区块链因具有分布式、不可篡改和不变性的特点而广受关注,但区块链中使用的国际密码算法存在一定的后门安全隐患.现基于国密算法SM2,结合无证书密码机制,提出了一种基于区块链的无证书公钥加密(Certificateless Public Key Encryp-tion,CL-PKE)方案.该方案不依赖双线性配对,降低了计算成本,消除了证书管理和密钥托管问题,并且利用区块链不可篡改和可追溯的优点,实现了用户对公钥的更新与撤销,同时能够对抗无证书机制中的Type-1和Type-2型敌手.该方案基于计算性Diffie-Hellman问题(Computational Diffie-Hellman Problem,CDHP)的困难性,在随机预言模型中被证明在自适应选择密文攻击下具有不可区分性.最后进行性能分析与测试,结果表明,与现有CL-PKE方案相比,该方案的计算效率至少提升11％.
Blockchain Certificateless Encryption Mechanism Based on National Secret Algorithm
The blockchain has attracted widespread attention because of its distributed,non-tamperable and inherent immutability features.However,the international cryptographic algorithm used in the blockchain has certain backdoor security risks.Based on the national secret algorithm SM2,this paper proposes a blockchain-based certificateless public key encryption(CL-PKE)scheme,which combines with the certificateless cryptographic mechanism.The scheme does not use bilinear pairing,reduces computa-tional cost,and eliminates certificate management and key escrow issues.At the same time,due to tamper proof and traceable of blockchain,the scheme realizes the user's updating and revocation of the public key,so as to fight against Type-1 and Type-2 ad-versaries in the certificateless mechanism.Based on the difficulty of the computational Diffie-Hellman problem(CDHP),it is proved that the scheme is indistinguishable under the adaptive chosen ciphertext attack in the random prediction model.Finally,after analysis and testing,compared with the existing CL-PKE schemes,the computational efficiency of this scheme is increased by at least 11％.
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