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diff --git a/README.mediawiki b/README.mediawiki index 1d8164a..c6a275e 100644 --- a/README.mediawiki +++ b/README.mediawiki @@ -1071,6 +1071,13 @@ Those proposing changes should consider that ultimately consent may rest with th | Pieter Wuille, Andrew Chow | Informational | Draft +|- +| [[bip-0383.mediawiki|383]] +| Applications +| Multisig Output Script Descriptors +| Pieter Wuille, Andrew Chow +| Informational +| Draft |} <!-- IMPORTANT! See the instructions at the top of this page, do NOT JUST add BIPs here! --> diff --git a/bip-0380.mediawiki b/bip-0380.mediawiki index e48afe0..76fb721 100644 --- a/bip-0380.mediawiki +++ b/bip-0380.mediawiki @@ -252,4 +252,10 @@ This Table lists all available Script expressions and the BIPs specifying them. |- | <tt>wsh(SCRIPT)</tt> | [[bip-0382.mediawiki|382]] +|- +| <tt>multi(NUM, KEY, ..., KEY)</tt> +| [[bip-0383.mediawiki|383]] +|- +| <tt>sortedmulti(NUM, KEY, ..., KEY)</tt> +| [[bip-0383.mediawiki|383]] |} diff --git a/bip-0383.mediawiki b/bip-0383.mediawiki new file mode 100644 index 0000000..6b74950 --- /dev/null +++ b/bip-0383.mediawiki @@ -0,0 +1,78 @@ +<pre> + BIP: 383 + Layer: Applications + Title: Multisig Output Script Descriptors + Author: Pieter Wuille <pieter@wuille.net> + Andrew Chow <andrew@achow101.com> + Comments-Summary: No comments yet. + Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0383 + Status: Draft + Type: Informational + Created: 2021-06-27 + License: BSD-2-Clause +</pre> + +==Abstract== + +This document specifies <tt>multi()</tt>, and <tt>sortedmulti()</tt> output script descriptors. +Both functions take a threshold and one or more public keys and produce a multisig output script. +<tt>multi()</tt> specifies the public keys in the output script in the order given in the descriptor while <tt>sortedmulti()</tt> sorts the public keys lexicographically when the output script is produced. + +==Copyright== + +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: <tt>multi()</tt>, and <tt>sortedmulti()</tt>. +Both expressions produce the scripts of the same template and take the same arguments. +They are written as <tt>multi(k,KEY_1,KEY_2,...,KEY_n)</tt>. +<tt>k</tt> is the threshold - the number of keys that must sign the input for the script to be valid. +<tt>KEY_1,KEY_2,...,KEY_n</tt> are the key expressions for the multisig. <tt>k</tt> must be less than or equal to <tt>n</tt>. + +<tt>multi()</tt> and <tt>sortedmulti()</tt> expressions can be used as a top level expression, or inside of either a <tt>sh()</tt> or <tt>wsh()</tt> 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 <tt>n</tt>. +When used at the top level, there can only be at most 3 keys. +When used inside of a <tt>sh()</tt> expression, there can only be most 15 compressed public keys (this is limited by the P2SH script limit). +Otherwise the maximum number of keys is 20. + +The output script produced also depends on the value of <tt>k</tt>. If <tt>k</tt> is less than or equal to 16: +<pre> +OP_k KEY_1 KEY_2 ... KEY_n OP_CHECKMULTISIG +</pre> + +if <tt>k</tt> is greater than 16: +<pre> +k KEY_1 KEY_2 ... KEY_n OP_CHECKMULTISIG +</pre> + +===<tt>sortedmulti()</tt>=== + +The only change for <tt>sortedmulti()</tt> 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</tt>=== + +When one or more the key expressions in a <tt>multi()</tt> or <tt>sortedmulti()</tt> 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== + +TBD + +==Backwards Compatibility== + +<tt>multi()</tt>, and <tt>sortedmulti()</tt> descriptors use the format and general operation specified in [[bip-0380.mediawiki|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 Implemntation== + +<tt>multi()</tt>, and <tt>multi()</tt> descriptors have been implemented in Bitcoin Core since version 0.17. |