidas e verifica periodicamente se podem ser recuperadas.
Testa a recuperação da carteira antes de guardar valores significativos.
Considera uma configuração multisig quando as necessidades de segurança e o nível de conhecimento o justificarem.

A segurança também depende da capacidade de recuperar os fundos. Uma carteira muito bem isolada, mas cuja frase de recuperação se perde, pode resultar na perda definitiva do acesso aos bitcoins.

Conclusão

Construir uma solução de cold storage com um portátil dedicado é uma oportunidade para estudar criptografia, segurança operacional e o funcionamento das transações Bitcoin.

O objetivo não é simplesmente substituir uma carteira de hardware por um computador antigo. É compreender os riscos, verificar os componentes utilizados e criar um processo de geração, assinatura e recuperação que possa ser auditado e testado.

A melhor solução será aquela cuja segurança compreendes, cujos procedimentos consegues executar corretamente e cuja recuperação consegues demonstrar antes de confiar nela os teus bitcoins.

The Magic of Key Multiplication: Understanding BIP32 in Bitcoin

2026-10-15T00:00:00+00:00

The Magic of Key Multiplication: Understanding BIP32 in Bitcoin

Introduction

Many Bitcoin users are familiar with the sequence of 12 or 24 English words used to back up digital wallets through BIP39. However, to understand how these words can restore a wallet’s keys and addresses, it is important to take a step back and understand BIP32 (Bitcoin Improvement Proposal 32).

Inspired by the technical lesson by Tiago Salem, titled “A Magia da Multiplicação de Chaves — BIP32”, this article explores how elliptic curve mathematics enables the creation of Hierarchical Deterministic (HD) wallets, eliminating the need to manage thousands of independent private keys.

What Is a Bitcoin Improvement Proposal (BIP)?

A Bitcoin Improvement Proposal (BIP) is a document that describes a proposed standard, process, or improvement related to Bitcoin.

Bitcoin development emphasizes careful review and community discussion. BIPs provide a structured way to document technical ideas, discuss their implications, and coordinate implementations.

Introduced in 2012, BIP32 established a standard for deriving a hierarchy of cryptographic keys from a single master seed, making wallet management and backup significantly more practical.

The Evolution of Bitcoin Key Management

1. The Cryptographic Foundation

Bitcoin uses elliptic curve cryptography based on the secp256k1 curve to generate public and private keys.

Private key: A secret integer represented using 32 bytes. It authorizes the signing of transactions that spend the associated funds.
Public key: A point on the elliptic curve represented by coordinates ((x, y)).
Bitcoin address: An encoded identifier derived through a specific process involving public key data, depending on the address type.

The public key is calculated from the private key using elliptic curve multiplication:

[ P = kG ]

Where:

(k) is the private key.
(G) is the generator point of the curve.
(P) is the corresponding public key.

Calculating (P) from (k) is computationally practical. Recovering (k) from (P), however, is considered computationally infeasible with current classical computing methods when secure parameters are used. This is the elliptic curve discrete logarithm problem.

2. The Original Problem: Address Reuse and Endless Backups

Bitcoin users are encouraged to avoid address reuse to improve financial privacy.

Before hierarchical deterministic wallets became widespread, wallet software could generate independent random private keys for new addresses. Managing these keys created several challenges:

Backup complexity: Users needed to ensure that newly generated keys were included in their backups. A backup that did not contain a required key could result in permanent loss of access to funds.
Operational limitations: Businesses and payment systems needed a way to generate new receiving addresses without exposing private keys to online servers.
Recovery difficulties: Managing a growing collection of unrelated keys made wallet restoration more complicated.

BIP32 addressed these problems by introducing a standardized hierarchy of related keys.

The BIP32 Solution: Hierarchical Deterministic Wallets

BIP32 introduced a system in which a master key and a chain code can be used to derive a hierarchy of child keys.

Instead of independently generating and backing up every private key, a wallet can derive many related keys from a single master seed.

This structure can be represented as a tree:

Master key: The root of the hierarchy.
Child keys: Keys derived from a parent key.
Grandchild keys: Keys derived from child keys.
Branches: Separate paths used for different accounts, addresses, or purposes.

The derivation process is deterministic: given the same master seed and derivation path, a wallet can reproduce the same keys.

The Mathematics Behind Public Key Derivation

The key mathematical property comes from elliptic curve group operations.

A public key is calculated as:

[ P = kG ]

Suppose a new private key is calculated by adding a scalar (t) to the original private key:

[ k’ = k + t \pmod n ]

The corresponding public key is:

[ P’ = k’G ]

Substituting the private key expression gives:

[ P’ = (k+t)G ]

Using the properties of elliptic curve group operations:

[ P’ = kG+tG ]

Since (P=kG), we obtain:

[ \boxed{P’=P+tG} ]

This means the new public key can be calculated using the original public key and the corresponding public derivation data, without revealing the original private key.

An important distinction: BIP32 does not simply multiply a private key by an arbitrary factor. It uses a cryptographic derivation function based on HMAC-SHA512, together with elliptic curve operations and a chain code.

For a non-hardened child key, the simplified mathematical relationship is:

[ k_i = (\operatorname{parse}{256}(I_L)+k{\text{par}})\bmod n ]

And the corresponding public key is:

[ K_i = \operatorname{parse}{256}(I_L)G+K{\text{par}} ]

Here, (I_L) is derived from the HMAC-SHA512 output, (k_{\text{par}}) is the parent private key, (K_{\text{par}}) is the parent public key, and (n) is the order of the generator point.

The chain code and derivation index determine the derivation data. This is what makes BIP32 derivation structured and reproducible rather than a simple arbitrary multiplication.

A Practical Demonstration in Python

A mathematical demonstration can help illustrate the relationship between private and public keys.

Using a suitable secp256k1 library, the experiment can follow these steps:

Generate an initial private key (k).
Calculate its public key (P=kG).
Choose a valid scalar (t).
Calculate a new private key (k’=(k+t)\bmod n).
Calculate the new public key directly from (k’).
Independently calculate (P’=P+tG).
Compare both resulting public keys.

The two public keys should match, provided the scalar values are valid and the operations are implemented correctly.

This experiment illustrates the mathematical property behind non-hardened public key derivation. It is not, by itself, a complete BIP32 implementation, because actual BIP32 derivation also requires HMAC-SHA512, chain codes, serialization, and derivation indexes.

For real Bitcoin wallets, use established implementations rather than experimental code to generate or manage private keys.

Extended Keys: `xprv` and `xpub`

BIP32 defines serialized extended keys that combine key material with a chain code and metadata required for derivation.

`xprv` — Extended Private Key

An extended private key contains a private key and its associated chain code, together with derivation metadata.

It can derive private and public descendants, subject to the derivation rules.

Anyone who obtains an extended private key can generally derive the private keys within its corresponding subtree and spend the associated funds.

`xpub` — Extended Public Key

An extended public key contains a public key and its chain code, along with derivation metadata.

It allows the derivation of non-hardened public descendants without access to private keys. This makes it useful for watch-only wallets, payment systems, and online servers that need to generate receiving addresses without being able to sign transactions.

However, an xpub is not harmless public information.

Privacy and security warning:

Sharing an xpub can expose a substantial portion of a wallet’s address structure and transaction activity.
An xpub alone does not normally allow an attacker to spend funds.
Combining a parent extended public key with a corresponding non-hardened child private key can reveal the parent private key under the applicable BIP32 derivation conditions.

For these reasons, extended public keys should be shared only when necessary and with a clear understanding of the privacy implications.

BIP32 and BIP39: Understanding the Difference

BIP32 and BIP39 solve related but different problems.

BIP32 defines hierarchical deterministic key derivation: how a master key can produce a structured tree of child keys.

BIP39 defines a mnemonic system that converts computer-generated entropy into a sequence of words and uses that mnemonic, together with an optional passphrase, to derive a seed.

The relationship can be summarized as follows:

Entropy is generated securely.
BIP39 converts the entropy into a mnemonic phrase.
The mnemonic and optional passphrase are processed to produce a seed.
BIP32 uses the seed to generate the master key and chain code.
Child keys are derived according to specified paths.

A recovery phrase is therefore not simply a readable version of an xprv. It is an input used to reconstruct the seed from which the wallet’s key hierarchy can be derived.

Conclusion

BIP32 is a foundational standard for modern deterministic Bitcoin wallets. By combining cryptographic derivation with the mathematical properties of elliptic curves, it makes key management more scalable and enables useful separation between public address generation and private transaction signing.

Understanding the relationship between private keys, public keys, chain codes, xprv, and xpub is essential for anyone studying Bitcoin development, wallet architecture, or cryptographic security.

The most important lesson is that BIP32 is not merely a trick involving key multiplication. It is a carefully specified derivation system that makes deterministic wallet recovery and non-hardened public key derivation possible while preserving the secrecy of private keys under the intended security assumptions.

A Magia da Multiplicação de Chaves: Entendendo a BIP32

2026-10-15T00:00:00+00:00

A Magia da Multiplicação de Chaves: Entendendo a BIP32 no Bitcoin

Introdução

Muitos utilizadores de Bitcoin estão familiarizados com a sequência de 12 ou 24 palavras utilizada para recuperar uma carteira digital através da BIP39. Contudo, para compreender como essas palavras permitem recuperar as chaves e os endereços de uma carteira, é importante conhecer a BIP32 (Bitcoin Improvement Proposal 32).

Inspirado na aula técnica de Tiago Salem, intitulada “A Magia da Multiplicação de Chaves — BIP32”, este artigo explora como a matemática das curvas elípticas permite criar carteiras determinísticas hierárquicas (Hierarchical Deterministic Wallets ou HD Wallets), eliminando a necessidade de gerir milhares de chaves privadas independentes.

O que é uma BIP (Bitcoin Improvement Proposal)?

Uma Bitcoin Improvement Proposal (BIP) é um documento que descreve uma proposta de padrão, processo ou melhoria relacionada com o Bitcoin.

O desenvolvimento do Bitcoin privilegia uma análise cuidadosa e a discussão comunitária. As BIPs permitem documentar ideias técnicas, discutir as suas implicações e coordenar as respetivas implementações.

Proposta em 2012, a BIP32 estabeleceu um padrão para derivar uma hierarquia de chaves criptográficas a partir de uma única semente mestre, tornando a gestão e a recuperação de carteiras muito mais práticas.

A evolução da gestão de chaves no Bitcoin

1. A base criptográfica

O Bitcoin utiliza criptografia de curvas elípticas baseada na curva secp256k1 para gerar chaves públicas e privadas.

Chave privada: Um número secreto representado por 32 bytes. Permite assinar transações que movimentam os fundos associados.
Chave pública: Um ponto na curva elíptica, representado pelas coordenadas ((x, y)).
Endereço Bitcoin: Um identificador codificado, derivado através de um processo específico que utiliza dados da chave pública, dependendo do tipo de endereço.

A chave pública é calculada a partir da chave privada através da multiplicação de pontos na curva elíptica:

[ P = kG ]

Em que:

(k) é a chave privada.
(G) é o ponto gerador da curva.
(P) é a chave pública correspondente.

Calcular (P) a partir de (k) é computacionalmente viável. Recuperar (k) a partir de (P), por outro lado, é considerado computacionalmente inviável com os métodos clássicos atuais, quando são utilizados parâmetros seguros. Este problema é conhecido como o problema do logaritmo discreto em curvas elípticas.

2. O problema original: reutilização de endereços e cópias de segurança infinitas

Os utilizadores de Bitcoin são incentivados a evitar a reutilização de endereços para melhorar a privacidade financeira.

Antes da popularização das carteiras determinísticas hierárquicas, os programas de carteira podiam gerar chaves privadas aleatórias e independentes para novos endereços. A gestão dessas chaves apresentava vários desafios:

Complexidade das cópias de segurança: Era necessário garantir que as novas chaves fossem incluídas nas cópias de segurança. Uma cópia que não contivesse uma chave necessária poderia provocar a perda definitiva do acesso aos fundos.
Limitações operacionais: Empresas e sistemas de pagamento precisavam de uma forma de gerar novos endereços de recebimento sem expor as chaves privadas aos servidores online.
Dificuldades de recuperação: A gestão de uma coleção crescente de chaves independentes tornava a recuperação da carteira mais complicada.

A BIP32 resolveu estes problemas ao introduzir um padrão para derivar chaves relacionadas de forma hierárquica.

A solução BIP32: carteiras determinísticas hierárquicas

A BIP32 introduziu um sistema em que uma chave mestre e um código de cadeia (chain code) permitem derivar uma hierarquia de chaves filhas.

Em vez de gerar e guardar uma cópia de segurança independente para cada chave privada, uma carteira pode derivar muitas chaves relacionadas a partir de uma única semente mestre.

Esta estrutura pode ser representada como uma árvore:

Chave mestre: A raiz da hierarquia.
Chaves filhas: Chaves derivadas de uma chave principal.
Chaves netas: Chaves derivadas das chaves filhas.
Ramos: Caminhos separados para diferentes contas, endereços ou finalidades.

O processo de derivação é determinístico: utilizando a mesma semente mestre e o mesmo caminho de derivação, uma carteira consegue reproduzir as mesmas chaves.

A matemática por trás da derivação de chaves públicas

A propriedade matemática central resulta das operações de grupo das curvas elípticas.

Uma chave pública é calculada através da expressão:

[ P = kG ]

Suponhamos que uma nova chave privada é calculada adicionando um escalar (t) à chave privada original:

[ k’ = (k+t)\bmod n ]

A chave pública correspondente é:

[ P’ = k’G ]

Substituindo a expressão da chave privada:

[ P’ = (k+t)G ]

Aplicando as propriedades das operações de grupo das curvas elípticas:

[ P’ = kG+tG ]

Como (P=kG), obtemos:

[ \boxed{P’=P+tG} ]

Isto significa que a nova chave pública pode ser calculada utilizando a chave pública original e os dados correspondentes da derivação, sem revelar a chave privada original.

Uma distinção importante: a BIP32 não consiste simplesmente em multiplicar uma chave privada por um fator arbitrário. Utiliza uma função criptográfica baseada em HMAC-SHA512, juntamente com operações de curvas elípticas e um código de cadeia.

Para uma chave filha não endurecida (non-hardened), a relação matemática simplificada é:

[ k_i=(\operatorname{parse}{256}(I_L)+k{\text{par}})\bmod n ]

A chave pública correspondente é:

[ K_i=\operatorname{parse}{256}(I_L)G+K{\text{par}} ]

Neste contexto:

(I_L) é derivado da saída de HMAC-SHA512.
(k_{\text{par}}) é a chave privada da chave principal.
(K_{\text{par}}) é a chave pública da chave principal.
(n) é a ordem do ponto gerador.

O código de cadeia e o índice de derivação determinam os dados utilizados no processo. É isto que torna a derivação BIP32 estruturada e reproduzível, em vez de uma simples multiplicação arbitrária.

Demonstração prática em Python

Uma demonstração matemática pode ajudar a compreender a relação entre chaves privadas e públicas.

Utilizando uma biblioteca apropriada para secp256k1, a experiência pode seguir estes passos:

Gerar uma chave privada inicial (k).
Calcular a respetiva chave pública (P=kG).
Escolher um escalar válido (t).
Calcular uma nova chave privada (k’=(k+t)\bmod n).
Calcular a nova chave pública diretamente a partir de (k’).
Calcular, de forma independente, (P’=P+tG).
Comparar as duas chaves públicas obtidas.

As duas chaves públicas devem coincidir, desde que os valores sejam válidos e as operações estejam corretamente implementadas.

Esta experiência demonstra a propriedade matemática que permite a derivação pública não endurecida. Contudo, não constitui, por si só, uma implementação completa da BIP32, porque a derivação real também exige HMAC-SHA512, códigos de cadeia, serialização e índices de derivação.

Para carteiras Bitcoin reais, utiliza implementações estabelecidas em vez de código experimental para gerar ou gerir chaves privadas.

Chaves estendidas: `xprv` e `xpub`

A BIP32 define chaves estendidas serializadas que combinam material criptográfico com um código de cadeia e metadados necessários à derivação.

`xprv` — Chave privada estendida

Uma chave privada estendida contém uma chave privada e o respetivo código de cadeia, juntamente com metadados de derivação.

Permite derivar chaves privadas e públicas descendentes, respeitando as regras de derivação.

Quem obtiver uma chave privada estendida pode, em geral, derivar as chaves privadas da subárvore correspondente e movimentar os fundos associados.

`xpub` — Chave pública estendida

Uma chave pública estendida contém uma chave pública e o respetivo código de cadeia, além dos metadados de derivação.

Permite derivar chaves públicas descendentes não endurecidas sem acesso às chaves privadas. Esta funcionalidade é útil para carteiras de consulta (watch-only), sistemas de pagamento e servidores online que precisam de gerar endereços de recebimento sem poder assinar transações.

No entanto, uma xpub não deve ser considerada informação pública inofensiva.

