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BIP 383: Multisig Output Script Descriptors

Also known as: multisig descriptors, multi(), sortedmulti(), BIP383, BIP-0383.

In plain English: Defines descriptor functions for multisignature setups, where a certain number of keys out of a group must sign. One version keeps keys in the given order and another sorts them automatically, which helps different wallets reproduce identical multisig addresses.

Status
Deployed
Type
Specification
Layer
Applications
Authors
Pieter Wuille, Ava Chow
Assigned
Last changed
Requires
BIP 380
Topics
Wallets
Source
bip-0383.mediawiki on GitHub · Markdown

Full specification

Abstract

This document specifies multi(), and sortedmulti() output script descriptors. Both functions take a threshold and one or more public keys and produce a multisig output script. multi() specifies the public keys in the output script in the order given in the descriptor while sortedmulti() sorts the public keys lexicographically when the output script is produced.

This BIP is licensed under the BSD 2-clause license.

Motivation

The most common complex script used in Bitcoin is a threshold multisig. These expressions allow specifying multisig scripts as a descriptor.

Specification

Two new script expressions are defined: multi(), and sortedmulti(). Both expressions produce the scripts of the same template and take the same arguments. They are written as multi(k,KEY_1,KEY_2,...,KEY_n). k is the threshold - the number of keys that must sign the input for the script to be valid. KEY_1,KEY_2,...,KEY_n are the key expressions for the multisig. k must be less than or equal to n.

multi() and sortedmulti() expressions can be used as a top level expression, or inside of either a sh() or wsh() descriptor. Depending on the higher level descriptors, there may be restrictions on the type of public keys that can be included.

Depending on the higher level descriptors, there are also restrictions on the number of keys that can be present, i.e. the maximum value of n. When used at the top level, there can only be at most 3 keys. When used inside of a sh() expression, the output script produced is the redeem script, which is pushed as a single element in the spending scriptSig and must therefore not exceed the 520 byte limit on the size of a script element. This allows at most 15 compressed public keys, or at most 7 uncompressed ones, as an uncompressed key takes 66 bytes of the script rather than 34. Otherwise the maximum number of keys is 20.

The output script produced will be

k KEY_1 KEY_2 ... KEY_n n OP_CHECKMULTISIG

The values k and n must be minimally encoded integers. For values less than or equal to 16, they must be encoded using OP_0 through OP_16. For values greater than 16, they must be a push of the signed little endian encoded value without padding.

sortedmulti()

The only change for sortedmulti() is that the keys are sorted lexicographically prior to the creation of the output script. This sorting is on the keys that are to be put into the output script, i.e. after all extended keys are derived.

Multiple Extended Keys

When one or more the key expressions in a multi() or sortedmulti() expression are extended keys, the derived keys use the same child index. This changes the keys in lockstep and allows for output scripts to be indexed in the same way that the derived keys are indexed.

Test Vectors

Valid descriptors followed by the scripts they produce. Descriptors involving derived child keys will have the 0th, 1st, and 2nd scripts listed.

