Bitcoin Covenants Part 4: OP_CHECKSIGFROMSTACK and OP_CAT
CoinTelegraph·July 13, 2026·1 min read
OP_CSFS authenticates signatures over arbitrary data. OP_CAT concatenates stack values into a single message. Together, they let Bitcoin scripts verify transaction structure at spend time, without pre-signed key management or new consensus rules beyond the two opcodes themselves.