Aviso de privacidade e segurança:

Partilhar uma xpub pode expor uma parte significativa da estrutura de endereços e da atividade financeira de uma carteira.
Uma xpub, por si só, normalmente não permite movimentar fundos.
Combinar uma chave pública estendida principal com a chave privada de uma filha não endurecida correspondente pode permitir recuperar a chave privada principal, nas condições de derivação aplicáveis da BIP32.

Por estes motivos, as chaves públicas estendidas devem ser partilhadas apenas quando necessário e com plena compreensão das implicações para a privacidade.

BIP32 e BIP39: qual é a diferença?

A BIP32 e a BIP39 resolvem problemas relacionados, mas diferentes.

A BIP32 define a derivação hierárquica determinística de chaves: como uma chave mestre pode produzir uma árvore estruturada de chaves filhas.

A BIP39 define um sistema mnemónico que converte entropia gerada por computador numa sequência de palavras e utiliza essa sequência, juntamente com uma eventual frase-passe, para derivar uma semente.

A relação entre ambas pode ser resumida da seguinte forma:

A entropia é gerada de forma segura.
A BIP39 converte essa entropia numa frase mnemónica.
A frase mnemónica e a eventual frase-passe são processadas para produzir uma semente.
A BIP32 utiliza a semente para gerar a chave mestre e o código de cadeia.
As chaves filhas são derivadas de acordo com os caminhos especificados.

Uma frase de recuperação não é simplesmente uma versão legível de uma xprv. É uma entrada utilizada para reconstruir a semente a partir da qual a hierarquia de chaves da carteira pode ser derivada.

Conclusão

A BIP32 é um padrão fundamental para as carteiras determinísticas modernas de Bitcoin. Ao combinar derivação criptográfica com as propriedades matemáticas das curvas elípticas, torna a gestão de chaves mais escalável e permite separar a geração de endereços públicos da assinatura privada de transações.

Compreender a relação entre chaves privadas, chaves públicas, códigos de cadeia, xprv e xpub é essencial para quem estuda desenvolvimento Bitcoin, arquitetura de carteiras ou segurança criptográfica.

A principal lição é que a BIP32 não é apenas um truque de multiplicação de chaves. É um sistema de derivação cuidadosamente especificado que permite recuperar carteiras determinísticas e derivar chaves públicas não endurecidas, preservando o segredo das chaves privadas sob as condições de segurança previstas.

Advanced Transfers and Security in Bitcoin

2026-10-14T00:00:00+00:00

Advanced Transfers and Security

In the three previous articles of the Bitcoin Transfers series, we explored everything from the basic anatomy of a transaction to more efficient sending strategies, always with a practical emphasis on using Bitcoin Core on test networks. Now we move forward: beyond moving bitcoin correctly and cheaply, it is time to think about how to strengthen the security of every transfer.

This step is essential because, in the Bitcoin ecosystem, protection does not depend only on safeguarding the private key. The concept of defense in depth shows that real security emerges when we build several barriers: from key generation to the very way we structure transactions. Features such as multisig and timelocks allow us to create operations that resist loss, theft, or unauthorized access, offering resilience even in failure scenarios.

In this article, we will see how to apply each of these techniques, combining theory and practice so that your transfers not only happen, but are more robust and versatile. First, let’s understand PSBTs (Partially Signed Bitcoin Transactions), which are fundamental for using these advanced features.

PSBT – Partially Signed Transactions

A PSBT is a standard defined in BIP174 that allows transactions to be created, shared, and signed collaboratively.

It clearly separates the stages:

Raw transaction creation: whoever selects the UTXOs and defines the destinations.
Signing: each participant signs only their part, on their own device.
Finalization/Broadcast: final assembly and submission to the network.

This ensures that no single device needs all the keys or full internet access, which is essential for multisig, hardware wallets, or air-gapped setups.

Basic commands in Bitcoin Core:

Step	Command
Create a PSBT with defined inputs/outputs	`walletcreatefundedpsbt`
Sign partially	`walletprocesspsbt`
Combine several PSBTs (multiple signers)	`combinepsbt`
Finalize (produces broadcastable hex)	`finalizepsbt`
Send	`sendrawtransaction`

A PSBT is useful even with a single signer when you separate environments: create the transaction on one machine and sign it on another (secure/offline).

Let’s go through an example in Bitcoin Core.

0) Prerequisites

You already have a wallet with a balance on signet.

1) Create the PSBT (selects UTXOs and defines outputs)

bitcoin-cli -datadir="." walletcreatefundedpsbt \
  '[]' '[{"tb1q2tygw0rd24cgrrj9dajqrh398clxucnhdwlxew":0.0001}]' \
  0 '{"subtractFeeFromOutputs":[0]}' true
{
  "psbt": "cHNidP8BAHECAAAAAXT7uaRFVyzfv8vbDqsOc4AWZzxAoX0S...(shortened, same as the original)...AAAAA=",
  "fee": 0.00001410,
  "changepos": 1
}

2) Sign partially (in the same wallet)

bitcoin-cli -datadir="." walletprocesspsbt "cHNidP8BAHECAAAAAXT7uaRFVyzfv8vbDqsOc4AWZzxAoX0S...(shortened)..."
{
  "psbt": "cHNidP8BAHECAAAAAXT7uaRFVyzfv8vbDqsOc4AWZzxAoX0S...(shortened)...",
  "complete": true,
  "hex": "0200000000010174fbb9a445572cdfbfcbdb0eab0e738016673c...(shortened)...00000000"
}

walletprocesspsbt adds the signatures that the wallet is able to produce. In a regular (non-multisig) wallet, this leaves complete=true.

Explaining the fields the command returns:

psbt

This is the partially signed transaction (still in PSBT format, base64).
It is useful if you were going to pass it to another signer or wanted to store the file.
If complete were false, this would be the value to send to the next participant or to use in finalizepsbt.

complete

true means that all required signatures have already been added.
If it were false, you would keep circulating the PSBT among the parties or run combinepsbt, etc.

hex

This is the final Bitcoin transaction, already serialized (raw hex) and ready for the network.
When complete is true, Core already hands you this hex, which can be broadcast right away.

3) Finalize and broadcast

Since complete = true, there is no need to call finalizepsbt. Just take the hex value and broadcast it:

bitcoin-cli -datadir="." sendrawtransaction "0200000000010174fbb9a445572cdfbfcbdb0eab0e738016673c...(shortened)...00000000"
# a1a93c02cfb449040677950d1abf33f57c923273d5f091c942c08d229e638ce4

If complete = false, we would use the returned "psbt":

bitcoin-cli -datadir="." finalizepsbt "<SIGNED_PSBT>"

This command would produce the final hex to be broadcast.

Multisig

Multisig is a custody scheme in Bitcoin in which a spend is only valid when a predefined minimum number of keys, among several participants, sign the transaction, such as “2-of-3” or “3-of-5”, increasing security and allowing shared control.

Advantages:

Resistance to theft/loss: 1 compromised key cannot spend the funds (in 2-of-3); losing 1 key still allows recovery.
Inheritance/backup: keys distributed among different people/vaults.
Governance: approval policies (m-of-n) for companies/DAOs.

Let’s look at a practical example in Bitcoin Core:

1) Create three wallets (participants)

bitcoin-cli -datadir="." createwallet carteira1 true true "" true true
bitcoin-cli -datadir="." createwallet carteira2 true true "" true true
bitcoin-cli -datadir="." createwallet carteira3 true true "" true true

We create wallets with private keys and with descriptors. Avoid blank=true and disable_private_keys=true so you don’t end up with “empty” wallets.

2) Get the xpubs (with fingerprint/derivation)

For each wallet, list the public descriptors and copy the receiving (…/0/*) and change (…/1/*) lines:

bitcoin-cli -datadir="." -rpcwallet=carteira1 listdescriptors
{
  "wallet_name": "carteira1",
  "descriptors": [
    ...,
    {
      "desc": "wpkh([ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/0/*)#jr2a4z9x",
      "timestamp": 1758650612,
      "active": true,
      "internal": false,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    },
    {
      "desc": "wpkh([ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/1/*)#rh0ugh47",
      "timestamp": 1758650613,
      "active": true,
      "internal": true,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    }
  ]
}

bitcoin-cli -datadir="." -rpcwallet=carteira2 listdescriptors
{
 ...,
    {
      "desc": "wpkh([1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/0/*)#k32vf2uu",
      "timestamp": 1758650639,
      "active": true,
      "internal": false,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    },
    {
      "desc": "wpkh([1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/1/*)#890d5lvy",
      "timestamp": 1758650640,
      "active": true,
      "internal": true,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    }
  ]
}

bitcoin-cli -datadir="." -rpcwallet=carteira3 listdescriptors
{
  "wallet_name": "carteira3",
  "descriptors": [
    ...,
    {
      "desc": "wpkh([fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/0/*)#5szljz27",
      "timestamp": 1758650645,
      "active": true,
      "internal": false,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    },
    {
      "desc": "wpkh([fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/1/*)#9y870h6x",
      "timestamp": 1758650645,
      "active": true,
      "internal": true,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    }
  ]
}

What to copy: the public descriptors for receiving (…/0/*) and change (…/1/*). They carry the fingerprint + path (e.g., [ba39c771/84h/1h/0h]tpub.../0/*), which is essential for building the multisig correctly.

Address standard: the examples use the 84h/1h/0h derivation (Bech32, P2WPKH for singlesig). In multisig, we will combine them into P2WSH (wsh(sortedmulti(...))).

3) Create the multisig wallet (watch-only) and import the multisig descriptors (receiving and change)

Why “watch-only”? This wallet sees UTXOs, generates addresses, and creates PSBTs, but it has no private keys; the signatures happen in the participant wallets (carteira1, 2, and 3).

bitcoin-cli -datadir="." createwallet multisig-2of3 true true "" true true
{
  "name": "multisig-2of3",
  "warnings": [
    "Empty string given as passphrase, wallet will not be encrypted."
  ]
}

bitcoin-cli -datadir="." -rpcwallet=multisig-2of3 importdescriptors [{\"desc\":\"wsh(sortedmulti(2,[ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/0/*,[1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/0/*,[fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/0/*))#ed8gy0hl\",\"active\":true,\"timestamp\":\"now\"},{\"desc\":\"wsh(sortedmulti(2,[ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/1/*,[1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/1/*,[fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/1/*))#tcmu8qku\",\"active\":true,\"internal\":true,\"timestamp\":\"now\"}]
[
  {
    "success": true,
    "warnings": [
      "Range not given, using default keypool range"
    ]
  },
  {
    "success": true,
    "warnings": [
      "Range not given, using default keypool range"
    ]
  }
]

sortedmulti: guarantees a deterministic ordering of the keys (regardless of input order), avoiding different addresses for the same set of keys. The “Range not given” warning only tells you that Core will use the default range 0–999 to generate addresses. For most cases, that is fine.

4) Receive funds into the multisig

Generate a new address for this new multisig wallet:

bitcoin-cli -datadir="." -rpcwallet=multisig-2of3 getnewaddress
# tb1qrlwt49k9hqgj7m3rlc4elfj3fxe96l93zz9ez5209z8uskrqg7yqhl3v88

Send some sats to the generated address (via a signet faucet). Wait for 1+ confirmations.

5) Create the spending PSBT (in the multisig wallet)

bitcoin-cli -datadir="." -rpcwallet=multisig-2of3 walletcreatefundedpsbt "[]" "[{\"tb1qqu7d6zmh5mpf07xd7t9aehe0re63hfqk2wh2ew6045zc5svshphq7j4eek\":0.00001}]" 0 "{\"subtractFeeFromOutputs\":[0]}" true
{
  "psbt": "cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZ...(shortened, same as the original)...AAAAAA==",
  "fee": 0.00000201,
  "changepos": 0
}

walletcreatefundedpsbt selects UTXOs, builds the transaction, calculates the fee, and returns a PSBT with the metadata needed for signing.

subtractFeeFromOutputs: if set to output index 0, the fee is “deducted” from that output (useful for sending “whatever is left” without adjusting manually).

6) Sign in two wallets (Carteira1 and Carteira2, separately)

bitcoin-cli -datadir="." -rpcwallet=carteira1 walletprocesspsbt "cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZ...(shortened, the original PSBT from step 5)..."
{
  "psbt": "cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZ...(shortened, PSBT with carteira1's signature)...",
  "complete": false
}

bitcoin-cli -datadir="." -rpcwallet=carteira2 walletprocesspsbt "cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZ...(shortened, the original PSBT from step 5)..."
{
  "psbt": "cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZ...(shortened, PSBT with carteira2's signature)...",
  "complete": false
}

Each participant signs with walletprocesspsbt.

Sequential vs. parallel:

Sequential: the output of carteira1 (a psbt already holding 1 signature) goes into carteira2 → it usually comes back with complete: true.
Parallel (the one we used in this example): each signer signs the same original PSBT, and then you combine them (next step).

7) Combine the 2 signed PSBTs

bitcoin-cli -datadir="." combinepsbt "[\"<PSBT_SIGNED_BY_CARTEIRA1>\",\"<PSBT_SIGNED_BY_CARTEIRA2>\"]"
# cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZ...(shortened, combined PSBT)...

When to use it: if the signers signed in parallel (each took the original PSBT).

Expected result: the combined PSBT should already contain the 2 required signatures (2-of-3).

8) Finalize and broadcast

bitcoin-cli -datadir="." finalizepsbt "<COMBINED_PSBT>"
{
  "hex": "02000000000101b00b0c0982cda2e99862ccdc7a2c5ceba8769d37067cd9...(shortened)...53ae00000000",
  "complete": true
}

finalizepsbt: validates the script, assembles the witness, and returns the hex ready for broadcast.

Finally, the sendrawtransaction command publishes the transaction to the network.

bitcoin-cli -datadir="." sendrawtransaction "02000000000101b00b0c0982cda2e99862ccdc7a2c5ceba8769d37067cd9...(shortened)...53ae00000000"
# af5f0813b622d6a21389af6cecbe9d5098d71cdee814e7ba70fcbe0a7d1ce407

Notice, in the mempool, that this is a 2-of-3 multisig transaction:

Timelocks

In Bitcoin, timelock is the generic name for mechanisms that determine when a transaction or a given UTXO can be spent. Instead of merely requiring a valid signature, the protocol also checks time or block height, creating “mandatory waiting” conditions.

There are two main forms.

nLockTime: a field inside the transaction itself that defines the minimum block (or a timestamp) from which the network accepts including it in a block. It is simple and useful for “scheduling” payments, but whoever holds the keys can discard that transaction and create another one without the lock.
CheckLockTimeVerify (CLTV): a script operation that writes the restriction directly into the UTXO. In this case, the money “inherits” the lock: no spending is possible before the defined height/time, even if all the key holders want to change it.

There is also the CheckSequenceVerify (CSV) variant, which works similarly but is based on a relative interval of confirmations (e.g., “can be spent 144 blocks after this UTXO is confirmed”).

These features make it possible to create contracts such as vaults with a recovery period, inheritances with future unlocking, or scheduled payments that only become valid after a certain date.

a) nLockTime in practice Goal: create a transaction that can only be mined after a target block.

Choose the target block (e.g., current height + 2):

bitcoin-cli -datadir="." getblockcount
# 271141

The getblockcount command returns the current blockchain height. We can choose, for example, that the transaction can only be included from block 271145.

Create the transaction:

bitcoin-cli -datadir="." -rpcwallet="demo-signet" createrawtransaction "[]" "{\"tb1q4asvsg6hhv6vwxzq5uy05wf6zzusp8me5xmlzv\":0.0001}" 271145
0200000000011027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7929230400

Fund the transaction:

bitcoin-cli -datadir="." -rpcwallet=demo-signet fundrawtransaction "0200000000011027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7929230400"
{
  "hex": "0200000001e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c29230400",
  "fee": 0.00000141,
  "changepos": 1
}

Sign the transaction:

bitcoin-cli -datadir="." -rpcwallet="demo-signet" signrawtransactionwithwallet "0200000001e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c29230400"
{
  "hex": "02000000000101e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c0247304402205e358ba9097c1f7efe67093fae52c4664cf17648f75185ae47a95a875db8fccb0220691d79b3eb4dc54b3c095e167340f084057b1f803f0375460ecfdc4c4af2dfa1012102ce170948697b4e2d96f3c85be5841c99a5deb2318855f9f041f23db9af7f62e829230400",
  "complete": true
}

Send the transaction:

Notice that if we try to broadcast the transaction before the defined block height, we get an error:

bitcoin-cli -datadir="." getblockcount
271143

bitcoin-cli -datadir="." sendrawtransaction "02000000000101e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c0247304402205e358ba9097c1f7efe67093fae52c4664cf17648f75185ae47a95a875db8fccb0220691d79b3eb4dc54b3c095e167340f084057b1f803f0375460ecfdc4c4af2dfa1012102ce170948697b4e2d96f3c85be5841c99a5deb2318855f9f041f23db9af7f62e829230400"
error code: -26
error message:
non-final

In Bitcoin, the nLockTime field works only as a block validity rule, not as an automatic scheduler. It defines the lowest block height (or timestamp) at which the transaction can be included in the blockchain, but the network does not “hold” it until then. If you try to broadcast it before the limit is reached, nodes reject it with the non-final error and nothing stays pending. That is why the software or script that creates the transaction must track the current height (for example, via getblockcount) and only broadcast when current_height is greater than or equal to the nLockTime value. This differs from a script timelock (such as OP_CHECKLOCKTIMEVERIFY), which writes the restriction into the output and lets you send the funding transaction today, guaranteeing it can only be spent after the deadline, without depending on external monitoring. When we send it after the target, it works:

bitcoin-cli -datadir="." getblockcount
271145

bitcoin-cli -datadir="." sendrawtransaction "02000000000101e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c0247304402205e358ba9097c1f7efe67093fae52c4664cf17648f75185ae47a95a875db8fccb0220691d79b3eb4dc54b3c095e167340f084057b1f803f0375460ecfdc4c4af2dfa1012102ce170948697b4e2d96f3c85be5841c99a5deb2318855f9f041f23db9af7f62e829230400"
# 2c91cbd4e8bccacb42020eb88a1df0816d99fae7e2ee12ff6a8c996ca282374b

b) CLTV with Miniscript (a “strong” timelock on the UTXO)

Goal: create a P2WSH address whose script requires a minimum block height to spend.

