可追踪密钥的策略隐藏属性基加密方案

传统的属性基加密方案中存在着访问策略所包含的属性会泄露用户的敏感信息以及恶意用户泄露私钥获取非法利益而不会被追责的问题。同时私钥长度、密文长度和解密运算量均会随属性数量增加而带来较大的通信开销和计算开销。针对以上问题提出了一种可追踪且隐藏访问结构的属性基加密方案。该方案在不影响加/解密效率的前提下提高了加密算法的安全性，并采用双因子身份认证机制实现了更安全高效的访问控制。并且引入一个安全的签名机制用于支持可追踪密钥来追踪恶意用户。该方案基于DBDH假设，在标准模型下被证明是安全的。

Policy-hidden attribute-based encryption scheme with traceable keys

In the traditional attribute-based encryption scheme, there are problems that the attributes contained in the access policy may leak sensitive information of the user and the malicious user leaks the private key to gain illegal profits without being blamed. At the same time, with the increasing of the number of attributes the length of the private key, ciphertext, and the decryption operation will increase and it bring greater communication overhead and computational overhead. To solve these problems, this paper proposed an attribute-based encryption scheme that can track keys and hide the access structure. The scheme improved the security of the encryption algorithm without affecting the efficiency of encryption and decryption. The scheme adopted a two-factor authentication mechanism to achieve more secure and efficient access control, and it used a secure signature mechanism for supporting traceable keys to track malicious users. Finally, the theoretical analysis show that our scheme proved to be safe under the standard model based on the DBDH hypothesis.