Blockstream a blockchain technology startup, announced the release of Musig, a test code for the proposed Schnorr-based multi-signature scheme on February 18. The MuSig scheme is a Bitcoin upgrade implementation that is focused on scalability and confidential transactions.
According to Andrew Poelstra, the company’s mathematician, this latest release is the turning point in the development of the Schnorr multi-signatures concept.
According to the announcement post:
“MuSig is a protocol that allows a group of signers to produce a short, joint signature on a common message.” The concept was introduced last year by Poelstra and other software engineers and since then they have worked hard to turn this concept into reality.
“We’ve been turning MuSig from an academic paper into a usable code, and this week we merged that code into secp256k1-zkp, a fork of secp256k1, the high-assurance cryptographic library used by Bitcoin Core.”
Old Issues Solved
While Bitcoin use-cases are growing, there is a need to streamline the signature scheme. This was the main reason leading to the development of the MuSig Signature algorithm.
Presently, bitcoin implements a digital signature algorithm is called ECDSA. However, this algorithm has some limitations since “multisignatures and threshold signatures – signatures made by a quorum of independent parties rather than a single person – are very difficult to produce with ECDSA.” making it unfeasible as a functional algorithm for multisignature usability. T
his works as an imposition, forcing developers to “use Bitcoin Script for applications such as cross-chain atomic swaps or Lightning”.
“To address these concerns, we started an initiative to design a new signature scheme, and a significant practical engineering effort to implement it in a robust and ant fragile way.”
Implementing Musig on the Bitcoin upgrade
By having developed a more robust algorithm for multi-signing, Blockstream is looking to implement its new release into the Bitcoin firmware.
“As the bitcoin community is exploring the use of Schnorr signatures in bitcoin we hope that our code will eventually be merged into the upstream library secp256k1 used by bitcoin core and many other projects.”
While multi-party protocols present more complex and hard challenges than single-party protocols, Blockstream was able to design an algorithm that is capable of being much more simple and easy to use.
For now, the team only mentioned the new multi-signing protocol but there was note of a future post that will set out to describe threshold signatures, a related concept that makes possible to produce signatures without contribution from the entire group.
The team is also developing new techniques for making nonce randomness safer to produce and more verifiable. Blockstream is aiming to leverage the power of zero-knowledge proofs to eliminate replay attacks and to remove the requirement for persistent memory reducing this way the MuSig protocol from three rounds to two.
Blockstream has made the new protocol test code available on GitHub and the team encourages everyone to test it and provide feedback!