Policy: require minimal push in bare multisig output scripts #35225

pull pinheadmz wants to merge 2 commits into bitcoin:master from pinheadmz:p2ms-nonstandard-nonminimal changing 3 files +56 −13

pinheadmz commented at 7:45 PM on May 6, 2026: member

Closes #23285 by adding CheckMinimalPush() in MatchMultisig() in solver.cpp which is only used for policy checks (not consensus).

First commit asserts current behavior on master with unit and functional tests, second commit tightens the policy.

I noticed CheckMinimalPush() has an assert(0 <= opcode && opcode <= OP_PUSHDATA4). That continues to be protected by GetScriptOp() which has guard if (opcode <= OP_PUSHDATA4)

To address concern about current usage I claude-generated this script which efficiently scanned all blk*.dat files from a fully-synced node and reported all occurrences of this oddity (report below).

Block	Date	vout	Type	Ops	Transaction
244029	2013-06-30	0	1-of-3	OP_PUSHDATA1 ×2	c49b3c445c89d832289de0fd3b0281efdcce418333dacd028061e8de9f0a6f10
244029	2013-06-30	0	1-of-3	OP_PUSHDATA1 ×3	72590fcf0d8021bad77826c5008eaca3541f81d212d55bb7c02ec6a4bf584404
244042	2013-06-30	0	1-of-3	OP_PUSHDATA1 ×2	2d201879608ed2d14c362dff713a6d17d680cb42d5175dfe42e960e94736be04
262733	2013-10-10	3	1-of-2	OP_PUSHDATA1 ×1	055cd2d8ff819ccd7182a08818bf85f79f22e089b81c4f6325014436e172d9b9
263066	2013-10-12	3	1-of-2	OP_PUSHDATA1 ×1	d8773a20a841b4105a98fb2f448f3d9bae2be06f0b9221c02a7cb4d2077f67b9
263069	2013-10-12	2	1-of-2	OP_PUSHDATA1 ×1	5b2169a66a937571767f278097aab307ba95a5dd5beaf9e98a64802218511a52
263096	2013-10-12	2	1-of-2	OP_PUSHDATA1 ×1	c6f2bf13c8742fe5136dba82ce76d1513732d5a5b2d24c8d1bc1a4b92b15cff4
263101	2013-10-12	2	1-of-2	OP_PUSHDATA1 ×1	40af216d3207ba85a47a913a06ace72a10d433ebeb1e12a5c36713a2b11964aa
263421	2013-10-13	2	1-of-3	OP_PUSHDATA1 ×3	11378d2a2bb5514dc7bd5d3bf2eb94dd197e235e9337cac404cf79aa3119e53c
263421	2013-10-13	3	1-of-3	OP_PUSHDATA1 ×3	11378d2a2bb5514dc7bd5d3bf2eb94dd197e235e9337cac404cf79aa3119e53c
263421	2013-10-13	4	1-of-1	OP_PUSHDATA1 ×1	11378d2a2bb5514dc7bd5d3bf2eb94dd197e235e9337cac404cf79aa3119e53c
264469	2013-10-18	1	1-of-3	OP_PUSHDATA1 ×3	92a9a88b078d69de943d9d5d1d3e6b51652952200578e655e50cafaf45a17c34
264469	2013-10-18	2	1-of-3	OP_PUSHDATA1 ×2	92a9a88b078d69de943d9d5d1d3e6b51652952200578e655e50cafaf45a17c34
264469	2013-10-18	1	1-of-3	OP_PUSHDATA1 ×3	7c0eec816b67145a67cbfd479e3c3474df814e31c2e6ff752a48a5a6754c6c2c
264469	2013-10-18	2	1-of-3	OP_PUSHDATA1 ×2	7c0eec816b67145a67cbfd479e3c3474df814e31c2e6ff752a48a5a6754c6c2c
268068	2013-11-05	0	1-of-2	OP_PUSHDATA1 ×1	8e2c7cec5006949e1929f70961da8f85eebfe06a4979d611ec93ab384eaa34ed
268068	2013-11-05	0	1-of-2	OP_PUSHDATA1 ×1	5e29ff050333e2d01a1995cee2ec81f7549baeaef56aa38cb912184794837e84
337908	2015-01-07	2	1-of-1	OP_PUSHDATA1 ×1	04ab6edee514a0ee2aeff48ca672d6f47d6c40923abb0d78aa33ec7e2001eb09

test: assert current policy allows bare multisig with nonminimal push 25b4841588
POLICY: require bare multisig outputs use minimal push for pubkeys 36462c7a31
DrahtBot added the label TX fees and policy on May 6, 2026
DrahtBot commented at 7:45 PM on May 6, 2026: contributor



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#23285 Missing CheckMinimalPush check in MatchMultisig: largest IsStandard multisig n-of-3 is 12 bytes too large?

Policy: require minimal push in bare multisig output scripts #35225

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