选择性隐藏访问结构的OO-CP-ABE

密文策略属性基加密(Ciphertext-Policy Attribute-Based Encryption, CP-ABE)是目前最适合用于云中的加密方案之一,CP-ABE具有灵活的访问结构,但是在CP-ABE中访问结构可能泄露风险信息,现有的CP-ABE方案,要么完全公开访问结构,要么将其完全隐藏,这将导致策略保密性差或方案加解密计算量大。本文提出选择性隐藏访问结构OO-CPABE,该方案利用属性之间的互信息筛选出访问结构中的部分属性,此部分属性包含原始属性集中的绝大部分或者全部信息量,并隐藏这部分属性。此选择性隐藏与完全隐藏有相同的策略隐藏效果,能有效地降低加解密计算量。与公开访问结构的方案相比,能提高策略的安全性。此外,本文还用在线/离线加密和部分解密减少加解密阶段的计算量。

OO-CP-ABE SCHEME WITH SELECTIVELY-HIDDEN ACCESS STRUCTURE

Ciphertext-Policy Attribute-Based Encryption(CP-ABE) is one of the most suitable encryption schemes for cloud. CP-ABE has a flexible access structure. However, in CP-ABE, the access structure may leak risk information. The existing CP-ABE either completely expose or completely hide the access structure, resulting in either poor policy confidentiality or heavy computation overhead of both encryption and decryption. We propose a OO-CP-ABE with selectively-hidden access structure. It uses the mutual information to extract partial attributes, which contains almost all information that the original attributes in the access structure and hides these extracted attributes. This scheme has nearly the same policy privacy as fully hiding, meanwhile effectively reduces the computational burden of both the encryption and decryption. Compared to the scheme of open access structure, the confidentiality of policy is improved. In addition, we also use online/offline encryption and partial decryption to reduce the amount of computation in the encryption and decryption phase.