[bitcoindev]

The email from Luke Carriere discusses a draft aimed at standardizing the enforcement policies of co-signers rather than the co-signers themselves. This initiative is highlighted by the need to address compatibility issues between different blockchain security products and services, such as Liquidium and Lendasat, which currently cannot interchange co-signers or oracles due to differing policy implementations.

Luke points out that existing methods, like those using predicates to control signing authority, are already in practice but lack a unified policy format. The proposed draft seeks to establish a standardized format that encompasses various verification methods including open, blinded, and enclave verifications, along with conditions derived both from the transaction itself and external attestations. This would allow for greater interoperability among different blockchain applications and services, adhering to a common set of rules and procedures.

Further, the draft mandates that all script-enforceable conditions must be included in the script and ensures that each policy provides for a spending path independent of co-signer involvement. To facilitate broader use and integration, the draft also stipulates that Discreet Log Contracts (DLC) oracle attestations should be accepted by co-signers without needing adjustments, thus maintaining existing evidence sources.

Luke's request for feedback centers on several unresolved aspects within the draft: the choice between canonical JSON or TLV for policy serialization, the feasibility of specifying blinded verification based on current technologies such as blinded MuSig2, the appropriate placement of statement attestation formats, the adequacy of the output expression language, and the necessity of timelocking fallback paths to prevent early bypassing of co-signers. The draft, available for review, can be accessed at Draft BIP.

In conclusion, this correspondence invites input on whether the drafted policy format is being introduced at the correct structural layer within blockchain technology frameworks and seeks constructive criticism on the draft’s open questions to refine and enhance the proposed standards.