Notes

• BBS+/BBS signatures are key for anonymous credentials and privacy-preserving authentication, with increasing standardization and deployment.
• Existing threshold designs require at least three rounds and multi-kilobyte communication in two-party settings.
• New protocol uses only two passes with 0.85KB per signature, about 27% of the most bandwidth-efficient prior work (S&P'25).
• Competitive signing times (~62ms for one party, ~46ms for the other), efficient even for large message vectors (e.g., ℓ=500).
• Full simulation-based security proof in the standard real-ideal paradigm ensures protocol security.
• Naturally generalizable to 2-out-of-n threshold settings, enhancing flexibility and practical deployment appeal.

• BBS+/BBS签名是匿名凭证和隐私认证的关键组件，正被标准化和广泛应用
• 现有阈值方案在两方设置中至少需要三轮交互和数千字节通信
• 新协议仅需两轮交互，每签名通信0.85KB，比S&P'25方案减少约73%
• 签名时间高效（一方约62ms，另一方约46ms），支持大消息向量（如500条）
• 基于标准实理想范式的模拟安全证明，确保协议安全性
• 可自然扩展至2-out-of-n阈值设置，增强系统灵活性和部署吸引力