Protocol & Consensus • Estimated 20m

OP_CHECKMULTISIG

protocol.op-checkmultisig

Legacy Script opcode that verifies an m-of-n set of signatures against a list of public keys. Its historical off-by-one bug explains why multisig spends include a leading OP_0 placeholder in the unlocking script.

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Curated resources (3)

• P2MS - Pay To Multisig (article) Decoding walkthrough showing how OP_CHECKMULTISIG appears in bare multisig locking scripts and why OP_0 is required when spending them.
• Bitcoin Developer Guide: Transactions (article) Canonical description of multisig scripts, the extra stack item bug, and the standard script form used with OP_CHECKMULTISIG.
• Programming Bitcoin (book) Script-level reference for opcode behavior, stack evaluation, and legacy multisig spending patterns.

Direct prerequisites (1)

• Bitcoin Script

Direct dependents (1)

• Pay-to-Multisig (P2MS)

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