OPCAT (opcat)

We propose a novel UTXO-based token protocol on Bitcoin, called Covenant Attested Token (CAT) Protocol. It is miner validated and uses smart contracts, specifically covenants, to manage token mints and transfers. Compared with all existing token protocols on Bitcoin, it is solely enforced by Bitcoin Script at Layer 1 and has the following features. CAT protocol supports both fungible tokens (called CAT20 standard) and non-fungible tokens (called CAT721 standard). The techniques developed here are general purpose and can be applied in use cases beyond tokens.