  • multi(1,L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1,5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)
    • 512103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd4104a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea23552ae
  • multi(1,03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd,04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)
    • 512103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd4104a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea23552ae
  • sortedmulti(1,04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235,03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)
    • 512103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd4104a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea23552ae
  • sh(multi(2,[00000000/111'/222]xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/0))
    • a91445a9a622a8b0a1269944be477640eedc447bbd8487
  • sortedmulti(2,xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL/*,xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y/0/0/*)
    • 5221025d5fc65ebb8d44a5274b53bac21ff8307fec2334a32df05553459f8b1f7fe1b62102fbd47cc8034098f0e6a94c6aeee8528abf0a2153a5d8e46d325b7284c046784652ae
    • 52210264fd4d1f5dea8ded94c61e9641309349b62f27fbffe807291f664e286bfbe6472103f4ece6dfccfa37b211eb3d0af4d0c61dba9ef698622dc17eecdf764beeb005a652ae
    • 5221022ccabda84c30bad578b13c89eb3b9544ce149787e5b538175b1d1ba259cbb83321024d902e1a2fc7a8755ab5b694c575fce742c48d9ff192e63df5193e4c7afe1f9c52ae
  • wsh(multi(2,xprv9s21ZrQH143K31xYSDQpPDxsXRTUcvj2iNHm5NUtrGiGG5e2DtALGdso3pGz6ssrdK4PFmM8NSpSBHNqPqm55Qn3LqFtT2emdEXVYsCzC2U/2147483647'/0,xprv9vHkqa6EV4sPZHYqZznhT2NPtPCjKuDKGY38FBWLvgaDx45zo9WQRUT3dKYnjwih2yJD9mkrocEZXo1ex8G81dwSM1fwqWpWkeS3v86pgKt/1/2/*,xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi/10/20/30/40/*'))
    • 0020b92623201f3bb7c3771d45b2ad1d0351ea8fbf8cfe0a0e570264e1075fa1948f
    • 002036a08bbe4923af41cf4316817c93b8d37e2f635dd25cfff06bd50df6ae7ea203
    • 0020a96e7ab4607ca6b261bfe3245ffda9c746b28d3f59e83d34820ec0e2b36c139c
  • sh(wsh(multi(16,03669b8afcec803a0d323e9a17f3ea8e68e8abe5a278020a929adbec52421adbd0,0260b2003c386519fc9eadf2b5cf124dd8eea4c4e68d5e154050a9346ea98ce600,0362a74e399c39ed5593852a30147f2959b56bb827dfa3e60e464b02ccf87dc5e8,0261345b53de74a4d721ef877c255429961b7e43714171ac06168d7e08c542a8b8,02da72e8b46901a65d4374fe6315538d8f368557dda3a1dcf9ea903f3afe7314c8,0318c82dd0b53fd3a932d16e0ba9e278fcc937c582d5781be626ff16e201f72286,0297ccef1ef99f9d73dec9ad37476ddb232f1238aff877af19e72ba04493361009,02e502cfd5c3f972fe9a3e2a18827820638f96b6f347e54d63deb839011fd5765d,03e687710f0e3ebe81c1037074da939d409c0025f17eb86adb9427d28f0f7ae0e9,02c04d3a5274952acdbc76987f3184b346a483d43be40874624b29e3692c1df5af,02ed06e0f418b5b43a7ec01d1d7d27290fa15f75771cb69b642a51471c29c84acd,036d46073cbb9ffee90473f3da429abc8de7f8751199da44485682a989a4bebb24,02f5d1ff7c9029a80a4e36b9a5497027ef7f3e73384a4a94fbfe7c4e9164eec8bc,02e41deffd1b7cce11cde209a781adcffdabd1b91c0ba0375857a2bfd9302419f3,02d76625f7956a7fc505ab02556c23ee72d832f1bac391bcd2d3abce5710a13d06,0399eb0a5487515802dc14544cf10b3666623762fbed2ec38a3975716e2c29c232)))