Let’s go step by step.

Create a new wallet

We will create a new wallet so as not to mix it with other examples.

bitcoin-cli -datadir="." createwallet carteira_cltv
{
  "name": "carteira_cltv"
}

Create a new address and get its information

With the new wallet, we can generate a new address.

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" getnewaddress
# tb1q84ysz0zng7m8yad6zrps3uyn6reu977v85x0ga

Next, we can get the information for this new address (we will use it below):

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" getaddressinfo tb1q84ysz0zng7m8yad6zrps3uyn6reu977v85x0ga
{
  "address": "tb1q84ysz0zng7m8yad6zrps3uyn6reu977v85x0ga",
  "scriptPubKey": "00143d49013c5347b67275ba10c308f093d0f3c2fbcc",
  "ismine": true,
  "solvable": true,
  "desc": "wpkh([261430f9/84h/1h/0h/0/0]03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79)#l4tsyqsx",
  "parent_desc": "wpkh([261430f9/84h/1h/0h]tpubDDEKB1hKK8aCiLLPE35AqyEnRSbRTWgo27VVfG1iF8mdsJnYvuss736NutifM2NWnH78AVjW4hvHaDg3CzW7ZAHXVBMgPvoiYuYrZ5RgJii/0/*)#2hke87n4",
  "iswatchonly": false,
  "isscript": false,
  "iswitness": true,
  "witness_version": 0,
  "witness_program": "3d49013c5347b67275ba10c308f093d0f3c2fbcc",
  "pubkey": "03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79",
  "ischange": false,
  "timestamp": 1758845787,
  "hdkeypath": "m/84h/1h/0h/0/0",
  "hdseedid": "0000000000000000000000000000000000000000",
  "hdmasterfingerprint": "261430f9",
  "labels": [
    ""
  ]
}

From the pubkey, we can build a new, specific descriptor that produces addresses with a block-height restriction (after(271220)):

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" getdescriptorinfo "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))"
{
  "descriptor": "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry",
  "checksum": "gk4hzcry",
  "isrange": false,
  "issolvable": true,
  "hasprivatekeys": false
}

This command returns a descriptor already with its #CHECKSUM (in the example, #gk4hzcry).

Derive a new address from the descriptor

With the descriptor above, we can derive addresses that already carry the block-height restriction in their script.

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" deriveaddresses "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry"
[
  "tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave"
]

Any UTXO associated with the address tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave can only be spent from block 271220 onward.

We can check the current block:

bitcoin-cli -datadir="." getblockcount
271211

Send funds to the timelock address

We can send some funds to this newly created address so that we can then test whether we are able to make transactions before the defined block height. We can use a faucet or send BTC from another wallet, as in the example below:

bitcoin-cli -datadir="." -rpcwallet="demo-signet" sendtoaddress "tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave" 0.0001
# 8cc8b2a47bff4a4b146f16ca2656bfb341bb95040ace91b4d6698e3c34d00c3a

In fact, that is all there is to using a script timelock (CLTV); it is already in place. The next steps only serve to demonstrate that we will need to wait until the specific block height to be able to spend this UTXO.

Create a watch-only wallet

Remember that, when Bitcoin Core creates a wallet, it creates it with those 8 default descriptors. In the previous steps, we generated a new address for the carteira_cltv wallet from a new descriptor. However, by default Core does not automatically associate all UTXOs of this new descriptor with the wallet. Therefore, if we run listunspent on the carteira_cltv wallet, it will not show the UTXO from the transaction above (the one that funded the address). To fix this, we will create a new watch-only wallet:

bitcoin-cli -datadir="." createwallet carteira_cltv_wo true
{
  "name": "carteira_cltv_wo"
}

And right after, we will use the importdescriptors command so that this new wallet sees the UTXOs associated with the addresses generated by the new descriptor:

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo importdescriptors "[{\"desc\":\"wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry\",\"timestamp\":0,\"label\":\"cltv-271220\"}]"
[
  {
    "success": true
  }
]

This command may take a few minutes, since it scans all existing UTXOs.

Once the transaction that sent funds to this address is confirmed, we will be able to see the UTXO:

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo listunspent
[
  {
    "txid": "8cc8b2a47bff4a4b146f16ca2656bfb341bb95040ace91b4d6698e3c34d00c3a",
    "vout": 1,
    "address": "tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave",
    "label": "cltv-271220",
    "witnessScript": "2103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b1",
    "scriptPubKey": "002092d6f062c222e0e4293d550de1f35c9cf9fbad6d7c8c750bd249f216168eb01c",
    "amount": 0.00010000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wsh(and_v(v:pk([3d49013c]03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#dz9nuz04",
    "parent_descs": [
      "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry"
    ],
    "safe": true
  }
]

Create a transaction and try to send it

Now let’s create a PSBT transaction to try to spend the locked UTXO.

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo createpsbt "[{\"txid\":\"8cc8b2a47bff4a4b146f16ca2656bfb341bb95040ace91b4d6698e3c34d00c3a\",\"vout\":1,\"sequence\":4294967293}]" "[{\"tb1q3hhxstxlemumvsw2v8cgxwf860f6hxyk7p0d6v\":0.00009800}]" 271220
cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiMAQAAAAD9////AUgmAAAAAAAAFgAUje5oLN/O+bZBymHwgzkn09OrmJZ0IwQAAAAA

To be able to spend, I need to build a transaction in the expected format, so that the unlocking script is correct. Thus, we need to create the PSBT with the transaction’s TXID (with its vout), sequence, the destination address, the amount, and the unlock block height.

Each input of a transaction has a Sequence field.

If it stays at the maximum value (0xffffffff), the transaction’s nLockTime is ignored.
If you use a smaller value (e.g., 0xfffffffd), nLockTime takes effect.

In our case, the real timelock is in the UTXO’s script (OP_CHECKLOCKTIMEVERIFY generated by after(...)). nSequence only ensures that the transaction respects this timelock; it cannot “unlock” the UTXO early. Even if someone tries to change nSequence to get around it, the network will keep requiring that the minimum block height be reached before spending.

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo walletprocesspsbt "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiMAQAAAAD9////AUgmAAAAAAAAFgAUje5oLN/O+bZBymHwgzkn09OrmJZ0IwQAAAAA" false
{
  "psbt": "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiM...(shortened)...",
  "complete": false
}

We complete/sign the PSBT transaction with the watch-only wallet. And then with the original wallet (which has the private keys):

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv walletprocesspsbt "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiM...(shortened)..." true
{
  "psbt": "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiM...(shortened)...",
  "complete": true,
  "hex": "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400"
}

We finalize the PSBT:

bitcoin-cli -datadir="." finalizepsbt "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiM...(shortened)..."
{
  "hex": "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400",
  "complete": true
}

And we send it:

bitcoin-cli -datadir="." sendrawtransaction "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400"
error code: -26
error message:
non-final

Notice that it errors out. The non-final message indicates that this transaction cannot yet be accepted into the mempool.

We wait for the block height to pass 271220 and send it again:

bitcoin-cli -datadir="." getblockcount
271227

bitcoin-cli -datadir="." sendrawtransaction "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400"
e2b64a372d5bab18658f5ce14bc27cd6c502c7026b8bc5853462c254638603b1

Throughout this article, we saw how to move beyond the basic “send and sign” to build well-structured and more secure transactions in Bitcoin Core.

PSBT separates responsibilities (create, sign, finalize), enabling collaborative workflows and offline environments; multisig (m-of-n) adds resilience against key loss and compromise; and timelocks, both nLockTime (in the transaction) and CLTV/CSV (in the script, via Miniscript), let you enforce when a UTXO can be spent. Together, these features form complementary layers: key policy (multisig), time policy (timelocks), and a secure transport format (PSBT). The result is a sending process that is auditable, reproducible, and resistant to operational failures, ready to evolve from the signet lab to professional day-to-day practice.

Transferências Avançadas e Segurança no Bitcoin

2026-10-14T00:00:00+00:00

Transferências Avançadas e Segurança

Nos três artigos anteriores da série Transferências no Bitcoin, exploramos desde a anatomia básica de uma transação até estratégias mais eficientes de envio, sempre com ênfase prática no uso do Bitcoin Core em redes de teste. Agora, avançamos: além de movimentar bitcoins de forma correta e econômica, é hora de pensar em como fortalecer a segurança de cada transferência.

Esse passo é essencial porque, no ecossistema Bitcoin, a proteção não depende apenas de guardar bem a chave privada. O conceito de defesa em camadas mostra que a segurança verdadeira surge quando criamos várias barreiras: desde a geração das chaves até a própria forma como estruturamos as transações. Recursos como multisig e timelocks permitem criar operações que resistem a perdas, roubos ou acessos não autorizados, oferecendo resiliência mesmo em cenários de falha.

Neste artigo, vamos ver como aplicar cada uma dessas técnicas, combinando teoria e prática para que suas transferências não apenas aconteçam, mas sejam mais robustas e versáteis. Antes, vamos entender as PSBT (Partially Signed Bitcoin Transaction), que são fundamentais para utilização desses recursos avançados.

PSBT – Transações Parcialmente Assinadas

A PSBT é um padrão definido na BIP174 que permite criar, compartilhar e assinar transações de forma colaborativa.

Ela separa nitidamente as etapas:

Criação da transação bruta: quem seleciona UTXOs e define os destinos.
Assinatura: cada participante assina apenas sua parte, em seu próprio dispositivo.
Finalização/Broadcast: montagem final e envio à rede.

Isso garante que nenhum dispositivo precisa de todas as chaves nem de acesso total à internet, o que é essencial para multisig, hardware wallets ou setups air-gapped.

Comandos básicos no Bitcoin Core:

Etapa	Comando
Criar PSBT com inputs/outputs definidos	`walletcreatefundedpsbt`
Assinar parcialmente	`walletprocesspsbt`
Combinar várias PSBTs (vários signatários)	`combinepsbt`
Finalizar (gera hex transmitível)	`finalizepsbt`
Enviar	`sendrawtransaction`

PSBT é útil mesmo com 1 assinante quando você separa ambientes: cria a transação em uma máquina e assina em outra (segura/offline).

Vamos a um exemplo no Bitcoin Core.

0) Pré-requisitos

Você já tem uma carteira com saldo em signet.

1) Criar a PSBT (seleciona UTXOs e define saídas)

bitcoin-cli -datadir="." walletcreatefundedpsbt \
  '[]' '[{"tb1q2tygw0rd24cgrrj9dajqrh398clxucnhdwlxew":0.0001}]' \
  0 '{"subtractFeeFromOutputs":[0]}' true
{
  "psbt": "cHNidP8BAHECAAAAAXT7uaRFVyzfv8vbDqsOc4AWZzxAoX0SgXzlK63dkuV+AAAAAAD9////Ao4hAAAAAAAAFgAUUsiHPG1VcIGORW9kAd4lPj5uYnf+WQEAAAAAABYAFO7wQWnkgYcWv54ru1f5kZA+PWOTAAAAAAABAHECAAAAAS0mLffRUqI69eSsvc7Kr1Gcvn0FbSfYGqHxIdrYytV9AAAAAAD9////Ag6BAQAAAAAAFgAULfNI+6HV8XwNm6k215opak1NIUOEAwAAAAAAABYAFFWyh7v5Wliw/eMsyvIhdIjcFcOWAAAAAAEBHw6BAQAAAAAAFgAULfNI+6HV8XwNm6k215opak1NIUMiBgMtyDX9uzN8sBoE/EgnwKqA1165uji362cmhOoaNApSshh3Rt53VAAAgAEAAIAAAACAAQAAAAQAAAAAIgID3LDPfRo5Dnqny9PwT9gVhlm4NpBIJxhHkpOqHJuWGA8Yd0bed1QAAIABAACAAAAAgAAAAAAHAAAAACICAibyHkvhAx+N5YcfQp9R5xJa97neDE4nHzBDceWY5iIsGHdG3ndUAACAAQAAgAAAAIABAAAABQAAAAA=",
  "fee": 0.00001410,
  "changepos": 1
}

2) Assinar parcialmente (na mesma carteira)

bitcoin-cli -datadir="." walletprocesspsbt "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"
{
  "psbt": "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",
  "complete": true,
  "hex": "0200000000010174fbb9a445572cdfbfcbdb0eab0e738016673c40a17d12817ce52baddd92e57e0000000000fdffffff02fe590100000000001600143c1d4d4564dd832cd1a19165b082169f205751ee8e2100000000000016001452c8873c6d5570818e456f6401de253e3e6e62770247304402202bdc9363f168b9dc4257bcd0e40ac2b1c49b0c2260fddfa54a13aab28796890b022031cae8deeee571148017b3d0ace059552bf67933d8f67ff22647bc16a70c6f180121032dc835fdbb337cb01a04fc4827c0aa80d75eb9ba38b7eb672684ea1a340a52b200000000"
}

walletprocesspsbt adiciona as assinaturas que a carteira consegue fazer. Em uma carteira comum (não multisig), isso deixa complete=true.

Explicando os campos que o comando retorna:

psbt

É a transação parcialmente assinada (ainda em formato PSBT, base64).
Serve se você ainda fosse passar para outro signatário ou quisesse guardar o arquivo.
Caso complete fosse false, esse seria o valor a enviar para o próximo participante ou para usar em finalizepsbt.

complete

true significa que todas as assinaturas necessárias já foram adicionadas.
Se fosse false, você continuaria circulando o PSBT entre as partes ou rodaria combinepsbt etc.

hex

É a transação Bitcoin final já serializada (raw hex) pronta para a rede.
Quando complete é true, o Core já te entrega esse hex, que já pode ser transmitido.

3) Finalizar e transmitir

Como complete = true, **não precisa chamar finalizepsbt. Basta pegar o valor de hex e transmitir:

bitcoin-cli -datadir="." sendrawtransaction "0200000000010174fbb9a445572cdfbfcbdb0eab0e738016673c40a17d12817ce52baddd92e57e0000000000fdffffff02fe590100000000001600143c1d4d4564dd832cd1a19165b082169f205751ee8e2100000000000016001452c8873c6d5570818e456f6401de253e3e6e62770247304402202bdc9363f168b9dc4257bcd0e40ac2b1c49b0c2260fddfa54a13aab28796890b022031cae8deeee571148017b3d0ace059552bf67933d8f67ff22647bc16a70c6f180121032dc835fdbb337cb01a04fc4827c0aa80d75eb9ba38b7eb672684ea1a340a52b200000000"
# a1a93c02cfb449040677950d1abf33f57c923273d5f091c942c08d229e638ce4

Se complete = false, **usaríamos o "psbt" retornado:

bitcoin-cli -datadir="." finalizepsbt "<PSBT_ASSINADA>"

Esse comando geraria o hex final a ser transmitido.

Multisig

Multisig é um esquema de custódia no Bitcoin em que um gasto só é válido quando um número mínimo pré-definido de chaves entre várias participantes assina a transação, como “2-de-3” ou “3-de-5”, aumentando a segurança e permitindo controle compartilhado.

Vantagens:

Resistência a roubo/perda: 1 chave comprometida não gasta os fundos (em 2-de-3); perda de 1 chave ainda permite recuperação.
Herança/backup: distribuição de chaves entre pessoas/cofres diferentes.
Governança: políticas de aprovação (m-de-n) para empresas/DAOs.

Vamos ver um exemplo prático no Bitcoin Core:

1) Criar três carteiras (participantes)

bitcoin-cli -datadir="." createwallet carteira1 true true "" true true
bitcoin-cli -datadir="." createwallet carteira2 true true "" true true
bitcoin-cli -datadir="." createwallet carteira3 true true "" true true

Criamos carteiras com chaves privadas e com descriptors. Evite blank=true e disable_private_keys=true para não obter carteiras “vazias”.

