| 摘要: |
| 匿名凭证作为一种隐私保护的数字身份认证技术, 在认证用户数字身份有效性的同时, 能够保护用户身份隐私, 广泛应用于匿名身份认证、匿名通证、去中心化的数字身份管理系统等. 现有的匿名凭证通常采用承诺-签名-证明的构造范式, 通常要求采用的签名算法具备重随机化特性, 如CL系列签名、PS系列签名及结构保持签名. 现实应用中多采用ECDSA、Schnorr、SM2等数字签名进行数字身份认证, 但其缺乏对用户身份隐私的保护. 因此, 在认证的同时, 保护身份的隐私性, 构造兼容ECDSA、Schnorr、SM2等数字签名的匿名凭证具有一定的现实意义. 探索基于SM2数字签名构造匿名凭证协议的方法. 在申请证书阶段, 借助Pedersen承诺对用户属性进行承诺, 同时依据SM2签名消息为$ H(m) $的结构特点, 证明Pedersen承诺消息与哈希承诺中消息的相等性. 为实现这种代数结构和非代数结构陈述的等价性证明, 借鉴ZKB++技术对承诺消息进行转化, 进而实现跨域证明, 并签发基于SM2数字签名的授权证书. 在匿名凭证展示阶段, 结合零知识证明技术证明持有SM2数字签名, 保证了用户的匿名性. 给出基于SM2数字签名的匿名凭证协议的具体构造, 并进一步证明该协议的安全性. 最后, 通过对协议的计算复杂度分析与算法执行效率测试验证协议的有效性和可用性. |
| 关键词: SM2 匿名凭证协议 零知识证明 ZKB++ |
| DOI：10.13328/j.cnki.jos.006929 |
| 分类号:TP309 |
| 基金项目:国家重点研发计划(2022YFB2701500); 国家自然科学基金(61872229, U19B2021, 62202375, 62202339); 陕西省杰出青年基金(2022JC-47); 陕西省科协高校青年托举人才计划(20220134); 陕西省重点研发计划(2021ZDLGY06-04, 2020ZDLGY09-06); 陕西省自然科学基础项目(2022JQ-604); 陕西省教育厅科学研究项目(22JK0557) |
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| Anonymous Credential Protocol Based on SM2 Digital Signature |
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ZHAO Yan-Qi1, YANG Xiao-Yi2, FENG Qi3, YU Yong4
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1.School of Cyberspace Security, Xi’an University of Posts and Telecommunications, Xi’an 710121, China;2.Department of Computing, The Hong Kong Polytechnic University, Hong Kong 999077, China;3.School of Cyber Science and Engineering, Wuhan University, Wuhan 430040, China;4.School of Computer Science, Shaanxi Normal University, Xi’an 710119, China
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| Abstract: |
| As a privacy-preserving digital identity authentication technology, anonymous credentials not only authenticate the validity of the users’ digital identity but also protect the privacy of their identity. Anonymous credentials are widely applied in anonymous authentication, anonymous tokens, and decentralized digital identity systems. Existing anonymous credentials usually adopt the commitment-signature-proof paradigm, which requires that the adopted signature scheme should have the re-randomization property, such as CL signatures, PS signatures, and structure-preserving signatures (SPS). In practical applications, ECDSA, Schnorr, and SM2 are widely employed for digital identity authentication, but they lack the protection of user identity privacy. Therefore, it is of certain practical significance to construct anonymous credentials compatible with ECDSA, Schnorr, SM2, and other digital signatures, and protect identity privacy during the authentication. This study explores anonymous credentials based on SM2 digital signature. Pedersen commitment is utilized to commit the user attributes in the registration phase. Meanwhile, according to the structural characteristics of SM2, the signed message is H(m), and the equivalence between the Pedersen commitment message and the hash commitment message is proven. This study also employs ZKB++ technology to prove the equivalence of algebraic and non-algebraic statements. The commitment message is transformed to achieve the cross-domain proof and issue the users’ credentials based on the SM2 digital signature. In the showing phase of anonymous credentials, the zero-knowledge proof is combined to prove the possession of an SM2 signature and ensure the anonymity of credentials. This study provides the construction of an anonymous credential protocol based on SM2 digital signature and proves the security of this protocol. Finally, it also verifies the effectiveness and feasibility of the protocol by analyzing the computational complexity of the protocol and testing the algorithm execution efficiency. |
| Key words: SM2 anonymous credentials protocol zero-knowledge proof ZKB++ |