    • a9147fc63e13dc25e8a95a3cee3d9a714ac3afd96f1e87
  • wsh(multi(20,KzoAz5CanayRKex3fSLQ2BwJpN7U52gZvxMyk78nDMHuqrUxuSJy,KwGNz6YCCQtYvFzMtrC6D3tKTKdBBboMrLTsjr2NYVBwapCkn7Mr,KxogYhiNfwxuswvXV66eFyKcCpm7dZ7TqHVqujHAVUjJxyivxQ9X,L2BUNduTSyZwZjwNHynQTF14mv2uz2NRq5n5sYWTb4FkkmqgEE9f,L1okJGHGn1kFjdXHKxXjwVVtmCMR2JA5QsbKCSpSb7ReQjezKeoD,KxDCNSST75HFPaW5QKpzHtAyaCQC7p9Vo3FYfi2u4dXD1vgMiboK,L5edQjFtnkcf5UWURn6UuuoFrabgDQUHdheKCziwN42aLwS3KizU,KzF8UWFcEC7BYTq8Go1xVimMkDmyNYVmXV5PV7RuDicvAocoPB8i,L3nHUboKG2w4VSJ5jYZ5CBM97oeK6YuKvfZxrefdShECcjEYKMWZ,KyjHo36dWkYhimKmVVmQTq3gERv3pnqA4xFCpvUgbGDJad7eS8WE,KwsfyHKRUTZPQtysN7M3tZ4GXTnuov5XRgjdF2XCG8faAPmFruRF,KzCUbGhN9LJhdeFfL9zQgTJMjqxdBKEekRGZX24hXdgCNCijkkap,KzgpMBwwsDLwkaC5UrmBgCYaBD2WgZ7PBoGYXR8KT7gCA9UTN5a3,KyBXTPy4T7YG4q9tcAM3LkvfRpD1ybHMvcJ2ehaWXaSqeGUxEdkP,KzJDe9iwJRPtKP2F2AoN6zBgzS7uiuAwhWCfGdNeYJ3PC1HNJ8M8,L1xbHrxynrqLKkoYc4qtoQPx6uy5qYXR5ZDYVYBSRmCV5piU3JG9,KzRedjSwMggebB3VufhbzpYJnvHfHe9kPJSjCU5QpJdAW3NSZxYS,Kyjtp5858xL7JfeV4PNRCKy2t6XvgqNNepArGY9F9F1SSPqNEMs3,L2D4RLHPiHBidkHS8ftx11jJk1hGFELvxh8LoxNQheaGT58dKenW,KyLPZdwY4td98bKkXqEXTEBX3vwEYTQo1yyLjX2jKXA63GBpmSjv))
    • 0020376bd8344b8b6ebe504ff85ef743eaa1aa9272178223bcb6887e9378efb341ac
  • sh(wsh(multi(20,KzoAz5CanayRKex3fSLQ2BwJpN7U52gZvxMyk78nDMHuqrUxuSJy,KwGNz6YCCQtYvFzMtrC6D3tKTKdBBboMrLTsjr2NYVBwapCkn7Mr,KxogYhiNfwxuswvXV66eFyKcCpm7dZ7TqHVqujHAVUjJxyivxQ9X,L2BUNduTSyZwZjwNHynQTF14mv2uz2NRq5n5sYWTb4FkkmqgEE9f,L1okJGHGn1kFjdXHKxXjwVVtmCMR2JA5QsbKCSpSb7ReQjezKeoD,KxDCNSST75HFPaW5QKpzHtAyaCQC7p9Vo3FYfi2u4dXD1vgMiboK,L5edQjFtnkcf5UWURn6UuuoFrabgDQUHdheKCziwN42aLwS3KizU,KzF8UWFcEC7BYTq8Go1xVimMkDmyNYVmXV5PV7RuDicvAocoPB8i,L3nHUboKG2w4VSJ5jYZ5CBM97oeK6YuKvfZxrefdShECcjEYKMWZ,KyjHo36dWkYhimKmVVmQTq3gERv3pnqA4xFCpvUgbGDJad7eS8WE,KwsfyHKRUTZPQtysN7M3tZ4GXTnuov5XRgjdF2XCG8faAPmFruRF,KzCUbGhN9LJhdeFfL9zQgTJMjqxdBKEekRGZX24hXdgCNCijkkap,KzgpMBwwsDLwkaC5UrmBgCYaBD2WgZ7PBoGYXR8KT7gCA9UTN5a3,KyBXTPy4T7YG4q9tcAM3LkvfRpD1ybHMvcJ2ehaWXaSqeGUxEdkP,KzJDe9iwJRPtKP2F2AoN6zBgzS7uiuAwhWCfGdNeYJ3PC1HNJ8M8,L1xbHrxynrqLKkoYc4qtoQPx6uy5qYXR5ZDYVYBSRmCV5piU3JG9,KzRedjSwMggebB3VufhbzpYJnvHfHe9kPJSjCU5QpJdAW3NSZxYS,Kyjtp5858xL7JfeV4PNRCKy2t6XvgqNNepArGY9F9F1SSPqNEMs3,L2D4RLHPiHBidkHS8ftx11jJk1hGFELvxh8LoxNQheaGT58dKenW,KyLPZdwY4td98bKkXqEXTEBX3vwEYTQo1yyLjX2jKXA63GBpmSjv)))
    • a914c2c9c510e9d7f92fd6131e94803a8d34a8ef675e87

