Mastering Blockchain - Second Edition

Commonly used opcodes

All opcodes are declared in the script.h file in the Bitcoin reference client source code.

This can be accessed from the link at https://github.com/bitcoin/bitcoin/blob/master/src/script/script.h under the following comment: /** Script opcodes */

A description of the most commonly used opcodes is listed here. This table is taken from the Bitcoin developer's guide:

Opcode	Description
OP_CHECKSIG	This takes a public key and signature and validates the signature of the hash of the transaction. If it matches, then TRUE is pushed onto the stack; otherwise, FALSE is pushed.
OP_EQUAL	This returns 1 if the inputs are exactly equal; otherwise, 0 is returned.
OP_DUP	This duplicates the top item in the stack. ...