2) Obter os xpubs (com fingerprint/derivação)

Para cada carteira, liste os descriptors públicos e copie as linhas de recebimento (…/0/)** e **troco (…/1/):

bitcoin-cli -datadir="." -rpcwallet=carteira1 listdescriptors
{
  "wallet_name": "carteira1",
  "descriptors": [
    ...,
    {
      "desc": "wpkh([ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/0/*)#jr2a4z9x",
      "timestamp": 1758650612,
      "active": true,
      "internal": false,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    },
    {
      "desc": "wpkh([ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/1/*)#rh0ugh47",
      "timestamp": 1758650613,
      "active": true,
      "internal": true,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    }
  ]
}

bitcoin-cli -datadir="." -rpcwallet=carteira2 listdescriptors
{
 ...,
    {
      "desc": "wpkh([1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/0/*)#k32vf2uu",
      "timestamp": 1758650639,
      "active": true,
      "internal": false,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    },
    {
      "desc": "wpkh([1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/1/*)#890d5lvy",
      "timestamp": 1758650640,
      "active": true,
      "internal": true,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    }
  ]
}

bitcoin-cli -datadir="." -rpcwallet=carteira3 listdescriptors
{
  "wallet_name": "carteira3",
  "descriptors": [
    ...,
    {
      "desc": "wpkh([fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/0/*)#5szljz27",
      "timestamp": 1758650645,
      "active": true,
      "internal": false,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    },
    {
      "desc": "wpkh([fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/1/*)#9y870h6x",
      "timestamp": 1758650645,
      "active": true,
      "internal": true,
      "range": [
        0,
        999
      ],
      "next": 0,
      "next_index": 0
    }
  ]
}

O que copiar: os descriptors públicos de recebimento (…/0/) e troco (…/1/), eles trazem fingerprint + caminho (ex.: [ba39c771/84h/1h/0h]tpub…/0/*), que é essencial para montar o multisig corretamente.

Padrão de endereço: os exemplos usam a derivação 84h/1h/0h (Bech32, P2WPKH para singlesig). No multisig, vamos combiná-los em P2WSH (wsh(sortedmulti(…))).

3) Criar carteira multisig (watch-only) e importar os descriptors multisig (recebimento e troco)

Por que “watch-only”? Essa carteira vê UTXOs, gera endereços e cria PSBTs, mas não tem chaves privadas, as assinaturas acontecem nas carteiras participantes (carteira1, 2 e 3).

bitcoin-cli -datadir="." createwallet multisig-2of3 true true "" true true
{
  "name": "multisig-2of3",
  "warnings": [
    "Empty string given as passphrase, wallet will not be encrypted."
  ]
}

bitcoin-cli -datadir="." -rpcwallet=multisig-2of3 importdescriptors [{\"desc\":\"wsh(sortedmulti(2,[ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/0/*,[1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/0/*,[fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/0/*))#ed8gy0hl\",\"active\":true,\"timestamp\":\"now\"},{\"desc\":\"wsh(sortedmulti(2,[ba39c771/84h/1h/0h]tpubDCYmREHcMiWLvGJ4goQeYcvNARJtp8Bcuf2wSo5NZKHLHiu91xoH1135ngN3MmHHB9L6bYabHiFkBamEavcVeEoKGDWj7op1atN6xeCotwk/1/*,[1b69360a/84h/1h/0h]tpubDD2gr2TXupxDBjtLUnFkWVsNMYNNcPeLrRmR4M9Eo7NEShdCnJRcsccxRtzAKDT1F2cXGdSKPTerBX2FsYRUcDZtRNzd7rPeS9Fg3HMBC4x/1/*,[fd4d4620/84h/1h/0h]tpubDDnWDjzpV82Wxdr7woANyPdKnSvQvEERPnzxoK2iPLUf8M8HA6Dr1rKw5FqnUFabN5zbQjexYNTCW8QC16NUpd6m1JogodyjLe5fRYvQ5KT/1/*))#tcmu8qku\",\"active\":true,\"internal\":true,\"timestamp\":\"now\"}]
[
  {
    "success": true,
    "warnings": [
      "Range not given, using default keypool range"
    ]
  },
  {
    "success": true,
    "warnings": [
      "Range not given, using default keypool range"
    ]
  }
]

sortedmulti: garante uma ordem determinística das chaves (independente da ordem de entrada), evitando endereços diferentes para o mesmo conjunto de chaves. O aviso “Range not given” apenas informa que o Core usará o range padrão 0–999 para geração dos endereços. Para a maioria dos casos, está ótimo.

4) Receber fundos na multisig

Gere um novo endereço para essa nova carteira multisig:

bitcoin-cli -datadir="." -rpcwallet=multisig-2of3 getnewaddress
# tb1qrlwt49k9hqgj7m3rlc4elfj3fxe96l93zz9ez5209z8uskrqg7yqhl3v88

Envie alguns sats para o endereço gerado (via faucet de signet). Aguarde 1+ confirmações.

5) Criar a PSBT de gasto (na multisig)

bitcoin-cli -datadir="." -rpcwallet=multisig-2of3 walletcreatefundedpsbt "[]" "[{\"tb1qqu7d6zmh5mpf07xd7t9aehe0re63hfqk2wh2ew6045zc5svshphq7j4eek\":0.00001}]" 0 "{\"subtractFeeFromOutputs\":[0]}" true
{
  "psbt": "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",
  "fee": 0.00000201,
  "changepos": 0
}

walletcreatefundedpsbt seleciona UTXOs, monta a transação, calcula a taxa e devolve uma

PSBT com os metadados para assinatura.

subtractFeeFromOutputs: se ligado para o índice 0, a taxa é “debitada” daquela saída (útil para enviar “o que sobrar” sem ficar ajustando manualmente).

6) Assinar em duas carteiras (Carteira1 e Carteira2, separadamente)

bitcoin-cli -datadir="." -rpcwallet=carteira1 walletprocesspsbt "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"
{
  "psbt": "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",
  "complete": false
}

bitcoin-cli -datadir="." -rpcwallet=carteira2 walletprocesspsbt "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"
{
  "psbt": "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",
  "complete": false
}

Cada participante assina com walletprocesspsbt.

Sequencial vs. paralelo:

Sequencial: saída da carteira1 (psbt já com 1 assinatura) entra na carteira2 → geralmente já volta complete: true.
Paralelo (a que usamos nesse exemplo): cada um assina a mesma PSBT original e depois você combina (próximo passo).

7) Combine os 2 PSBT assinados

bitcoin-cli -datadir="." combinepsbt "[\"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\",\"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\"]"
# cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZOWlsWzDBGdb6AQAAAAD9////AigjAAAAAAAAIgAgffrg1wuWTLU//NFkDdFKcLTiMQqIGXRBJYuZFOVjxmMfAwAAAAAAACIAIAc83Qt3psKX+M3yy9zfLx51G6QWU66su0+tBYpBkLhuAAAAAAABAIkCAAAAAVAByKT0ARhfFgU643lMMBY/UOnTo7PBxfKqTH7IFf1ZAAAAAAD9////An0DOwAAAAAAIlEgEOILQOfM8jum+vwMWifdS7i6Aexaov0TSmGb2+hRcQsQJwAAAAAAACIAIB/cupbFuBEvbiP+K5+mUUmyXXyxEIuRUU8oj8hYYEeIQiIEAAEBKxAnAAAAAAAAIgAgH9y6lsW4ES9uI/4rn6ZRSbJdfLEQi5FRTyiPyFhgR4giAgP4dZmjt6qXwHEd4+vJjHb3iWOOvinDaMxCHV/Mcrat+0cwRAIgC/OAYLP2UKZwKDp7ig54A070T7BuMmtmosw2Er4L3JMCIHc9wACs5v3Ap8iDl9t9YXJjYfsOceBXXH6ur+Ug/mONASICA14XUBIE5U5Gno30NXRTE2RHDeeqagGxynu4a2TkI34BRzBEAiAHqYF91QXzqirmLZSieTL/PraizIOBWHkKjeZfPdGj5gIgVby248StaxJCIj5PnKE8f+8NSaD6l04HSGXIFJKPqNUBAQVpUiECWYwaWJz6eoHcmtW76T5F8BK0ONuF+xIqo9ubqc6iHkYhA14XUBIE5U5Gno30NXRTE2RHDeeqagGxynu4a2TkI34BIQP4dZmjt6qXwHEd4+vJjHb3iWOOvinDaMxCHV/Mcrat+1OuIgYCWYwaWJz6eoHcmtW76T5F8BK0ONuF+xIqo9ubqc6iHkYY/U1GIFQAAIABAACAAAAAgAAAAAABAAAAIgYDXhdQEgTlTkaejfQ1dFMTZEcN56pqAbHKe7hrZOQjfgEYujnHcVQAAIABAACAAAAAgAAAAAABAAAAIgYD+HWZo7eql8BxHePryYx294ljjr4pw2jMQh1fzHK2rfsYG2k2ClQAAIABAACAAAAAgAAAAAABAAAAAAEBaVIhAo2L2uqYKn9XfAw1aDeOhKEbmlP6sv8HkYjjbVUQI7jvIQLH5myrB7F+lw/ySrUsgg31aaqAStuBl9Cq7GJbmtKlJyED6X5J7MLr9uYyv0+NeYks9h1ES9DOQDuOfx1TfN/A5xRTriICAo2L2uqYKn9XfAw1aDeOhKEbmlP6sv8HkYjjbVUQI7jvGLo5x3FUAACAAQAAgAAAAIABAAAAAAAAACICAsfmbKsHsX6XD/JKtSyCDfVpqoBK24GX0KrsYlua0qUnGP1NRiBUAACAAQAAgAAAAIABAAAAAAAAACICA+l+SezC6/bmMr9PjXmJLPYdREvQzkA7jn8dU3zfwOcUGBtpNgpUAACAAQAAgAAAAIABAAAAAAAAAAABAWlSIQJkiZ30QhjhldcZUe2N87U/cFnPK8JN9Rj4k0RLXq+biyEC2/LkBDTwmj9TwSW/t+1aDP4fUAv6y+RxE3l2dW4RVOohA9mgIUrpO50byq0KR8I+D6N9AEUT0z4nVY2olSI48CaxU64iAgJkiZ30QhjhldcZUe2N87U/cFnPK8JN9Rj4k0RLXq+bixi6OcdxVAAAgAEAAIAAAACAAAAAAAIAAAAiAgLb8uQENPCaP1PBJb+37VoM/h9QC/rL5HETeXZ1bhFU6hgbaTYKVAAAgAEAAIAAAACAAAAAAAIAAAAiAgPZoCFK6TudG8qtCkfCPg+jfQBFE9M+J1WNqJUiOPAmsRj9TUYgVAAAgAEAAIAAAACAAAAAAAIAAAAA

Quando usar: se os signatários assinaram em paralelo (cada um pegou a PSBT original).

Resultado esperado: a PSBT combinada já deve conter as 2 assinaturas exigidas (2-de-3).

8) Finalizar e transmitir

bitcoin-cli -datadir="." finalizepsbt "cHNidP8BAIkCAAAAAbALDAmCzaLpmGLM3HosXOuodp03BnzZOWlsWzDBGdb6AQAAAAD9////AigjAAAAAAAAIgAgffrg1wuWTLU//NFkDdFKcLTiMQqIGXRBJYuZFOVjxmMfAwAAAAAAACIAIAc83Qt3psKX+M3yy9zfLx51G6QWU66su0+tBYpBkLhuAAAAAAABAIkCAAAAAVAByKT0ARhfFgU643lMMBY/UOnTo7PBxfKqTH7IFf1ZAAAAAAD9////An0DOwAAAAAAIlEgEOILQOfM8jum+vwMWifdS7i6Aexaov0TSmGb2+hRcQsQJwAAAAAAACIAIB/cupbFuBEvbiP+K5+mUUmyXXyxEIuRUU8oj8hYYEeIQiIEAAEBKxAnAAAAAAAAIgAgH9y6lsW4ES9uI/4rn6ZRSbJdfLEQi5FRTyiPyFhgR4giAgP4dZmjt6qXwHEd4+vJjHb3iWOOvinDaMxCHV/Mcrat+0cwRAIgC/OAYLP2UKZwKDp7ig54A070T7BuMmtmosw2Er4L3JMCIHc9wACs5v3Ap8iDl9t9YXJjYfsOceBXXH6ur+Ug/mONASICA14XUBIE5U5Gno30NXRTE2RHDeeqagGxynu4a2TkI34BRzBEAiAHqYF91QXzqirmLZSieTL/PraizIOBWHkKjeZfPdGj5gIgVby248StaxJCIj5PnKE8f+8NSaD6l04HSGXIFJKPqNUBAQVpUiECWYwaWJz6eoHcmtW76T5F8BK0ONuF+xIqo9ubqc6iHkYhA14XUBIE5U5Gno30NXRTE2RHDeeqagGxynu4a2TkI34BIQP4dZmjt6qXwHEd4+vJjHb3iWOOvinDaMxCHV/Mcrat+1OuIgYCWYwaWJz6eoHcmtW76T5F8BK0ONuF+xIqo9ubqc6iHkYY/U1GIFQAAIABAACAAAAAgAAAAAABAAAAIgYDXhdQEgTlTkaejfQ1dFMTZEcN56pqAbHKe7hrZOQjfgEYujnHcVQAAIABAACAAAAAgAAAAAABAAAAIgYD+HWZo7eql8BxHePryYx294ljjr4pw2jMQh1fzHK2rfsYG2k2ClQAAIABAACAAAAAgAAAAAABAAAAAAEBaVIhAo2L2uqYKn9XfAw1aDeOhKEbmlP6sv8HkYjjbVUQI7jvIQLH5myrB7F+lw/ySrUsgg31aaqAStuBl9Cq7GJbmtKlJyED6X5J7MLr9uYyv0+NeYks9h1ES9DOQDuOfx1TfN/A5xRTriICAo2L2uqYKn9XfAw1aDeOhKEbmlP6sv8HkYjjbVUQI7jvGLo5x3FUAACAAQAAgAAAAIABAAAAAAAAACICAsfmbKsHsX6XD/JKtSyCDfVpqoBK24GX0KrsYlua0qUnGP1NRiBUAACAAQAAgAAAAIABAAAAAAAAACICA+l+SezC6/bmMr9PjXmJLPYdREvQzkA7jn8dU3zfwOcUGBtpNgpUAACAAQAAgAAAAIABAAAAAAAAAAABAWlSIQJkiZ30QhjhldcZUe2N87U/cFnPK8JN9Rj4k0RLXq+biyEC2/LkBDTwmj9TwSW/t+1aDP4fUAv6y+RxE3l2dW4RVOohA9mgIUrpO50byq0KR8I+D6N9AEUT0z4nVY2olSI48CaxU64iAgJkiZ30QhjhldcZUe2N87U/cFnPK8JN9Rj4k0RLXq+bixi6OcdxVAAAgAEAAIAAAACAAAAAAAIAAAAiAgLb8uQENPCaP1PBJb+37VoM/h9QC/rL5HETeXZ1bhFU6hgbaTYKVAAAgAEAAIAAAACAAAAAAAIAAAAiAgPZoCFK6TudG8qtCkfCPg+jfQBFE9M+J1WNqJUiOPAmsRj9TUYgVAAAgAEAAIAAAACAAAAAAAIAAAAA"
{
  "hex": "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",
  "complete": true
}

finalizepsbt: valida o script, monta os witness e devolve o hex pronto para broadcast.

Por fim, o comando sendrawtransaction publica a transação na rede.

bitcoin-cli -datadir="." sendrawtransaction "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"
# af5f0813b622d6a21389af6cecbe9d5098d71cdee814e7ba70fcbe0a7d1ce407

Perceba, pela mempool, que é uma transação multisig 2 de 3:

Timelocks

No Bitcoin, timelock é o nome genérico para mecanismos que determinam quando uma transação ou um determinado UTXO pode ser gasto. Em vez de apenas exigir uma assinatura válida, o protocolo também verifica tempo ou altura de bloco, criando condições de “espera obrigatória”.

Existem duas formas principais.

nLockTime: um campo dentro da própria transação que define o bloco mínimo (ou um timestamp) a partir do qual a rede aceita incluí-la em um bloco. É simples e útil para “agendar” pagamentos, mas quem possui as chaves pode descartar essa transação e criar outra sem o bloqueio.
CheckLockTimeVerify (CLTV): uma operação de script que grava a restrição diretamente no UTXO. Nesse caso, o dinheiro “herda” a trava: nenhum gasto é possível antes da altura/tempo definido, mesmo que todos os donos das chaves queiram mudar.

Há ainda a variação CheckSequenceVerify (CSV), que funciona de forma parecida, mas com base em um intervalo relativo de confirmações (ex.: “pode gastar 144 blocos depois que este UTXO for confirmado”).

Esses recursos permitem criar contratos como cofres com período de resgate, heranças com desbloqueio futuro, ou pagamentos programados que só se tornam válidos depois de certa data.

a) nLockTime na prática Objetivo: criar uma transação que só pode ser minerada após um bloco-alvo.

