MuSig2: New Developments in Bitcoin Multisignature

Bitcoin users prove the legitimacy of transactions through digital signatures and specific messages without exposing their private keys. As the Bitcoin network evolves, optimizing the way signatures are created has become an important topic. The introduction of Taproot provides developers with the opportunity to build improved signature schemes to enhance security, efficiency, and privacy. MuSig2, as one of the latest developments, aims to improve the performance of multisignature transactions.

Bitcoin Multisignature Transaction Overview

Multisignature transactions require multiple keys for authorization, typically used to decentralize the ownership responsibility of Bitcoin or to interact with second-layer solutions. Traditional multisignature technologies like CHECKMULTISIG OP-code have lower communication requirements but lack the privacy of the MuSig1 scheme.

Introduction to MuSig1

MuSig1 is a multisignature scheme based on Schnorr signatures that allows multiple parties to jointly sign a single message or transaction. It simplifies multisignature transactions through key aggregation, reducing transaction size, lowering fees, and enhancing privacy. However, MuSig1 requires more interaction among participants.

MuSig2: Upgraded Multisignature Scheme

MuSig2 is an improved version of MuSig1, providing better security, efficiency, and privacy features. It is a two-round multisignature scheme that requires only communication between the signers in two rounds to create a valid signature, significantly reducing the complexity of multi-party coordination.

The Main Differences Between MuSig1 and MuSig2

1. Communication rounds: MuSig1 requires three rounds of communication, while MuSig2 only needs two.

2. Security Model: MuSig1 relies on the Random Oracle Model (ROM), while MuSig2 is based on the Algebraic Group Model (AGM), which provides stronger security guarantees.

The Impact of MuSig2 on Bitcoin

1. Improve efficiency: Simplify the coordination process of multisignature transactions.
2. Enhanced Privacy: Multisignature transactions on the blockchain are no different from single signature transactions.
3. Greater flexibility: supports more complex signing strategies.
4. Enhanced Security: AGM provides stronger security assurances.

Application Scenarios of MuSig2

1. Shared custody: Secure management of shared funds, reducing single point of failure risk.
2. Cold storage: Create a multisignature cold storage solution to add an extra layer of security.
3. Privacy Protection Wallet: Achieve multisignature transactions that are indistinguishable from single-signature transactions.
4. Second layer protocol improvements: Optimize the performance and security of second layer solutions such as the Lightning Network and Liquid Network.

Conclusion

MuSig2, as an important advancement in Bitcoin multisignature technology, provides users with a more efficient, safer, and more private way to transact. It is expected to play a key role in the future Bitcoin ecosystem, driving the development of new application scenarios and enhancing existing applications. As the technology matures and gains widespread use, MuSig2 will occupy a significant position in shaping the future of Bitcoin and blockchain technology.