支持属性撤销的适应性安全属性基加密方案

Adaptively Secure Attribute-Based Encryption Supporting Attribute Revocation

Attribute revocation is inevitable and also important for Attribute-Based Encryption (ABE) in practice. However, little attention has been paid to this issue, and it remains one of the main obstacles for the application of ABE. Most of existing ABE schemes support attribute revocation work under indirect revocation model such that all the user's private keys will be affected when the revocation events occur. