# Bitcoin multisig: what a two-of-three wallet actually requires A Bitcoin multisignature arrangement makes a spend require a specified threshold of signatures from an authorized key set. In a two-of-three example, two qualifying keys can authorize the spend. Its resilience depends on how keys, devices, recovery information and decision authority are actually separated. Evidence: [Bitcoin Developer Guide: Transactions](https://developer.bitcoin.org/devguide/transactions.html); [Partially Signed Bitcoin Transaction Format](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0174.mediawiki) Canonical: https://degreesofsatoshi.com/encyclopedia/bitcoin-multisig/ Published: 2026-10-02 Substantively modified: 2026-10-02 Independently verified by an automated reviewer: 2026-10-02T18:15:23.891Z Data current through: 2026-10-02 AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied. ## Key facts - **Threshold:** Two-of-three requires two authorized signatures, not all three. ([Bitcoin Developer Guide: Transactions](https://developer.bitcoin.org/devguide/transactions.html)) - **Coordination:** A PSBT can carry transaction details between participants before finalization. ([Partially Signed Bitcoin Transaction Format](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0174.mediawiki)) - **Backup:** The spending script and key information matter as well as private-key backups. ([Output Script Descriptors General Operation](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0380.mediawiki); [Partially Signed Bitcoin Transaction Format](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0174.mediawiki)) ## Follow a two-of-three decision Label three authorized keys A, B and C. A policy requiring two permits A+B, A+C or B+C. A alone is insufficient. If a party controls both A and B, the arrangement does not require agreement from two independent people. Multisignature describes an authorization rule, not a business structure. Device separation, custody agreements and organizational processes determine how that rule is used. Evidence: [Bitcoin Developer Guide: Transactions](https://developer.bitcoin.org/devguide/transactions.html) ## What each signer should inspect A partially signed transaction can carry the proposed inputs, outputs and signing information through several devices or participants. Each signer should verify the destination and fee rather than treat another participant’s signature as proof that the payment is appropriate. Once enough valid signatures are assembled, the transaction can be finalized for broadcast. Collecting a threshold does not itself establish that the network has accepted or confirmed it. Evidence: [Partially Signed Bitcoin Transaction Format](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0174.mediawiki) ## Back up the policy as well as access Recovery can require the output descriptor or spending script and public-key information needed to reconstruct the wallet’s outputs. Keeping two secret keys while losing the policy metadata can make recovery harder. The ability to lose one of three keys is not permission to store the others together carelessly. Correlated loss or compromise can defeat the intended benefit. Evidence: [Output Script Descriptors General Operation](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0380.mediawiki); [Partially Signed Bitcoin Transaction Format](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0174.mediawiki) ## Questions ### Does multisig automatically prevent theft? No. An attacker who obtains enough signing authority, or signers who approve a harmful transaction, can still satisfy the policy. The threshold reduces particular single-key risks only when implemented and operated appropriately. Evidence: [Bitcoin Developer Guide: Transactions](https://developer.bitcoin.org/devguide/transactions.html); [Partially Signed Bitcoin Transaction Format](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0174.mediawiki) ## Claims and scope ### bitcoin-multisig-quick-answer A Bitcoin multisignature arrangement makes a spend require a specified threshold of signatures from an authorized key set. In a two-of-three example, two qualifying keys can authorize the spend. Its resilience depends on how keys, devices, recovery information and decision authority are actually separated. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ### bitcoin-multisig-fact-threshold Threshold: Two-of-three requires two authorized signatures, not all three. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ### bitcoin-multisig-fact-coordination Coordination: A PSBT can carry transaction details between participants before finalization. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ### bitcoin-multisig-fact-backup Backup: The spending script and key information matter as well as private-key backups. Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null} ## Sources - [Bitcoin Developer Guide: Transactions](https://developer.bitcoin.org/devguide/transactions.html) — Bitcoin developer documentation contributors. UTXO inputs, transaction outputs, change and the difference paid as a fee. Locator: P2PKH Script Validation; Transaction Fees And Change. Retrieved: 2026-10-02T17:03:41.190Z. - [Partially Signed Bitcoin Transaction Format](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0174.mediawiki) — Bitcoin BIPs contributors. Exchange of transaction and signing data across participants. Locator: Roles; Creator; Updater; Signer; Finalizer. Retrieved: 2026-10-02T17:22:20.522Z. - [Output Script Descriptors General Operation](https://raw.githubusercontent.com/bitcoin/bips/927b6de9915c9262615a6399de51b200f81e5aa4/bip-0380.mediawiki) — Bitcoin BIPs contributors. Descriptors describe output scripts, keys and derivation information. Locator: Specification; Key expressions; Checksum. Retrieved: 2026-10-02T17:22:20.620Z. ## Revision history - 2026-10-02: Initial Bitcoin encyclopedia entry at this permanent URL. - 2026-10-02: Added reusable claims, explicit source locators, and matching Markdown and JSON. This publishing change does not itself establish factual verification. ## Cite this entry Degrees of Satoshi editorial project. “Bitcoin multisig: what a two-of-three wallet actually requires.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/bitcoin-multisig/