[bitcoindev]

Currently, platforms such as Liquidium and Lendasat face challenges due to incompatible policy implementations, which hinder the interchangeability of co-signers and oracles. While predicate-based mechanisms are already used to control signing authority, these methods vary widely and lack a unified format. Introducing a standardized approach aims to bridge this gap by establishing a common policy structure that can accommodate diverse verification techniques—including open, blinded, and enclave verifications—along with conditions derived from both on-chain transactions and external attestations.

The proposed draft outlines requirements for comprehensive policy expression, mandating that all script-enforceable conditions be included directly within the controlling scripts. Additionally, it ensures that every policy provides a spending path independent of co-signer participation, thereby enhancing system resilience and flexibility. To further promote compatibility and adoption, Discreet Log Contracts (DLC) oracle attestations are accepted without the need for modification, preserving existing evidence sources and minimizing friction during integration. The draft serves as a foundation for cross-platform interaction, encouraging blockchain applications and services to adhere to a shared set of rules and procedures.

Several technical considerations remain under active discussion. The draft invites feedback on issues such as the choice between canonical JSON or TLV for policy serialization, the practicality of specifying blinded verification based on technologies like blinded MuSig2, and the optimal organization of statement attestation formats. Additional areas requiring input include the sufficiency of the output expression language and the implementation of timelocked fallback paths to ensure co-signers cannot be bypassed prematurely. The inclusion of reference materials, such as the Draft BIP, facilitates transparent review and encourages collaborative refinement.

Recent updates to the draft, including version 2.1 (commit details), address key points such as fail-closed policy validation, explicit fields, version-first commitments, signed statement finality, and corrected safety conditions. Despite these advancements, unresolved topics persist, particularly concerning the complete wire schema, the selection of serialization methods, and a definitive reference implementation. Open channels for discussion remain available on Delving Bitcoin, inviting further critique and contributions from the community to enhance and finalize the proposed standards.