Escolha o bloco-alvo (ex.: altura atual + 2):

bitcoin-cli -datadir="." getblockcount
# 271141

O comando getblockcount retorna a altura atual da blockchain. Podemos escolher, por exemplo, que a transação só poderá ser incluída a partir do bloco 271145.

Crie a transação:

bitcoin-cli -datadir="." -rpcwallet="demo-signet" createrawtransaction "[]" "{\"tb1q4asvsg6hhv6vwxzq5uy05wf6zzusp8me5xmlzv\":0.0001}" 271145
0200000000011027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7929230400

Complete a transação:

bitcoin-cli -datadir="." -rpcwallet=demo-signet fundrawtransaction "0200000000011027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7929230400"
{
  "hex": "0200000001e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c29230400",
  "fee": 0.00000141,
  "changepos": 1
}

Assine a transação:

bitcoin-cli -datadir="." -rpcwallet="demo-signet" signrawtransactionwithwallet "0200000001e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c29230400"
{
  "hex": "02000000000101e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c0247304402205e358ba9097c1f7efe67093fae52c4664cf17648f75185ae47a95a875db8fccb0220691d79b3eb4dc54b3c095e167340f084057b1f803f0375460ecfdc4c4af2dfa1012102ce170948697b4e2d96f3c85be5841c99a5deb2318855f9f041f23db9af7f62e829230400",
  "complete": true
}

Envie a transação:

Perceba que se tentarmos transmitir a transação antes da altura de bloco definida, obtemos um erro:

bitcoin-cli -datadir="." getblockcount
271143

bitcoin-cli -datadir="." sendrawtransaction "02000000000101e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c0247304402205e358ba9097c1f7efe67093fae52c4664cf17648f75185ae47a95a875db8fccb0220691d79b3eb4dc54b3c095e167340f084057b1f803f0375460ecfdc4c4af2dfa1012102ce170948697b4e2d96f3c85be5841c99a5deb2318855f9f041f23db9af7f62e829230400"
error code: -26
error message:
non-final

No Bitcoin, o campo nLockTime funciona apenas como uma regra de validade de bloco, não como um agendamento automático. Ele define a menor altura de bloco (ou timestamp) em que a transação pode ser incluída na blockchain, mas a rede não a “guarda” até lá. Se você tentar transmiti-la antes de o limite ser atingido, os nós rejeitam com o erro non-final e nada fica pendente. Por isso, o software ou script que cria a transação precisa acompanhar a altura atual (por exemplo, via getblockcount) e só transmitir quando current_height for maior ou igual ao valor de nLockTime. É diferente de um timelock em script (como OP_CHECKLOCKTIMEVERIFY), que grava a restrição na saída e permite enviar a transação de funding hoje, garantindo que ela só possa ser gasta após o prazo, sem depender de monitoramento externo. Ao enviarmos após o alvo, conseguimos:

bitcoin-cli -datadir="." getblockcount
271145

bitcoin-cli -datadir="." sendrawtransaction "02000000000101e48c639e228dc042c991f0d57332927cf533bf1a0d9577060449b4cf023ca9a10000000000fdffffff021027000000000000160014af60c82357bb34c71840a708fa393a10b9009f7961320100000000001600143c7fa3189d4e5c9e6ca96eba73a525c94bf8ff9c0247304402205e358ba9097c1f7efe67093fae52c4664cf17648f75185ae47a95a875db8fccb0220691d79b3eb4dc54b3c095e167340f084057b1f803f0375460ecfdc4c4af2dfa1012102ce170948697b4e2d96f3c85be5841c99a5deb2318855f9f041f23db9af7f62e829230400"
# 2c91cbd4e8bccacb42020eb88a1df0816d99fae7e2ee12ff6a8c996ca282374b

b) CLTV com Miniscript (timelock “forte” no UTXO)

Objetivo: criar um endereço P2WSH cujo script exige altura mínima de bloco para gastar.

Vamos ver um passo a passo.

Criar uma nova carteira

Vamos criar uma nova carteira para não misturar com outros exemplo.

bitcoin-cli -datadir="." createwallet carteira_cltv
{
  "name": "carteira_cltv"
}

Criar um novo endereço e obter informações

Como a nova carteira, podemos gerar um novo endereço.

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" getnewaddress
# tb1q84ysz0zng7m8yad6zrps3uyn6reu977v85x0ga

Em seguida podemos obter as informações desse novo endereço (utilizaremos a seguir):

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" getaddressinfo tb1q84ysz0zng7m8yad6zrps3uyn6reu977v85x0ga
{
  "address": "tb1q84ysz0zng7m8yad6zrps3uyn6reu977v85x0ga",
  "scriptPubKey": "00143d49013c5347b67275ba10c308f093d0f3c2fbcc",
  "ismine": true,
  "solvable": true,
  "desc": "wpkh([261430f9/84h/1h/0h/0/0]03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79)#l4tsyqsx",
  "parent_desc": "wpkh([261430f9/84h/1h/0h]tpubDDEKB1hKK8aCiLLPE35AqyEnRSbRTWgo27VVfG1iF8mdsJnYvuss736NutifM2NWnH78AVjW4hvHaDg3CzW7ZAHXVBMgPvoiYuYrZ5RgJii/0/*)#2hke87n4",
  "iswatchonly": false,
  "isscript": false,
  "iswitness": true,
  "witness_version": 0,
  "witness_program": "3d49013c5347b67275ba10c308f093d0f3c2fbcc",
  "pubkey": "03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79",
  "ischange": false,
  "timestamp": 1758845787,
  "hdkeypath": "m/84h/1h/0h/0/0",
  "hdseedid": "0000000000000000000000000000000000000000",
  "hdmasterfingerprint": "261430f9",
  "labels": [
    ""
  ]
}

A partir da pubkey, podemos obter as informações para um novo descritor específico que produza endereços com restrição de altura do bloco (after(271220)):

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" getdescriptorinfo "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))"
{
  "descriptor": "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry",
  "checksum": "gk4hzcry",
  "isrange": false,
  "issolvable": true,
  "hasprivatekeys": false
}

Esse comando irá retornar um descritor já com seu #CHECKSUM (no exemplo, #gk4hzcry).

Derivar um novo endereço a partir do descritor

Com o descritor acima, podemos derivar endereços que já tenham em seu script a restrição da altura do bloco.

bitcoin-cli -datadir="." -rpcwallet="carteira_cltv" deriveaddresses "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry"
[
  "tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave"
]

Qualquer UTXO associada ao endereço tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave só poderá ser gasta a partir do bloco 271220.

Podemos ver qual o bloco atual:

bitcoin-cli -datadir="." getblockcount
271211

Enviar saldo para o endereço timelock

Podemos enviar algum saldo para este endereço criado para que possamos testar em seguida se conseguiremos fazer transações antes da altura de bloco definida. Podemos usar um faucet ou mandar BTCs de outra carteira, como no exemplo abaixo:

bitcoin-cli -datadir="." -rpcwallet="demo-signet" sendtoaddress "tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave" 0.0001
# 8cc8b2a47bff4a4b146f16ca2656bfb341bb95040ace91b4d6698e3c34d00c3a

De fato, usar timelock por script (CLTV) é isso, já está pronto. Os próximos passos servirão apenas para demonstrar que precisaremos esperar até a altura do bloco específica para poder gastar esse UTXO.

Criar uma carteira Watch Only

Lembre-se que, quando o Bitcoin Core cria uma carteira, ele cria com aqueles 8 descritores padrões. Nas etapas anteriores, geramos um novo endereço pra carteira carteira_cltv a partir de um novo descritor. No entanto, o Core não tem por padrão associar todos UTXO desse novo descritor à carteira automaticamente. Logo, se usarmos um listunspent na carteira carteira_cltv, ele não irá mostrar o UTXO da transação acima (a que colocou saldo ao endereço). Para isso, criaremos uma nova carteira Watch Only:

bitcoin-cli -datadir="." createwallet carteira_cltv_wo true
{
  "name": "carteira_cltv_wo"
}

E logo a seguir, usaremos o comando importdescriptors para que essa nova carteira enxergue os UTXO associados aos endereços gerados pelo novo descritor:

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo importdescriptors "[{\"desc\":\"wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry\",\"timestamp\":0,\"label\":\"cltv-271220\"}]"
[
  {
    "success": true
  }
]

Esse comando pode demorar uns minutinhos, pois ele faz uma varredura em todos UTXOs existentes.

Assim que a transação que enviou saldo para esse endereço for confirmada, poderemos ver o UTXO:

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo listunspent
[
  {
    "txid": "8cc8b2a47bff4a4b146f16ca2656bfb341bb95040ace91b4d6698e3c34d00c3a",
    "vout": 1,
    "address": "tb1qjtt0qckzytswg2fa25x7ru6unnulhttd0jx82z7jf8epv95wkqwqcq3ave",
    "label": "cltv-271220",
    "witnessScript": "2103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b1",
    "scriptPubKey": "002092d6f062c222e0e4293d550de1f35c9cf9fbad6d7c8c750bd249f216168eb01c",
    "amount": 0.00010000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wsh(and_v(v:pk([3d49013c]03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#dz9nuz04",
    "parent_descs": [
      "wsh(and_v(v:pk(03a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79),after(271220)))#gk4hzcry"
    ],
    "safe": true
  }
]

Criar uma transação e tentar enviar

Agora vamos criar uma transação PSBT para tentar gastar a UTXO travada.

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo createpsbt "[{\"txid\":\"8cc8b2a47bff4a4b146f16ca2656bfb341bb95040ace91b4d6698e3c34d00c3a\",\"vout\":1,\"sequence\":4294967293}]" "[{\"tb1q3hhxstxlemumvsw2v8cgxwf860f6hxyk7p0d6v\":0.00009800}]" 271220
cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiMAQAAAAD9////AUgmAAAAAAAAFgAUje5oLN/O+bZBymHwgzkn09OrmJZ0IwQAAAAA

Para poder gastar, eu preciso montar uma transação com o formato esperado, de forma que o script de liberação seja o correto. Assim, precisamos criar a PSBT com o TXID da transação (com seu vout), sequence, o endereço de destino, o valor e a altura do bloco de liberação.

Cada input de uma transação tem um campo Sequence.

Se ele ficar no valor máximo (0xffffffff), o nLockTime da transação é ignorado.
Se você usa um valor menor (ex.: 0xfffffffd), o nLockTime passa a valer.

No nosso caso o timelock verdadeiro está no script do UTXO (OP_CHECKLOCKTIMEVERIFY gerado pelo after(...)). O nSequence só garante que a transação respeite esse timelock; ele não consegue “destravar” o UTXO antes. Mesmo que alguém tente mudar nSequence para burlar, a rede continuará exigindo que a altura mínima do bloco seja atingida para gastar.

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv_wo walletprocesspsbt "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiMAQAAAAD9////AUgmAAAAAAAAFgAUje5oLN/O+bZBymHwgzkn09OrmJZ0IwQAAAAA" false
{
  "psbt": "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiMAQAAAAD9////AUgmAAAAAAAAFgAUje5oLN/O+bZBymHwgzkn09OrmJZ0IwQAAAEAiQIAAAABLSYt99FSojr15Ky9zsqvUZy+fQVtJ9gaofEh2tjK1X0BAAAAAP3///8Cq/QFAAAAAAAiUSBBvNiOQzRikrFtQZ+SOr2H//vtnfnW1k0VJIOSi2uCvBAnAAAAAAAAIgAgktbwYsIi4OQpPVUN4fNcnPn7rW18jHUL0knyFhaOsBxoIwQAAQErECcAAAAAAAAiACCS1vBiwiLg5Ck9VQ3h81yc+futbXyMdQvSSfIWFo6wHAEFKCEDpj/gRUOo4soBlLqBGuB26zUMBwj14Ikl2wIKWbu+z3mtA3QjBLEiBgOmP+BFQ6jiygGUuoEa4HbrNQwHCPXgiSXbAgpZu77PeQQ9SQE8AAA=",
  "complete": false
}

Completamos/assinamos a transação PSBT com a carteira Watch Only. E depois com a carteira original (que tem as chaves privadas):

bitcoin-cli -datadir="." -rpcwallet=carteira_cltv walletprocesspsbt "cHNidP8BAFICAAAAAToM0DQ8jmnWtJHOCgSVu0Gzv1YmyhZvFEtK/3ukssiMAQAAAAD9////AUgmAAAAAAAAFgAUje5oLN/O+bZBymHwgzkn09OrmJZ0IwQAAAEAiQIAAAABLSYt99FSojr15Ky9zsqvUZy+fQVtJ9gaofEh2tjK1X0BAAAAAP3///8Cq/QFAAAAAAAiUSBBvNiOQzRikrFtQZ+SOr2H//vtnfnW1k0VJIOSi2uCvBAnAAAAAAAAIgAgktbwYsIi4OQpPVUN4fNcnPn7rW18jHUL0knyFhaOsBxoIwQAAQErECcAAAAAAAAiACCS1vBiwiLg5Ck9VQ3h81yc+futbXyMdQvSSfIWFo6wHAEFKCEDpj/gRUOo4soBlLqBGuB26zUMBwj14Ikl2wIKWbu+z3mtA3QjBLEiBgOmP+BFQ6jiygGUuoEa4HbrNQwHCPXgiSXbAgpZu77PeQQ9SQE8AAA=" true
{
  "psbt": "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",
  "complete": true,
  "hex": "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400"
}

Finalizamos a PSBT:

bitcoin-cli -datadir="." finalizepsbt "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"
{
  "hex": "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400",
  "complete": true
}

E a enviamos:

bitcoin-cli -datadir="." sendrawtransaction "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400"
error code: -26
error message:
non-final

Perceba que dá erro. A mensagem non-final indica que essa transação ainda não pode ser aceita na mempool.

Esperamos a altura do bloco passar de 271220 e enviamos novamente:

bitcoin-cli -datadir="." getblockcount
271227

bitcoin-cli -datadir="." sendrawtransaction "020000000001013a0cd0343c8e69d6b491ce0a0495bb41b3bf5626ca166f144b4aff7ba4b2c88c0100000000fdffffff0148260000000000001600148dee682cdfcef9b641ca61f0833927d3d3ab9896024730440220708bf414673d06837024b38300527ed89243504e98fb4645b76beb8c9f8d6298022010185c548463c3fabf475dc758e620dc46b83d6fe28fe6c34b80cf10f3dd72fb01282103a63fe04543a8e2ca0194ba811ae076eb350c0708f5e08925db020a59bbbecf79ad03742304b174230400"
e2b64a372d5bab18658f5ce14bc27cd6c502c7026b8bc5853462c254638603b1

Ao longo deste artigo, vimos como sair do “envia e assina” básico para montar transações bem estruturadas e mais seguras no Bitcoin Core.

A PSBT separa funções (criar, assinar, finalizar), permitindo fluxos colaborativos e ambientes offline; o multisig (m-de-n) adiciona resiliência contra perda e comprometimento de chaves; e os timelocks, tanto o nLockTime (na transação) quanto o CLTV/CSV (no script, via Miniscript), permitem impor quando um UTXO pode ser gasto. Juntos, esses recursos formam camadas complementares: política de chaves (multisig), política de tempo (timelocks) e um formato de transporte seguro (PSBT). O resultado é um processo de envio auditável, reproduzível e resistente a falhas operacionais, pronto para evoluir do laboratório em signet para práticas profissionais no dia a dia. **

Building Transactions in Bitcoin Core

2026-10-12T00:00:00+00:00

Building Transactions in Bitcoin Core

by Rafael Santos

In the previous article, we explored the anatomy of a Bitcoin transaction, understanding how inputs and outputs connect to the UTXO model and how Bitcoin Core can handle different levels of automation, from fully automatic creation to assembling raw transaction hex. That foundation was essential for understanding the protocol’s internal logic and seeing how each component of a transaction plays a vital role in network validation.

Now, we take things a step further: the goal of this article is to learn how to create transactions across different types and scenarios, putting manual transaction construction with Bitcoin Core into practice. We will start with simple examples and explore real-world situations, such as sending to multiple recipients (batching), creating transactions with change, consolidating UTXOs, and manually controlling fees.

To master transaction creation in Bitcoin Core, it is important to go beyond the simplest case and experiment with different scenarios that reflect real-world usage. Each of these scenarios teaches us something specific about how the protocol works and how we can achieve greater control over our UTXOs and fees.

In this article, we will use the regtest network—do not forget to configure your bitcoin.conf file. You can also use signet, though you will need to wait for sBTC to arrive after requesting from a faucet.

