CHECKSIG

Word: OP_CHECKSIG
Opcode: 172
Hex: 0xac

CHECKSIG: The entire transaction's outputs, inputs, and script (from the most recently-executed OPCODESEPARATOR to the end) are hashed. The signature used by OPCHECKSIG must be a valid signature for this hash and public key. If it is, 1 is returned, 0 otherwise.