Simplifying the Signature Generation Schema for Nakamoto Activation
July 23, 2024
As we approach Nakamoto Activation, Signers have been steadily preparing and collaborating with Core Developers. This post will summarize SIP-025, an addendum to the previously approved SIP-021 representing a proposal to temporarily simplify the threshold signature scheme for Signers. The SIP is authored by core developers and leaders from the Stacks Signer network and will be voting on by Signers in the coming weeks.
What is SIP-025?
SIP-025 is a "rider" SIP, meaning it serves as an addendum to the previously accepted SIP-021. SIP-021 covers the significant architectural shift to the Stacks blockchain, aiming to enhance block production speed and reliability, otherwise known as Nakamoto. SIP-025 proposes a short-term change to one specific aspect: the signature generation schema.
The Need for SIP-025
The previously approved SIP-021 proposes a sophisticated Weighted Schnorr Threshold Signatures (WSTS) system for block validation, which ensures robust security and efficiency. While WSTS is essential for the long-term functionality of the Stacks blockchain, it is not required until future progressions of sBTC are released. To further reduce complexity in an already complex Nakamoto release, SIP-025 suggests a temporary first iterative step towards the full WSTS signature schema vs implementation of the full scheme.
Under SIP-025, the signature generation will adopt a simpler concatenation method similar to Bitcoin's P2SH multisig. This means each Stacker will append their signature individually rather than aggregating them via WSTS. Although this approach is less efficient, it is simpler and faster to implement, facilitating the Nakamoto Activation step. You can read the full draft of SIP-025 here.
Under SIP-025, the signature generation will adopt a simpler concatenation method similar to Bitcoin's P2SH multisig. This means each Stacker will append their signature individually rather than aggregating them via WSTS. Although this approach is less efficient, it is simpler and faster to implement, facilitating the Nakamoto Activation step. You can read the full draft of SIP-025 here.
Timeline and Future Transition
The simplification proposed by SIP-025 is temporary. After Nakamoto reaches Activation (Stacks 3.0), the plan is to transition to the originally proposed WSTS system shortly after, in a release numbered Stacks 3.1. This phased approach allows core developers to simplify the immediate release and align work most relevant to sBTC, to a release more aligned with sBTC, without compromising on the long-term benefits of a more advanced signature system.
Next Steps
We encourage all community members to review the details of SIP-025. As a Rider SIP proposing a tweak to implementation details there will not be a community vote, however, Signers will be asked to signal their support or rejection of the change starting around July 30th, 2024. Signers will essentially issue a special kind of transaction we’ll be able to see on the network, results of this vote will be aggregated and shared when the vote finishes at the end of Cycle 90. This vote is timed to complete at the same time at as the community votes on SIP-027 - learn more about this vote via the link below.