Simple Transactions and the Role of Change

This is the most basic example: spending a single UTXO to send funds to a single recipient. Yet even in a “simple transaction,” there are critical nuances to consider. If you do not have any UTXOs, create an address for your wallet and mine 101 blocks (to make coinbase rewards spendable):

bitcoin-cli -datadir="." getnewaddress
# bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p

bitcoin-cli -datadir="." generatetoaddress 101 bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p

First, let’s list the available UTXOs in the wallet:

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "c3fef1a9764c57262ef70c2f11eb5bf548cbbcaeb7d900a77ae9ac25cb3954de",
    "vout": 0,
    "address": "bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p",
    "label": "",
    "scriptPubKey": "0014f4d71c42d89f7c185c7c2d56a86968484c026ff6",
    "amount": 50.00000000,
    "confirmations": 101,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/0]024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba7)#ah5fng3d",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  }
]

In this case, we have a UTXO with 50 BTC to spend. Let’s look at a few scenarios.

1. Sending partial funds, letting Core handle change

Suppose we want to send 0.5 BTC and let Core calculate the fee and generate a change address.

a. Create the raw hex without fee or change

bitcoin-cli -datadir="." createrawtransaction   '[{"txid":"c3fef1a9764c57262ef70c2f11eb5bf548cbbcaeb7d900a77ae9ac25cb3954de","vout":0}]'   '{"bcrt1qkqp9xzkre29gl7kl7d3s264nstysw7fqjj5pqf":0.5}'
0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0180f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c907792000000000

b. Fund with automatic fee and change

The hex generated above is passed to the fundrawtransaction command, which completes the transaction by adding a fee and a change output.

bitcoin-cli -datadir="." fundrawtransaction "0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0180f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c907792000000000"  '{"feeRate":0.00001000}'
{
  "hex": "0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a472700000000",
  "fee": 0.00000141,
  "changepos": 1
}

A new hex string is generated, now representing the complete funded transaction.

c. Sign and send

bitcoin-cli -datadir="." signrawtransactionwithwallet "0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a472700000000"
{
  "hex": "02000000000101de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a4727024730440220139015403f1787b993f84616a737c4a51ac93976cae845e1bc3949a8245a21c702200fa867025026dd8a624896265bf9c44130d87c49845a4251f3917e79a042f87b0121024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba700000000",
  "complete": true
}

signrawtransactionwithwallet signs the transaction, and sendrawtransaction broadcasts it to the network.

bitcoin-cli -datadir="." sendrawtransaction "02000000000101de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a4727024730440220139015403f1787b993f84616a737c4a51ac93976cae845e1bc3949a8245a21c702200fa867025026dd8a624896265bf9c44130d87c49845a4251f3917e79a042f87b0121024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba700000000"
1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e

Next, we mine one more block to confirm the broadcast transaction.

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

Then we can inspect our UTXOs once again.

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "b260fe7dd4eac4dca8b70d58e8cff68fb3f5753a61dc0856e658bbe731736c90",
    "vout": 0,
    "address": "bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p",
    "label": "",
    "scriptPubKey": "0014f4d71c42d89f7c185c7c2d56a86968484c026ff6",
    "amount": 50.00000000,
    "confirmations": 101,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/0]024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba7)#ah5fng3d",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e",
    "vout": 0,
    "address": "bcrt1qkqp9xzkre29gl7kl7d3s264nstysw7fqjj5pqf",
    "label": "",
    "scriptPubKey": "0014b002530ac3ca8a8ffadff363056ab382c9077920",
    "amount": 0.50000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/1]0238caef26a2025d89d4230bcc7e2d1dbdcc8ce51ce1c07cd4509a76495bba07d9)#8q3llhqf",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e",
    "vout": 1,
    "address": "bcrt1qln0za67dgh2ws55s0kx7wpg7t20f53e8envezx",
    "scriptPubKey": "0014fcde2eebcd45d4e852907d8de7051e5a9e9a4727",
    "amount": 49.49999859,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/1/0]03f032737bcfe1ccb7cf642458916102c22386727a2e3be2f36cdc4cb6ab37c3b9)#nyyqzwmx",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/1/*)#jtyys78l"
    ],
    "safe": true
  }
]

Notice that we now have 3 UTXOs. The first corresponds to the block reward from the mining step we just performed, so we can ignore it here. The second UTXO belongs to the address we sent the transaction to. The third is the change address generated by the transaction, containing 49.49999859 BTC (the original 50 BTC minus 0.5 BTC sent minus the mining fee).

2. Spending the entire amount, subtracting the fee automatically

In this scenario, we want to send the entire UTXO balance to a single address without generating a change address.

Bitcoin Core allows the transaction fee to be deducted directly from the send amount, so that the final output already accounts for the mining fee.

a. Create destination address

bitcoin-cli -datadir="." getnewaddress
# bcrt1qkyrgk8wkau455lytvggyp5wwtds2rr2m0f5kfg

b. Send full balance, subtracting the fee We can use the sendtoaddress command with the subtractfeefromamount=true parameter to sweep the entire balance of a UTXO:

bitcoin-cli -datadir="." sendtoaddress \
  bcrt1qkyrgk8wkau455lytvggyp5wwtds2rr2m0f5kfg \
  49.49999859 \
  "" "" \
  true
# 828ec7cedc36f9517bd44a8e2a813be906698125c7c80b9a71a3202f2c09438c

The amount of 49.49999859 BTC corresponds to the change UTXO we received in the previous scenario.
The final argument true deducts the mining fee from this amount, preventing Core from creating a change address.

The command output returns the txid of the new transaction.

c. Confirm in a block Next, we mine another block to confirm the transaction.

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

d. Check the resulting UTXO

Finally, we can verify with listunspent:

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "828ec7cedc36f9517bd44a8e2a813be906698125c7c80b9a71a3202f2c09438c",
    "vout": 0,
    "address": "bcrt1qkyrgk8wkau455lytvggyp5wwtds2rr2m0f5kfg",
    "label": "",
    "scriptPubKey": "0014b1068b1dd6ef2b4a7c8b621040d1ce5b60a18d5b",
    "amount": 49.49998759,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/3]02759296d087fc8a6746c5949ccf44fb8c1ec84fd2898f0b3d636a1fb861f279e8)#grjvnzy9",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
...

Notice that we now have a new UTXO/txid with 49.49998759 BTC (49.49999859 BTC from the original UTXO minus 0.000011 BTC in fees).

3. Spending the entire amount with manual fee control

In this case, we want to send the entire UTXO balance to a single address without creating change, but setting the fee ourselves rather than having Core deduct it automatically.

The logic is simple: output value = input value - desired fee.

Thus, the difference between input and output is precisely the fee, and no change address is needed.

a. Prepare destination address

bitcoin-cli -datadir="." getnewaddress
# bcrt1qnpsadfag5mupmjyq3j8ksrr7rzxz6uawmpfuyk

b. Calculate the send amount

Suppose the available UTXO has 49.49998759 BTC (the UTXO from Scenario 2) and we want to pay a fee of 0.0001 BTC:

VALUE -> 49.49998759 - 0.0001
# 49.49988759

c. Create the raw transaction with the fee already deducted

bitcoin-cli -datadir="." createrawtransaction '[{"txid":"828ec7cedc36f9517bd44a8e2a813be906698125c7c80b9a71a3202f2c09438c","vout":0}]' '{"bcrt1qnpsadfag5mupmjyq3j8ksrr7rzxz6uawmpfuyk":49.49988759}'
# 02000000018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae00000000

The command returns a raw hex that leaves no room for change.

d. Sign

bitcoin-cli -datadir="." signrawtransactionwithwallet "02000000018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae00000000"
{
  "hex": "020000000001018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae0247304402200a243753e4417acd396221ef6461adf023b2c6b29a3fde1c87311c6bfc2863140220322ab5d37b10cf336c6f9ef4d504dfa7a7b1b5280680b790d0be42e7662ca1de012102759296d087fc8a6746c5949ccf44fb8c1ec84fd2898f0b3d636a1fb861f279e800000000",
  "complete": true
}

e. Send and confirm

bitcoin-cli -datadir="." sendrawtransaction "020000000001018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae0247304402200a243753e4417acd396221ef6461adf023b2c6b29a3fde1c87311c6bfc2863140220322ab5d37b10cf336c6f9ef4d504dfa7a7b1b5280680b790d0be42e7662ca1de012102759296d087fc8a6746c5949ccf44fb8c1ec84fd2898f0b3d636a1fb861f279e800000000"
# 647c2b177ddeeb222e339e69a3237bdaca71aad881a6a81d74591c6a120934b4

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

f. Verify the new UTXO

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "647c2b177ddeeb222e339e69a3237bdaca71aad881a6a81d74591c6a120934b4",
    "vout": 0,
    "address": "bcrt1qnpsadfag5mupmjyq3j8ksrr7rzxz6uawmpfuyk",
    "label": "",
    "scriptPubKey": "00149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae",
    "amount": 49.49988759,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/4]03df6d57b8af03faf7ff2aeee55347c397ea08756403d88d5d2981e546529939e8)#9xz6j0nm",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

Throughout these three scenarios, we have seen that even in a “simple” transaction, change is the crucial detail separating a safe operation from a costly mistake:

Scenario 1 — Partial spend: Core automatically creates a change address and calculates the fee.
Scenario 2 — Full sweep with subtractfeefromamount: Core deducts the fee directly from the output, avoiding change.
Scenario 3 — Full sweep with manual fee: you explicitly set input - output = fee, with no change.

If you ignore change—for example, by calling createrawtransaction where the sum of outputs is less than the sum of inputs and you neither add a change output nor use subtractfeefromamount—the entire difference becomes the miner fee.

On mainnet, this could mean losing a significant number of satoshis (or entire bitcoins) in a single transaction.

Therefore, always ask yourself before signing and broadcasting:

Do the outputs add up to exactly what I expect?
Am I letting Core handle the change, or did I manually adjust the output to account for the intended fee?

With this simple check, you ensure that every single satoshi goes to the right destination and avoid accidentally handing over the remainder to miners as an unintended fee.

Multi-Output Transactions (Batching)

A standard best practice for saving on fees and block space is sending funds to multiple recipients within a single transaction. This technique is known as batching and is widely adopted by exchanges and payment processors.

Instead of broadcasting separate transactions for each payout, we combine all outputs into a single raw transaction. The result is a single input (or a few selected inputs) funding multiple outputs, drastically lowering the overall fee because Bitcoin fees depend on transaction weight in virtual bytes (vbytes), not the monetary value transferred.

Let’s look at a practical walkthrough.

a. Prepare destination addresses Let’s generate two addresses to simulate different recipients:

bitcoin-cli -datadir="." getnewaddress
# bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n (Kaká)

bitcoin-cli -datadir="." getnewaddress
# bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks (Carol)

Suppose we have a UTXO of 49.49988759 BTC (the output from the previous scenario).

b. Create the raw transaction with multiple outputs We assign an amount for each recipient, for example:

Kaká: 0.7 BTC
Carol: 1.2 BTC

bitcoin-cli -datadir="." createrawtransaction   '[{"txid":"647c2b177ddeeb222e339e69a3237bdaca71aad881a6a81d74591c6a120934b4","vout":0}]' '{"bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n":0.7,
    "bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks":1.2}'
# 0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff02801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000

This command creates the raw hex with two outputs.

c. Fund with fee and change Since we are sending only 1.9 BTC out of the total, we need Core to calculate the fee and create a change address for the remaining balance.

bitcoin-cli -datadir="." fundrawtransaction "0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff02801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000" \
'{"feeRate":0.00001000}'
{
  "hex": "0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff03801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d876ba9b71b01000000160014a71ab94297573c130d6ea2f9aa25047903f57787000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000",
  "fee": 0.00000172,
  "changepos": 1
}

d. Sign and send

bitcoin-cli -datadir="." signrawtransactionwithwallet "0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff03801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d876ba9b71b01000000160014a71ab94297573c130d6ea2f9aa25047903f57787000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000"
{
  "hex": "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",
  "complete": true
}

bitcoin-cli -datadir="." sendrawtransaction "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"
# b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79

e. Confirm and inspect Mine a block to confirm:

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

List the UTXOs:

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 0,
    "address": "bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n",
    "label": "",
    "scriptPubKey": "0014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87",
    "amount": 0.70000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/5]039c8a99f8d6008801b97a6ec5f0ca231e706ddb28edebd12666b0f16aef7a48f2)#duqx02j9",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 1,
    "address": "bcrt1q5udtjs5h2u7pxrtw5tu65fgy0ypl2au8rkfg62",
    "scriptPubKey": "0014a71ab94297573c130d6ea2f9aa25047903f57787",
    "amount": 47.59988587,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/1/3]022a3cae7145dcfe74772d35b16fdb40e5fe0cf8fc3950eb5b9048a2b70d271e6f)#7uhj7gdg",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/1/*)#jtyys78l"
    ],
    "safe": true
  },
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 2,
    "address": "bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks",
    "label": "",
    "scriptPubKey": "0014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba64",
    "amount": 1.20000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/6]037994b04a5183d16e24f1a3a2a08bf1fcd5c528e5efcc3855065a6f3e0659ae0f)#ax5l0vfn",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

You will see three outputs (in addition to others not relevant here):

0.7 BTC to Kaká
1.2 BTC to Carol
The change (47.59988587) back to your wallet.

Why does batching save fees?

If you created two separate transactions—one for 0.7 BTC and another for 1.2 BTC—you would pay base transaction overhead twice, including two transaction headers, input signatures, and separate change outputs.

In transaction batching, the majority of transaction size comes from inputs; adding extra outputs has a much lower marginal byte cost.

UTXO Consolidation

Consolidation means combining multiple smaller UTXOs into a single, larger UTXO. Advantages: Future transactions will require fewer inputs (making them cheaper) and wallet state remains cleaner. Caution: Consolidation links those UTXOs together on-chain, creating a direct privacy impact (common-input ownership heuristic). Avoid co-mingling KYC and non-KYC funds, and schedule consolidations during periods of low mempool fee rates.

Let’s walk through a step-by-step guide to consolidating UTXOs.

a) Identify small UTXOs

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 0,
    "address": "bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n",
    "label": "",
    "scriptPubKey": "0014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87",
    "amount": 0.70000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/5]039c8a99f8d6008801b97a6ec5f0ca231e706ddb28edebd12666b0f16aef7a48f2)#duqx02j9",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 2,
    "address": "bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks",
    "label": "",
    "scriptPubKey": "0014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba64",
    "amount": 1.20000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/6]037994b04a5183d16e24f1a3a2a08bf1fcd5c528e5efcc3855065a6f3e0659ae0f)#ax5l0vfn",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e",
    "vout": 0,
    "address": "bcrt1qkqp9xzkre29gl7kl7d3s264nstysw7fqjj5pqf",
    "label": "",
    "scriptPubKey": "0014b002530ac3ca8a8ffadff363056ab382c9077920",
    "amount": 0.50000000,
    "confirmations": 4,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/1]0238caef26a2025d89d4230bcc7e2d1dbdcc8ce51ce1c07cd4509a76495bba07d9)#8q3llhqf",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  ...
]

Suppose we select these three UTXOs from the previous examples:

A: txid b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79, vout:0, 0.70000000 BTC
B: txid b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79, vout:2, 1.20000000 BTC
C: txid 1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e, vout:0, 0.50000000 BTC

Total = 2.40000000 BTC

b) Generate a wallet address to receive the consolidated funds

bitcoin-cli -datadir="." getnewaddress
# bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453

Option 1 — Using fundrawtransaction (no change via subtractFeeFromOutputs)

Simpler approach: you specify the total on the output and instruct Core to deduct the fee from that output, avoiding any change creation.

1. Create the raw hex with 3 inputs and 1 output (2.4 BTC)

bitcoin-cli -datadir="." createrawtransaction \
 '[{"txid":"b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79","vout":0},{"txid":"b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79","vout":2},{"txid":"1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e","vout":0}]' \
  '{"bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453":2.4}'
# 0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff01001c4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000

2. Fund: fee and no change

bitcoin-cli -datadir="." fundrawtransaction "0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff01001c4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000" \
  '{"add_inputs":false, "feeRate":0.00001000, "subtractFeeFromOutputs":[0]}'
#
{
  "hex": "0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff010b1b4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000",
  "fee": 0.00000245,
  "changepos": -1
}

A changepos value of -1 indicates that no change output was created.

3. Sign and send

bitcoin-cli -datadir="." signrawtransactionwithwallet "0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff010b1b4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000"
{
  "hex": "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",
  "complete": true
}

bitcoin-cli -datadir="." sendrawtransaction "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"
# 61db943161c00e8cf797cb8d4e3d896e88f52c8e39490e735d70abaa6a74ce73

4. Confirm and inspect the single consolidated UTXO

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "61db943161c00e8cf797cb8d4e3d896e88f52c8e39490e735d70abaa6a74ce73",
    "vout": 0,
    "address": "bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453",
    "label": "",
    "scriptPubKey": "00149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c1",
    "amount": 2.39999755,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/7]02b1f28fe1718cb0d19d63ca8f00f1da97a9ca6a2f2fe58ea38dc8764271fd9bb9)#v6xev5z7",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

Notice that we now have a single UTXO containing 2.39999755 BTC (2.4 consolidated BTC minus the mining fee).

