支持离线/在线加密及可验证外包解密的CP-WABE方案

已有的支持在线/离线加密和外包解密的基于属性加密的方案可实现细粒度访问控制和数据保密性，但无法实现同一属性之间的层次关系的表达和数据防篡改，并且终端需要在离线加密之前确定用户的访问结构，每次加密都需重新生成中间密文.针对上述问题，本文提出了一种支持离线/在线加密及可验证外包解密的CP-WABE（Ciphertext-Policy Weighted Attribute-Based Encryption）方案.该方案通过权重集合来实现同一属性层次关系的灵活表达，可实现一次离线加密就产生不同访问结构的数据的中间密文，在线仅需要少量开销就可完成加密，同时对外包解密的正确性进行了验证.最后对方案进行了安全性和性能分析，实验仿真也表明了本文对比相关方案更具优势.

A CP-WABE Scheme Supports Offline/Online Encryption and Verifiable Outsourced Decryption

Existing attribute-based encryption schemes which support online/offline outsourcing encryption and decryption can realize fine-grained access control and data confidentiality,but it cannot achieve the expression of hierarchical relationships between the same attributes and prevent data from being tampered.Besides,the terminal needs to determine the user's access structure before offline encryption,and the intermediate ciphertext needs to be regenerated every time.Aiming at the above problems,this paper proposes a CP-WABE (Ciphertext-Policy Weighted Attribute-Based Encryption) scheme supports offline/online encryption and verifiable outsourced decryption.The scheme realizes the flexible expression of the hierarchical relation of the same attributes through the weight sets,which can realize the generation of intermediate ciphertext of the data with different access structure after one offline encryption,and complete the online encryption with only a small amount of overhead.At the same time,the correctness of outsourced decryption is verified.Finally,the security and performance of the scheme are analyzed,and the experimental simulation also shows that this paper has more advantages than the related schemes.