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OP_CHECKMULTISIGVERIFY ​

INFO

Opcode number: 175
Byte representation: 0xaf
Short description: Verify multiple signatures and fail the script if the verification fails.

OP_CHECKMULTISIGVERIFY combines OP_CHECKMULTISIG and OP_VERIFY. It checks whether a set of signatures are valid for a set of public keys and fails the script immediately if the verification fails. Unlike OP_CHECKMULTISIG, it does not push a result to the stack; it either passes silently or causes script failure.

Operation ​

  1. Pops an integer n: total number of public keys.
  2. Pops n public keys.
  3. Pops an integer m: number of required signatures.
  4. Pops m signatures.
  5. Pops one extra unused value (typically OP_0 — see bug note below).
  6. Verifies that at least m signatures are valid for the public keys.
  7. If valid: continue script execution.
  8. If invalid: script fails immediately.

Notes ​

  • Functionally equivalent to OP_CHECKMULTISIG OP_VERIFY, but more compact.
  • The dummy OP_0 is still required due to the historical off-by-one bug in OP_CHECKMULTISIG. See the OP_CHECKMULTISIG page for details of this bug.
  • Used in scripts where the multisig check must pass for the script to continue—ideal when no result is needed on the stack.
  • Used in P2SH scripts that chain multiple verification steps.
  • Special quirk: The dummy value. As with OP_CHECKMULTISIG, you must include a dummy element (OP_0) before the signatures. This accounts for a bug in the original implementation that incorrectly counted elements during verification. Even though it has no effect, omitting it will break the script.

Examples ​

Example 1

2-of-3 multisig, verification required.

shell
# ASM script
OP_2 <pubkey1> <pubkey2> <pubkey3> OP_3 OP_CHECKMULTISIGVERIFY

# Raw script (simplified)
00 <sig1> <sig2> 52 <pk1> <pk2> <pk3> 53 ae

# Stack (after OP_CHECKMULTISIGVERIFY)
(empty) — continues execution if valid