BIP Proposal: Stateless PSBT Coordination (Blind Relay)

This innovative approach employs an ephemeral, end-to-end encrypted WebSocket architecture that enhances security and privacy by ensuring the relay server cannot access the PSBTs, extended public keys, or signatures, thereby maintaining a zero-knowledge operational state. All data related to the transaction room is automatically deleted either when the room is closed or after 24 hours, addressing concerns about data persistence and potential privacy leaks. Operational security is further reinforced as the URL of the room and decryption key must be shared out-of-band, enhancing user control and security. The community is invited to review and provide feedback on this protocol through the draft BIP available here.

The release of Signing Room version 2.0.0 marks significant enhancements in its functionality and user experience, particularly with the introduction of a drop-in web component that allows easy integration using a single HTML tag. This feature simplifies the developer's work significantly and aims to make the Signing Room software more accessible across various platforms. Detailed documentation on these updates is available on GitHub, which provides an exhaustive overview of all modifications and improvements in this release, accessible here.

Further development in the realm of PSBT coordination is evidenced by the launch of @signing-room/sdk version 1.0.0. This new TypeScript SDK, decoupled from the main Angular client, is framework-agnostic, enabling developers to manage end-to-end encrypted PSBT coordination ceremonies programmatically. It supports real-time synchronization of actions like room creation, participant joining, and signature uploads across the system. The SDK also promises new possibilities such as headless multisig automation where AI agents can autonomously perform signing ceremonies under human supervision. A comprehensive developer walkthrough is available, detailing the setup and use of the SDK, along with resources hosted on GitHub and NPM. A video tutorial can also be found on YouTube, providing practical insights into the implementation and capabilities of the SDK.

An update on recent developments includes the release of versions 3.4.0 of the coordinator and 1.2.0 of the SDK, focusing on introducing Role-Based Access Control (RBAC) without accounts or database states, thus preserving the anonymity of participants. This enhancement caters especially to scenarios requiring a high level of security and compliance, such as institutional or legal environments. The updates include role-scoped capability tokens for different participant roles, enforced ephemerally to prevent unauthorized actions within the transaction process. Further details and specifications can be explored through the release notes and the updated BIP draft, which includes revised URL fragment schema and capability token message formats available here. The ongoing work aims to expand support to Tapscript / BIP 371 to accommodate more complex transaction types like Miniscript spending trees. Feedback on these developments is highly valued to refine and enhance the functionalities further.