Option 2 — Full manual control (without fundrawtransaction) We can specify our own fee directly and set the output value as sum(inputs) - fee (leaving no change). In this scenario, we will consolidate 3 UTXOs received from mining rewards in previous examples.

1. Calculate the output amount

VALUE=150-(0.0001)
VALUE=149.9999

2. Create the raw transaction with no change output

bitcoin-cli -datadir="." createrawtransaction \
'[{"txid":"347775cd427f4e7b88906ce5ca8c11570822063c76280cc2e63879e6ed956323","vout":0},{"txid":"cebd41bfe9964f604f7247ee0c27a1bec23a55880c5be1c91b3889f4e2277808","vout":0},{"txid":"1a2c538fb7b78a8898ddc82b79dd593922d402153c7ff97491e539a91b57fde7","vout":0}]' \
  '{"bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453":149.9999}'
# 0200000003236395ede67938e6c20c28763c06220857118ccae56c90887b4e7f42cd7577340000000000fdffffff087827e2f489381bc9e15b0c88553ac2bea1270cee47724f604f96e9bf41bdce0000000000fdffffffe7fd571ba939e59174f97f3c1502d4223959dd792bc8dd98888ab7b78f532c1a0000000000fdffffff01f0ae117e030000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000

3. Sign, send, and confirm

bitcoin-cli -datadir="." signrawtransactionwithwallet "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"
{
  "hex": "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",
  "complete": true
}

bitcoin-cli -datadir="." sendrawtransaction "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"
# 2c668e312971983fc465d8c79f5813732f288331cda23dd86fd73fc5339e2984

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

We can list our UTXOs to verify the consolidation.

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "2c668e312971983fc465d8c79f5813732f288331cda23dd86fd73fc5339e2984",
    "vout": 0,
    "address": "bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453",
    "label": "",
    "scriptPubKey": "00149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c1",
    "amount": 149.99990000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/7]02b1f28fe1718cb0d19d63ca8f00f1da97a9ca6a2f2fe58ea38dc8764271fd9bb9)#v6xev5z7",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

Notice that we now have a single UTXO containing 149.99990000 BTC.

Constructing transactions manually in Bitcoin Core is far more than an intellectual exercise: it is a hands-on laboratory for understanding the protocol. Throughout this article, we covered scenarios ranging from basic sends with automatic change handling to more advanced strategies such as batching and UTXO consolidation.

These examples highlight several essential truths:

Every satoshi matters — neglecting fee calculations or change output definitions can turn an oversight into an exorbitant miner fee.
Control is power — manually selecting inputs, determining fee rates, and deciding when to consolidate UTXOs allows you to minimize on-chain expenses and keep your wallet orderly.
Privacy requires deliberate planning — consolidating or co-spending UTXOs reveals common-ownership links across addresses. In production environments, always pair these techniques with solid privacy practices.

Practicing these commands on regtest or signet provides the safety of a sandbox, but the knowledge translates directly to mainnet. Before broadcasting transactions with real funds, always verify:

Sum of outputs vs. inputs — ensure the discrepancy equals your intended mining fee.
Change destination — verify the change address is under your control, or use subtractfeefromamount when sweeping outputs.
Mempool fee rates — adjust fees according to current network congestion to balance cost and confirmation priority.

Mastering these workflows gives you not only the confidence to operate directly on the Bitcoin network, but also a profound understanding of the UTXO model that powers it.

In subsequent articles, we will explore advanced transaction techniques including Partially Signed Bitcoin Transactions (PSBTs), multisig wallets, and timelocks.

Construindo Transações no Bitcoin Core

2026-10-12T00:00:00+00:00

Construindo Transações no Bitcoin Core

por Rafael Santos

No artigo anterior exploramos a anatomia de uma transação no Bitcoin, entendendo como os inputs e outputs se conectam ao modelo UTXO e como o Bitcoin Core pode lidar com diferentes níveis de automação, desde a criação totalmente automática até a montagem bruta de um hex. Essa visão foi essencial para compreender a lógica interna do protocolo e perceber como cada parte da transação tem um papel fundamental na validação pela rede.

Agora, daremos um passo além: o objetivo deste artigo é aprender a criar transações de diferentes tipos e cenários, colocando em prática a construção manual com o Bitcoin Core. Vamos começar com exemplos simples e explorar situações reais, como o envio para múltiplos destinatários (batching), a criação de transações com troco, a consolidação de UTXOs e o controle manual das taxas.

Para dominar a criação de transações no Bitcoin Core, é importante ir além do caso mais simples e experimentar diferentes cenários que refletem situações reais de uso. Cada um deles pode nos ensinar algo específico sobre como o protocolo funciona e como podemos ter maior controle sobre nossos UTXOs e taxas.

Utilizaremos nesse artigo a rede regtest, nao esqueça de configurar o arquivo bitcoin.conf. Você pode usar a signet também, apenas vai ter que esperar os sBTC entrarem depois de solicitar no faucet.

Transação simples e o papel do troco

Esse é o exemplo mais básico: gastar um único UTXO para enviar fundos a apenas um destinatário. Mas mesmo na “transação simples”, temos nuances importantes a considerar. Caso não tenha nenhum UTXO, crie um endereço para sua carteira e minere 101 blocos (pra tornar gastável):

bitcoin-cli -datadir="." getnewaddress
# bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p

bitcoin-cli -datadir="." generatetoaddress 101 bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p

Agora, em primeiro lugar, listamos os UTXOs disponíveis na carteira:

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "c3fef1a9764c57262ef70c2f11eb5bf548cbbcaeb7d900a77ae9ac25cb3954de",
    "vout": 0,
    "address": "bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p",
    "label": "",
    "scriptPubKey": "0014f4d71c42d89f7c185c7c2d56a86968484c026ff6",
    "amount": 50.00000000,
    "confirmations": 101,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/0]024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba7)#ah5fng3d",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  }
]

Neste caso, temos um UTXO com 50 BTCs para gastar. Vamos ver alguns cenários.

1. Enviar parte do valor, deixando o Core criar troco

Aqui vamos supor que queremos mandar 0.5 BTC e deixar o Core calcular taxa e gerar endereço de troco.

a. Criar o hex bruto sem taxa nem troco

bitcoin-cli -datadir="." createrawtransaction   '[{"txid":"c3fef1a9764c57262ef70c2f11eb5bf548cbbcaeb7d900a77ae9ac25cb3954de","vout":0}]'   '{"bcrt1qkqp9xzkre29gl7kl7d3s264nstysw7fqjj5pqf":0.5}'
0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0180f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c907792000000000

b. Completar com taxa e troco automático

Esse Hex gerado acima é utilizado no comando fundrawtransaction, que completa a transação com a taxa e o troco.

bitcoin-cli -datadir="." fundrawtransaction "0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0180f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c907792000000000"  '{"feeRate":0.00001000}'
{
  "hex": "0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a472700000000",
  "fee": 0.00000141,
  "changepos": 1
}

Um novo valor Hex é gerado, agora representado a transação completa.

c. Assinar e enviar

bitcoin-cli -datadir="." signrawtransactionwithwallet "0200000001de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a472700000000"
{
  "hex": "02000000000101de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a4727024730440220139015403f1787b993f84616a737c4a51ac93976cae845e1bc3949a8245a21c702200fa867025026dd8a624896265bf9c44130d87c49845a4251f3917e79a042f87b0121024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba700000000",
  "complete": true
}

O signrawtransactionwithwallet assina a transação e o sendrawtransaction envia para a rede.

bitcoin-cli -datadir="." sendrawtransaction "02000000000101de5439cb25ace97aa700d9b7aebccb48f55beb112f0cf72e26574c76a9f1fec30000000000fdffffff0280f0fa0200000000160014b002530ac3ca8a8ffadff363056ab382c9077920f3000b2701000000160014fcde2eebcd45d4e852907d8de7051e5a9e9a4727024730440220139015403f1787b993f84616a737c4a51ac93976cae845e1bc3949a8245a21c702200fa867025026dd8a624896265bf9c44130d87c49845a4251f3917e79a042f87b0121024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba700000000"
1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e

Logo após, mineramos mais um bloco para confirmar a transação enviada.

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

Então podemos observar nosso UTXO mais uma vez.

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "b260fe7dd4eac4dca8b70d58e8cff68fb3f5753a61dc0856e658bbe731736c90",
    "vout": 0,
    "address": "bcrt1q7nt3cskcna7pshru94t2s6tgfpxqymlkp0eh6p",
    "label": "",
    "scriptPubKey": "0014f4d71c42d89f7c185c7c2d56a86968484c026ff6",
    "amount": 50.00000000,
    "confirmations": 101,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/0]024bdbdf6b6c264db5a9a9f2ffb6f964f228c722c419ffd7ae26a7b850bfce6ba7)#ah5fng3d",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e",
    "vout": 0,
    "address": "bcrt1qkqp9xzkre29gl7kl7d3s264nstysw7fqjj5pqf",
    "label": "",
    "scriptPubKey": "0014b002530ac3ca8a8ffadff363056ab382c9077920",
    "amount": 0.50000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/1]0238caef26a2025d89d4230bcc7e2d1dbdcc8ce51ce1c07cd4509a76495bba07d9)#8q3llhqf",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e",
    "vout": 1,
    "address": "bcrt1qln0za67dgh2ws55s0kx7wpg7t20f53e8envezx",
    "scriptPubKey": "0014fcde2eebcd45d4e852907d8de7051e5a9e9a4727",
    "amount": 49.49999859,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/1/0]03f032737bcfe1ccb7cf642458916102c22386727a2e3be2f36cdc4cb6ab37c3b9)#nyyqzwmx",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/1/*)#jtyys78l"
    ],
    "safe": true
  }
]

Perceba que temos 3 UTXO, o primeiro é referente a recompensa dessa nova mineração que acabamos de fazer, então podemos ignorar aqui. O segundo UTXO é referente ao endereço pra qual mandamos a transação. Já o terceiro, é o endereço de troco gerado na transação, e possui 49.49999859 BTC (50 dos BTC originais - 0,5 enviados - taxa).

2. Gastar todo o valor, subtraindo a taxa automaticamente

Neste caso, queremos enviar todo o saldo do UTXO para um único endereço, sem gerar endereço de troco.

O Bitcoin Core permite que a própria taxa seja descontada do valor de envio, de forma que o output final já considere a taxa de mineração.

a. Criar endereço de destino

bitcoin-cli -datadir="." getnewaddress
#bcrt1qkyrgk8wkau455lytvggyp5wwtds2rr2m0f5kfg

b. Enviar todo o saldo, subtraindo a taxa Podemos usar o comando sendtoaddress com o parâmetro subtractfeefromamount=true para enviar todo saldo de um UTXO:

bitcoin-cli -datadir="." sendtoaddress \
  bcrt1qkyrgk8wkau455lytvggyp5wwtds2rr2m0f5kfg \
  49.49999859 \
  "" "" \
  true
#828ec7cedc36f9517bd44a8e2a813be906698125c7c80b9a71a3202f2c09438c

O valor de 49.49999859 BTC corresponde ao UTXO de troco que recebemos no cenário anterior.
O último argumento true faz com que a taxa de mineração seja descontada desse valor, evitando que o Core crie um endereço de troco.

A saída do comando já retorna o txid da nova transação.

d. Confirmar em bloco Em seguida podemos minerar novamente para confirmar em um bloco.

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

e. Checar UTXO resultante

Por fim, podemos conferir com o listunspent:

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "828ec7cedc36f9517bd44a8e2a813be906698125c7c80b9a71a3202f2c09438c",
    "vout": 0,
    "address": "bcrt1qkyrgk8wkau455lytvggyp5wwtds2rr2m0f5kfg",
    "label": "",
    "scriptPubKey": "0014b1068b1dd6ef2b4a7c8b621040d1ce5b60a18d5b",
    "amount": 49.49998759,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/3]02759296d087fc8a6746c5949ccf44fb8c1ec84fd2898f0b3d636a1fb861f279e8)#grjvnzy9",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
...

Note que agora temos um novo UTXO/txid com 49.49998759 BTC (49.49999859 BTC do UTXO Original - 0,000011 BTC da taxa).

3. Gastar todo o valor ajustando a taxa manualmente

Neste caso, queremos enviar todo o saldo de um UTXO para um único endereço sem gerar troco, mas definindo nós mesmos a taxa em vez de deixar o Core subtrair automaticamente.

A lógica é simples: valor do output = valor do input – taxa desejada.

Assim, a diferença entre entrada e saída é exatamente a taxa, e nenhum endereço de troco é necessário.

a. Preparar o endereço de destino

bitcoin-cli -datadir="." getnewaddress
# bcrt1qnpsadfag5mupmjyq3j8ksrr7rzxz6uawmpfuyk

b. Calcular o valor de envio

Suponha que o UTXO disponível seja de 49.49998759 BTC (UTXO do cenário 2) e queremos pagar uma taxa de 0.0001 BTC:

VALOR -> 49.49998759 - 0.0001
# 49.49988759

c. Criar a transação bruta com valor já descontado

bitcoin-cli -datadir="." createrawtransaction '[{"txid":"828ec7cedc36f9517bd44a8e2a813be906698125c7c80b9a71a3202f2c09438c","vout":0}]' '{"bcrt1qnpsadfag5mupmjyq3j8ksrr7rzxz6uawmpfuyk":49.49988759}'
# 02000000018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae00000000

O comando retorna um hex bruto que já não terá espaço para troco.

d. Assinar

bitcoin-cli -datadir="." signrawtransactionwithwallet "02000000018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae00000000"
{
  "hex": "020000000001018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae0247304402200a243753e4417acd396221ef6461adf023b2c6b29a3fde1c87311c6bfc2863140220322ab5d37b10cf336c6f9ef4d504dfa7a7b1b5280680b790d0be42e7662ca1de012102759296d087fc8a6746c5949ccf44fb8c1ec84fd2898f0b3d636a1fb861f279e800000000",
  "complete": true
}

e. Enviar e confirmar

bitcoin-cli -datadir="." sendrawtransaction "020000000001018c43092c2f20a3719a0bc8c725816906e93b812a8e4ad47b51f936dccec78e820000000000fdffffff0197d50a27010000001600149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae0247304402200a243753e4417acd396221ef6461adf023b2c6b29a3fde1c87311c6bfc2863140220322ab5d37b10cf336c6f9ef4d504dfa7a7b1b5280680b790d0be42e7662ca1de012102759296d087fc8a6746c5949ccf44fb8c1ec84fd2898f0b3d636a1fb861f279e800000000"
# 647c2b177ddeeb222e339e69a3237bdaca71aad881a6a81d74591c6a120934b4

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

f. Conferir o novo UTXO

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "647c2b177ddeeb222e339e69a3237bdaca71aad881a6a81d74591c6a120934b4",
    "vout": 0,
    "address": "bcrt1qnpsadfag5mupmjyq3j8ksrr7rzxz6uawmpfuyk",
    "label": "",
    "scriptPubKey": "00149861d6a7a8a6f81dc8808c8f680c7e188c2d73ae",
    "amount": 49.49988759,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/4]03df6d57b8af03faf7ff2aeee55347c397ea08756403d88d5d2981e546529939e8)#9xz6j0nm",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

Ao longo desses três cenários vimos que, mesmo em uma transação “simples”, o troco é o detalhe que separa uma operação segura de um erro caro:

Cenário 1 – Envio parcial: o Core cria automaticamente um endereço de troco e calcula a taxa.
Cenário 2 – Envio total com subtractfeefromamount: o Core deduz a taxa do próprio output, evitando troco.
Cenário 3 – Envio total com taxa manual: você mesmo define input – output = taxa, sem troco.

Se você ignora o troco, por exemplo, cria um createrawtransaction onde a soma dos outputs é menor que a soma dos inputs e não adiciona nem troco nem subtractfeefromamount, toda a diferença vira taxa de mineração.

Em mainnet isso pode significar perder muitos satoshis (ou bitcoins) em uma única transação.

Por isso, sempre se pergunte antes de assinar e transmitir:

Os outputs somam exatamente o que eu espero?
Estou deixando o Core cuidar do troco ou ajustei o valor manualmente para a taxa desejada?

Com essa checagem simples, você garante que cada satoshi vá para o destino certo e evita que “o resto” acabe nas mãos dos mineradores como taxa involuntária.

Transação com múltiplos outputs (batching)

Uma prática comum para economizar taxas e espaço em bloco é enviar fundos para vários destinatários dentro de uma única transação. Esse método é conhecido como batching e é amplamente utilizado por exchanges e serviços de pagamento.

Em vez de criar várias transações, uma para cada pagamento, reunimos todos os outputs em um só raw transaction. O resultado é um único input (ou alguns inputs selecionados) alimentando vários outputs, reduzindo a taxa total, pois ela depende principalmente do tamanho em vbytes e não do valor transferido.

