MuSig2: New Advances in Bitcoin Multisignature

Bitcoin users prove the legitimacy of transactions through digital signatures and specific messages without exposing their private keys. As the network evolves, optimizing these signature schemes has become increasingly important. The introduction of Taproot provides developers with the opportunity to build improved signature schemes to enhance security, efficiency, and privacy. MuSig2, as an improved version of MuSig1, is the latest development in this field.

Overview of Bitcoin Multisignature Transactions

Multisignature transactions require multiple keys to authorize Bitcoin transfers, typically used to distribute ownership responsibilities or interact with layer two solutions. Although early multisignature technology had lower communication requirements, its privacy was not as good as 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. Compared to traditional methods, it uses less block space but requires more interaction among participants. MuSig1 supports key aggregation, simplifying multisignature transactions, reducing fees, and enhancing privacy.

Innovation of MuSig2

MuSig2 is an upgraded version of MuSig1, offering better security, efficiency, and privacy features. It requires only two rounds of communication among signers to create a valid signature, significantly reducing the complexity of multi-party coordination.

Comparison between MuSig1 and MuSig2

The main differences are reflected in the communication rounds and security model:

• MuSig1 requires three rounds of communication, while MuSig2 only needs two rounds.
• MuSig1 relies on the Random Oracle Model (ROM), while MuSig2 is based on the Algebraic Group Model (AGM), providing stronger security guarantees.

The Impact of MuSig2 on Bitcoin

1. Improve efficiency: Simplify multisignature transaction coordination.
2. Enhanced Privacy: Multisignature transactions are difficult to distinguish from single-signature transactions on the blockchain.
3. Greater flexibility: supports complex signing strategies, such as threshold signatures.
4. Enhanced Security: The AGM model provides stronger security guarantees.

Applications of MuSig2

1. Shared custody: Safely manage shared funds and reduce single point of failure risk.
2. Cold Storage: Create a multisignature cold storage solution to increase security layers.
3. Privacy Protection Wallet: Achieve multisignature transactions that are indistinguishable from single-signature transactions.
4. Layer 2 protocol optimization: used for Lightning Network, protecting off-chain transactions and improving efficiency.

The application of MuSig2 in the Liquid Network is also worth noting, as it can optimize the anchoring mechanism and simplify the bridge management of federated members. The Liquid Network has enabled Taproot, allowing L-BTC users to use MuSig2 in production environments, facilitating innovative interoperability between the base layer and the Liquid Network.

Conclusion

MuSig2, as an important advancement in Bitcoin multisignature technology, has significant improvements in security, efficiency, and privacy. It is expected to bring new application scenarios to the Bitcoin ecosystem and enhance the functionality of existing applications. With the maturity and widespread use of the technology, MuSig2 will play a key role in shaping the future of Bitcoin and blockchain technology.

For those looking to gain a deeper understanding of MuSig2, it is recommended to start with the official documentation and relevant research papers to gain a comprehensive understanding of the details and potential of this technology.