Partially Signed Bitcoin Transaction

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Pronunciation

[par-shuh-lee sīd bit-koin tranz-ak-shun]

Analogy

Like a contract circulated among signatories—each adds their signature before it becomes valid.

Definition

PSBT: a standardized format (BIP-174) for transactions that allows multiple parties or devices to add signatures in sequence.

Key Points Intro

PSBTs facilitate multi-step signing via:

Key Points

Structured fields: Inputs, outputs, partial signatures.

Multi‑sig & offline: Supports hardware and multi-party workflows.

Tool integration: Used by Electrum, hardware wallets.

Non-final: Can be passed around until fully signed.

Example

A 2-of-3 multisig PSBT is created by an online server, signed by two hardware wallets offline, then broadcast by the server.

Technical Deep Dive

PSBT is a serialized map of key-value pairs: global unsigned , per-input data, HD key paths, partial sigs. `PSBT_IN_PARTIAL_SIG` fields accumulate until input is fully signed.

Security Warning

Incomplete PSBTs should not be broadcast; ensure all required signatures present.

Caveat

Not all wallets support PSBT v2 features; compatibility may vary.

Related Terms

Offline Signing

HD Wallet

Cold Storage

Blockchain & Cryptocurrency Glossary

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