Invalid descriptors

  • More than 15 keys in P2SH multisig: sh(multi(16,03669b8afcec803a0d323e9a17f3ea8e68e8abe5a278020a929adbec52421adbd0,0260b2003c386519fc9eadf2b5cf124dd8eea4c4e68d5e154050a9346ea98ce600,0362a74e399c39ed5593852a30147f2959b56bb827dfa3e60e464b02ccf87dc5e8,0261345b53de74a4d721ef877c255429961b7e43714171ac06168d7e08c542a8b8,02da72e8b46901a65d4374fe6315538d8f368557dda3a1dcf9ea903f3afe7314c8,0318c82dd0b53fd3a932d16e0ba9e278fcc937c582d5781be626ff16e201f72286,0297ccef1ef99f9d73dec9ad37476ddb232f1238aff877af19e72ba04493361009,02e502cfd5c3f972fe9a3e2a18827820638f96b6f347e54d63deb839011fd5765d,03e687710f0e3ebe81c1037074da939d409c0025f17eb86adb9427d28f0f7ae0e9,02c04d3a5274952acdbc76987f3184b346a483d43be40874624b29e3692c1df5af,02ed06e0f418b5b43a7ec01d1d7d27290fa15f75771cb69b642a51471c29c84acd,036d46073cbb9ffee90473f3da429abc8de7f8751199da44485682a989a4bebb24,02f5d1ff7c9029a80a4e36b9a5497027ef7f3e73384a4a94fbfe7c4e9164eec8bc,02e41deffd1b7cce11cde209a781adcffdabd1b91c0ba0375857a2bfd9302419f3,02d76625f7956a7fc505ab02556c23ee72d832f1bac391bcd2d3abce5710a13d06,0399eb0a5487515802dc14544cf10b3666623762fbed2ec38a3975716e2c29c232))
  • Invalid threshold: multi(a,03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd,04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)
  • Threshold of 0: multi(0,03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd,04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)
  • Threshold larger than keys: multi(3,L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1,5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss)

Backwards Compatibility

multi(), and sortedmulti() descriptors use the format and general operation specified in 380. As these are a wholly new descriptors, they are not compatible with any implementation. However the scripts produced are standard scripts so existing software are likely to be familiar with them.

Reference Implementation

multi(), and sortedmulti() descriptors have been implemented in Bitcoin Core since version 0.17.

Questions about BIP 383

What is BIP 383?

BIP 383, “Multisig Output Script Descriptors”, is a specification Bitcoin Improvement Proposal written by Pieter Wuille and Ava Chow and assigned in June 2021. Defines descriptor functions for multisignature setups, where a certain number of keys out of a group must sign. One version keeps keys in the given order and another sorts them automatically, which helps different wallets reproduce identical multisig addresses.

Is BIP 383 active?

Yes. BIP 383 has the status Deployed, which means it is live: adopted by the Bitcoin network or by widely used software.

Who wrote BIP 383?

BIP 383 was written by Pieter Wuille and Ava Chow. Its number was assigned on June 27, 2021.

What does BIP 383 build on?

BIP 383 requires BIP 380 (Output Script Descriptors General Operation). Read it first to understand this proposal.

Which BIPs build on BIP 383?

2 other BIPs reference BIP 383: BIP 380 (Output Script Descriptors General Operation) and BIP 129 (Bitcoin Secure Multisig Setup (BSMS)).

Where can I read the full BIP 383 specification?

The complete text of BIP 383 is on this page, taken unchanged from the official bitcoin/bips repository on GitHub. It is also available as Markdown and JSON.

BIPs that build on BIP 383

  • BIP 380: Output Script Descriptors General Operation: Deployed. Output script descriptors are a compact text language for describing exactly which addresses a wallet owns and how they are spent. This document defines their general syntax and checksum, giving…
  • BIP 129: Bitcoin Secure Multisig Setup (BSMS): Complete. Defines a step-by-step procedure for securely setting up a multisignature wallet, where several devices or people must approve spending. It helps participants verify each other's keys and confirm…

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