摘要:现有的密文策略基于属性加密CP-ABE（ciphertext-policy attribute-based encryption）算法普遍在解密时存在计算量过大、计算时间过长的问题，该问题造成CP-ABE难以应用和实施.针对该问题，将计算外包引入到方案的设计之中，提出一种面向公有云的基于Spark大数据平台的CP-ABE快速解密方案.在该方案中，专门根据CP-ABE的解密特点设计了解密并行化算法；利用并行化算法，将计算量较大的叶子节点解密和根节点解密并行化；之后，将并行化任务交给Spark集群进行处理.计算外包使得绝大多数解密工作由云服务器完成，用户客户端只需进行一次指数运算；而并行化处理则提高了解密速度.安全性分析表明，所提出的方案在一般群模型和随机预言模型下能对抗选择明文攻击.



Abstract:Most of existing CP-ABE (ciphertext-policy attribute-based encryption) schemes have such problems as over-computation and a long calculation time in decryption, which make them difficult to be applied and implemented. To solve this problem, the computation outsourcing is introduced into the design of CP-ABE scheme, a Spark-platform-based CP-ABE scheme with fast decryption for public cloud is proposed. In this scheme, the decryption parallelization algorithm is designed based on the decryption feature of CP-ABE, with which, decryption at both leaf node and root node with over-computation is parallelized. Then, the parallelization tasks are handed over to the Spark cluster. The computation outsourcing makes the most decryption computation done by cloud servers, while the user client only needs an exponential operation, and parallelization greatly improves the speed of decryption. Security analysis shows that the proposed scheme can fight against chosen plaintext attack under both the generic group model and the random oracle model.



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