MuSig2: A New Breakthrough in Bitcoin Multisignature

In the Bitcoin network, users prove the legitimacy of transactions through digital signatures and specific messages without exposing their private keys. As the network evolves, optimizing the signature creation process has become increasingly important. The introduction of Taproot provides developers with the opportunity to build improved signature schemes to enhance security, efficiency, and privacy. Among them, MuSig2, as an upgraded version of MuSig1, brings new possibilities for multisignature transactions.

Multisignature Transaction Overview

Multisignature transactions require multiple keys to authorize, commonly used to decentralize Bitcoin ownership responsibilities or to communicate with second-layer solutions. Traditional multisignature methods like CHECKMULTISIG OP-code, while having lower communication requirements, do not offer the same level of privacy as MuSig1.

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 creates a single aggregated public key and a single signature through key aggregation, simplifying multisignature transactions, reducing transaction size, lowering fees, and enhancing privacy.

Innovation of MuSig2

MuSig2 is an advanced version of MuSig1, providing better security, efficiency, and privacy features. It requires only two rounds of communication between signers 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 requires two.
2. Security Model: MuSig1 relies on the random oracle model (ROM), while MuSig2 is based on the algebraic group model (AGM), providing stronger security guarantees.

The Contribution of MuSig2 to Bitcoin

1. Improve efficiency: The two-round communication model simplifies the coordination of multisignature transactions.
2. Enhanced Privacy: Key aggregation makes multisignature transactions difficult to identify on the blockchain.
3. Greater flexibility: supports more complex signing strategies.
4. Enhanced Security: AGM provides stronger security guarantees.

Application Scenarios of MuSig2

1. Shared custody: Multiple parties securely manage shared funds.
2. Cold Storage: Create a multisignature cold storage solution to increase security levels.
3. Privacy-protecting wallets: Create indistinguishable multisignature transactions.
4. Second Layer Protocol Improvements: Optimize second layer solutions such as the Lightning Network and Liquid Network.

Conclusion

MuSig2, as an important advancement in Bitcoin multisignature technology, provides improved security, efficiency, and privacy features. It has the potential to unlock new application scenarios and enhance existing applications, making Bitcoin more accessible and safer. As the technology matures and sees widespread use, MuSig2 will play a key role in shaping the future of Bitcoin and blockchain technology.