Vamos ver em um caso prático.

a. Preparar os endereços de destino Vamos criar dois endereços para simular destinatários diferentes:

bitcoin-cli -datadir="." getnewaddress
# bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n (Kaká)

bitcoin-cli -datadir="." getnewaddress
# bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks (Carol)

Suponha que temos um UTXO de 49.49988759 BTC (resultado do cenário anterior).

b. Criar a transação bruta com múltiplos outputs Definimos um valor para cada destinatário, por exemplo:

Kaká: 0.7 BTC
Carol: 1.2 BTC

bitcoin-cli -datadir="." createrawtransaction   '[{"txid":"647c2b177ddeeb222e339e69a3237bdaca71aad881a6a81d74591c6a120934b4","vout":0}]' '{"bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n":0.7,
    "bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks":1.2}'
# 0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff02801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000

Esse comando cria o hex bruto com dois outputs.

c. Completar com taxa e troco Como estamos enviando apenas 1.9 BTC do total, precisamos que o Core calcule a taxa e crie o endereço de troco para o restante.

bitcoin-cli -datadir="." fundrawtransaction "0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff02801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000" \
'{"feeRate":0.00001000}'
{
  "hex": "0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff03801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d876ba9b71b01000000160014a71ab94297573c130d6ea2f9aa25047903f57787000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000",
  "fee": 0.00000172,
  "changepos": 1
}

d. Assinar e enviar

bitcoin-cli -datadir="." signrawtransactionwithwallet "0200000001b43409126a1c59741da8a681d8aa71cada7b23a3699e332e22ebde7d172b7c640000000000fdffffff03801d2c0400000000160014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d876ba9b71b01000000160014a71ab94297573c130d6ea2f9aa25047903f57787000e270700000000160014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba6400000000"
{
  "hex": "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",
  "complete": true
}

bitcoin-cli -datadir="." sendrawtransaction "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"
# b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79

e. Confirmar e inspecionar Minerar um bloco para confirmar:

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

Liste os UTXOs:

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 0,
    "address": "bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n",
    "label": "",
    "scriptPubKey": "0014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87",
    "amount": 0.70000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/5]039c8a99f8d6008801b97a6ec5f0ca231e706ddb28edebd12666b0f16aef7a48f2)#duqx02j9",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 1,
    "address": "bcrt1q5udtjs5h2u7pxrtw5tu65fgy0ypl2au8rkfg62",
    "scriptPubKey": "0014a71ab94297573c130d6ea2f9aa25047903f57787",
    "amount": 47.59988587,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/1/3]022a3cae7145dcfe74772d35b16fdb40e5fe0cf8fc3950eb5b9048a2b70d271e6f)#7uhj7gdg",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/1/*)#jtyys78l"
    ],
    "safe": true
  },
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 2,
    "address": "bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks",
    "label": "",
    "scriptPubKey": "0014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba64",
    "amount": 1.20000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/6]037994b04a5183d16e24f1a3a2a08bf1fcd5c528e5efcc3855065a6f3e0659ae0f)#ax5l0vfn",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

Você verá três outputs (além de outros que não nos interessante aqui):

0.7 BTC para Kaká
1.2 BTC para Carol
O troco (47.59988587) de volta para a sua carteira.

Por que o batching economiza?

Se você criasse duas transações separadas, uma de 0.7 BTC e outra de 1.2 BTC, pagaria taxa duas vezes e criaria dois cabeçalhos, duas assinaturas etc.

No batching, a maior parte do tamanho da transação está nos inputs; aumentar apenas os outputs tem custo marginal bem menor.

Consolidação de UTXOs

Consolidar é juntar vários UTXOs pequenos em um único UTXO maior. Vantagens: transações futuras com menos inputs (mais baratas) e carteira mais simples. Cuidado: consolidação liga aqueles UTXOs entre si (impacto de privacidade). Evite misturar KYC/non-KYC e prefira fazer quando as taxas estão baixas.

Vamos a um passo-a-passo para consolidar UTXOs.

a) Identificar UTXOs pequenos

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 0,
    "address": "bcrt1q7waheqekh39xlscz5ct28dqhhhh0u8v8nwh42n",
    "label": "",
    "scriptPubKey": "0014f3bb7c8336bc4a6fc302a616a3b417bdeefe1d87",
    "amount": 0.70000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/5]039c8a99f8d6008801b97a6ec5f0ca231e706ddb28edebd12666b0f16aef7a48f2)#duqx02j9",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79",
    "vout": 2,
    "address": "bcrt1qllxahh4su69rszmyjr93y3t07h57nwny0j95ks",
    "label": "",
    "scriptPubKey": "0014ffcddbdeb0e68a380b6490cb12456ff5e9e9ba64",
    "amount": 1.20000000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/6]037994b04a5183d16e24f1a3a2a08bf1fcd5c528e5efcc3855065a6f3e0659ae0f)#ax5l0vfn",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
    "txid": "1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e",
    "vout": 0,
    "address": "bcrt1qkqp9xzkre29gl7kl7d3s264nstysw7fqjj5pqf",
    "label": "",
    "scriptPubKey": "0014b002530ac3ca8a8ffadff363056ab382c9077920",
    "amount": 0.50000000,
    "confirmations": 4,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/1]0238caef26a2025d89d4230bcc7e2d1dbdcc8ce51ce1c07cd4509a76495bba07d9)#8q3llhqf",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  ...
]

Suponha que escolhemos esses três UTXOs resultantes dos exemplos anteriores:

A: txid b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79, vout:0, 0.70000000 BTC
B: txid b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79, vout:2, 1.20000000 BTC
C: txid 1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e, vout:0, 0.50000000 BTC

Total = 2.40000000 BTC

b) Gerar um endereço seu para receber a consolidação

bitcoin-cli -datadir="." getnewaddress
# bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453

Opção 1 — Com fundrawtransaction (sem troco via subtractFeeFromOutputs)

Mais simples: você informa o total na saída e pede para a taxa ser descontada do próprio output, evitando troco.

1. Criar o hex bruto com 3 inputs e 1 output (2.4 BTC)

bitcoin-cli -datadir="." createrawtransaction \
 '[{"txid":"b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79","vout":0},{"txid":"b9554be708c5ea7414876a3757a65df19cd5ddf8c19365c8425c3f8ce8066d79","vout":2},{"txid":"1417f599358ea49a63dd253a3b3701ce0fa28cdf006522e4a3c50c48fce12e8e","vout":0}]' \
  '{"bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453":2.4}'
# 0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff01001c4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000

2. Completar: taxa e “sem troco”

bitcoin-cli -datadir="." fundrawtransaction "0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff01001c4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000" \
  '{"add_inputs":false, "feeRate":0.00001000, "subtractFeeFromOutputs":[0]}'
#
{
  "hex": "0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff010b1b4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000",
  "fee": 0.00000245,
  "changepos": -1
}

changepos igual a -1 indica que não há troco. 3. Assinar e enviar

bitcoin-cli -datadir="." signrawtransactionwithwallet "0200000003796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff010b1b4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000"
{
  "hex": "02000000000103796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90000000000fdffffff796d06e88c3f5c42c86593c1f8ddd59cf15da657376a871474eac508e74b55b90200000000fdffffff8e2ee1fc480cc5a3e4226500df8ca20fce01373b3a25dd639aa48e3599f517140000000000fdffffff010b1b4e0e000000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c10247304402203664d96a5f91c916e213e9a6adabda0c4a2031abe9db7e1a8f2f996f9fdbad91022070ea8353ce9281456776f5e723c48c1aa022a4adb35a207f9644c0338d95c6310121039c8a99f8d6008801b97a6ec5f0ca231e706ddb28edebd12666b0f16aef7a48f20247304402203c350e5bd7a9a69fde895df1ae95d6935383c7ac7554f53ac10437391d45d3fd02202fbfc490b365afe774bb4771650ec9bb81e813a6df547e523ed9bacf4fa1d6f50121037994b04a5183d16e24f1a3a2a08bf1fcd5c528e5efcc3855065a6f3e0659ae0f0247304402206e422304d7a85fb96a9624c532cabd2ae0354711554410b7360cff55df14a57e02202bdbd8fb1983d5d3f24f859f735c11b174bfea9a5b813e77e8a9734047620a7001210238caef26a2025d89d4230bcc7e2d1dbdcc8ce51ce1c07cd4509a76495bba07d900000000",
  "complete": true
}

bitcoin-cli -datadir="." sendrawtransaction "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"
# 61db943161c00e8cf797cb8d4e3d896e88f52c8e39490e735d70abaa6a74ce73

4. Confirmar e verificar o novo UTXO único

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "61db943161c00e8cf797cb8d4e3d896e88f52c8e39490e735d70abaa6a74ce73",
    "vout": 0,
    "address": "bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453",
    "label": "",
    "scriptPubKey": "00149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c1",
    "amount": 2.39999755,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/7]02b1f28fe1718cb0d19d63ca8f00f1da97a9ca6a2f2fe58ea38dc8764271fd9bb9)#v6xev5z7",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

Perceba que agora temos um UTXO com 2.39999755 BTC (2.4 BTC consolidados - taxa).

Opção 2 — Total controle (sem fundrawtransaction) Podemos definir a taxa e já criar a saída como soma(inputs) − taxa (sem troco). Nesse cenário, vamos consolidar 3 UTXOs que receberam as recompensas de mineração em exemplos anteriores.

1. Calcular o valor de saída

VALOR=150-(0.0001)
VALOR=149.9999

2. Criar o raw sem espaço para troco

bitcoin-cli -datadir="." createrawtransaction \
'[{"txid":"347775cd427f4e7b88906ce5ca8c11570822063c76280cc2e63879e6ed956323","vout":0},{"txid":"cebd41bfe9964f604f7247ee0c27a1bec23a55880c5be1c91b3889f4e2277808","vout":0},{"txid":"1a2c538fb7b78a8898ddc82b79dd593922d402153c7ff97491e539a91b57fde7","vout":0}]' \
  '{"bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453":149.9999}'
# 0200000003236395ede67938e6c20c28763c06220857118ccae56c90887b4e7f42cd7577340000000000fdffffff087827e2f489381bc9e15b0c88553ac2bea1270cee47724f604f96e9bf41bdce0000000000fdffffffe7fd571ba939e59174f97f3c1502d4223959dd792bc8dd98888ab7b78f532c1a0000000000fdffffff01f0ae117e030000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000

3. Assinar, enviar e confirmar

bitcoin-cli -datadir="." signrawtransactionwithwallet "0200000003236395ede67938e6c20c28763c06220857118ccae56c90887b4e7f42cd7577340000000000fdffffff087827e2f489381bc9e15b0c88553ac2bea1270cee47724f604f96e9bf41bdce0000000000fdffffffe7fd571ba939e59174f97f3c1502d4223959dd792bc8dd98888ab7b78f532c1a0000000000fdffffff01f0ae117e030000001600149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c100000000"
{
  "hex": "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",
  "complete": true
}

bitcoin-cli -datadir="." sendrawtransaction "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"
# 2c668e312971983fc465d8c79f5813732f288331cda23dd86fd73fc5339e2984

bitcoin-cli -datadir="." generatetoaddress 1 bcrt1q9w437k3luux5crekejss56r8cysxhr4ypuha22

Podemos listar os UTXOs para conferir a consolidação.

bitcoin-cli -datadir="." listunspent
[
  {
    "txid": "2c668e312971983fc465d8c79f5813732f288331cda23dd86fd73fc5339e2984",
    "vout": 0,
    "address": "bcrt1qnk9lxpt4ch7zkp9ncdr3awe0aa0e49kp5v6453",
    "label": "",
    "scriptPubKey": "00149d8bf30575c5fc2b04b3c3471ebb2fef5f9a96c1",
    "amount": 149.99990000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "wpkh([2f5cd395/84h/1h/0h/0/7]02b1f28fe1718cb0d19d63ca8f00f1da97a9ca6a2f2fe58ea38dc8764271fd9bb9)#v6xev5z7",
    "parent_descs": [
      "wpkh(tpubD6NzVbkrYhZ4WtpQ21uY5dQCNe2wu8GdTcB7zLmVcdvJPFjQ8c4FNq1wR4zsr1qc1XgZqVAmd6m6uHrSJhrfTHsy5cnw5yyQaWG49guuByL/84h/1h/0h/0/*)#rlp9dth8"
    ],
    "safe": true
  },
  {
  ...

Veja que agora temos um UTXO com 149.99990000 BTC.

Construir transações manualmente no Bitcoin Core é mais do que um exercício de curiosidade: é um laboratório prático para entender o protocolo. Ao longo deste artigo, vimos cenários que cobrem desde o envio básico com troco automático até estratégias mais avançadas como batching e consolidação de UTXOs.

Esses exemplos deixam claro que:

Cada satoshi importa – negligenciar o cálculo de taxas ou o endereço de troco pode transformar uma simples distração em uma taxa gigantesca paga ao minerador.
Controle é poder – escolher manualmente os inputs, definir a taxa e decidir quando consolidar UTXOs permite otimizar custos e simplificar a carteira.
Privacidade exige planejamento – consolidar ou misturar UTXOs pode revelar vínculos entre endereços. Em ambientes de produção, combine estas técnicas com boas práticas de privacidade.

Praticar esses comandos em regtest ou signet fornece a segurança de um ambiente controlado, mas o aprendizado é diretamente aplicável à mainnet. Antes de enviar transações reais, revise sempre:

Soma dos outputs vs. inputs – garanta que a diferença seja a taxa pretendida.
Destino do troco – defina um endereço sob seu controle ou use subtractfeefromamount se quiser evitá-lo.
Taxa de rede – ajuste de acordo com o mempool para equilibrar custo e velocidade de confirmação.

Dominar essas práticas dá a você não apenas confiança para operar na rede, mas também uma compreensão profunda do modelo UTXO que sustenta o Bitcoin.

Nos próximos artigos, exploraremos outras questões avançadas relacionadas à transações, como PSBTs (Partially Signed Bitcoin Transactions), multisig e timelocks. **

BitDevs Maputo

Socratic Seminar 01: Who Really Runs Bitcoin?

Location

Announcements

Reminders

Topics

Opening

Introduction

Bitcoin Core

Private & Public Keys

Addresses & Transactions

Closing & Upcoming Events

Seminário Socrático 01: Quem manda realmente no Bitcoin?

Local

Anúncios

Lembretes

Temas

Abertura

Apresentação

Bitcoin Core

Chaves Privadas e Públicas

Entropia

Endereços e Transações

Encerramento e Próximos Eventos

Protect Your Bitcoin Like Satoshi

Protect Your Bitcoin Like Satoshi: A Guide to Cold Storage with an Air-Gapped Laptop

Introduction and Philosophy

Why Consider an Air-Gapped Laptop?

1. Control Over Software and Hardware

2. Privacy

3. Technological Independence

What Does Air-Gapped Mean?

Implementation Roadmap: Five Stages

Episode 1 — Hardware and Security Philosophy

Episode 2 — Communication Isolation

Episode 3 — Operating System and Bitcoin Software

Episode 4 — Key Generation and Offline Signing

Episode 5 — Backups and Long-Term Preservation

Hardware Selection: Lenovo ThinkPad T530

Security: What You Should Never Ignore

Conclusion

Proteja o seu Bitcoin como Satoshi

Proteja o seu Bitcoin como Satoshi: Guia de Cold Storage com Portátil Air-Gapped

Introdução e filosofia

Por que considerar um portátil air-gapped?

1. Controlo sobre o software e o hardware

2. Privacidade

3. Independência tecnológica

O que significa air-gapped?

Roteiro de implementação: cinco etapas

Episódio 1 — Hardware e filosofia de segurança

Episódio 2 — Isolamento das comunicações

Episódio 3 — Sistema operativo e software Bitcoin

Episódio 4 — Geração de chaves e assinatura offline

Episódio 5 — Cópias de segurança e preservação de longo prazo

Escolha do hardware: Lenovo ThinkPad T530

Segurança: o que não deves ignorar

Conclusão

The Magic of Key Multiplication: Understanding BIP32 in Bitcoin

The Magic of Key Multiplication: Understanding BIP32 in Bitcoin

Introduction

What Is a Bitcoin Improvement Proposal (BIP)?

The Evolution of Bitcoin Key Management

1. The Cryptographic Foundation

2. The Original Problem: Address Reuse and Endless Backups

The BIP32 Solution: Hierarchical Deterministic Wallets

The Mathematics Behind Public Key Derivation

A Practical Demonstration in Python

Extended Keys: xprv and xpub

xprv — Extended Private Key

xpub — Extended Public Key

BIP32 and BIP39: Understanding the Difference

Conclusion

A Magia da Multiplicação de Chaves: Entendendo a BIP32

A Magia da Multiplicação de Chaves: Entendendo a BIP32 no Bitcoin

Introdução

O que é uma BIP (Bitcoin Improvement Proposal)?

A evolução da gestão de chaves no Bitcoin

1. A base criptográfica

2. O problema original: reutilização de endereços e cópias de segurança infinitas

Extended Keys: `xprv` and `xpub`

`xprv` — Extended Private Key

`xpub` — Extended Public Key

Chaves estendidas: `xprv` e `xpub`

`xprv` — Chave privada estendida

`xpub` — Chave pública estendida