Encyclopedia How the network works · Entry 85
Bitcoin multisig: what a two-of-three wallet actually requires
In this article
At a glance
Key facts
| Fact | Detail | Source |
|---|---|---|
| Threshold | Two-of-three requires two authorized signatures, not all three. | [1] |
| Coordination | A PSBT can carry transaction details between participants before finalization. | [2] |
| Backup | The spending script and key information matter as well as private-key backups. | [3][2] |
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.
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.
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.
Direct answers
Questions people ask
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.
Inspect the evidence
The answer and key facts have stable claim links. These records retain the scope and qualification when reused.
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: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimThreshold: Two-of-three requires two authorized signatures, not all three.
Scope: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimCoordination: A PSBT can carry transaction details between participants before finalization.
Scope: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimBackup: The spending script and key information matter as well as private-key backups.
Scope: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimRevision history
- — Initial Bitcoin encyclopedia entry at this permanent URL.
- — Added reusable claims, explicit source locators, and matching Markdown and JSON. This publishing change does not itself establish factual verification.
Source register
Sources and references
Retrieval dates and locators are recorded individually.- Bitcoin Developer Guide: TransactionsBitcoin developer documentation contributors
UTXO inputs, transaction outputs, change and the difference paid as a fee.
Locator: P2PKH Script Validation; Transaction Fees And Change · Retrieved: 2026-10-02T17:03:41.190ZOpen source - Partially Signed Bitcoin Transaction FormatBitcoin BIPs contributors
Exchange of transaction and signing data across participants.
Locator: Roles; Creator; Updater; Signer; Finalizer · Version / scope: BIP-174; immutable revision pinned in source URL · Retrieved: 2026-10-02T17:22:20.522ZOpen source - Output Script Descriptors General OperationBitcoin BIPs contributors
Descriptors describe output scripts, keys and derivation information.
Locator: Specification; Key expressions; Checksum · Version / scope: BIP-380; immutable revision pinned in source URL · Retrieved: 2026-10-02T17:22:20.620ZOpen source
Research and drafting use AI assistance. A separate automated review checks claims against primary sources; no external expert or named human review is implied. Publication, substantive editing, source retrieval and verification are recorded separately. This version was independently checked by an automated reviewer on 2 October 2026.
Editorial method and correctionsDegrees 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/