Hello bitcoin-devs,

Below is a link to a BIP Draft for a new opcode, OP_CHECKOUTPUTSHASHVERIFY. This opcode enables an easy-to-use trustless congestion control techniques via a rudimentary, limited form of covenant which does not bear the same technical and social risks of prior covenant designs.

Congestion control allows Bitcoin users to confirm payments to many users in a single transaction without creating the UTXO on-chain until a later time. This therefore improves the throughput of confirmed payments, at the expense of latency on spendability and increased average block space utilization. The BIP covers this use case in detail, and a few other use cases lightly.

The BIP draft is here:

https://github.com/JeremyRubin/bips/blob/op-checkoutputshashverify/bip-coshv.mediawiki

The BIP proposes to deploy the change simultaneously with Taproot as an OPSUCCESS, but it could be deployed separately if needed.

An initial reference implementation of the consensus changes and tests which demonstrate how to use it for basic congestion control is available at https://github.com/JeremyRubin/bitcoin/tree/congestion-control. The changes are about 74 lines of code on top of sipa's Taproot reference implementation.

Best regards,

Jeremy Rubin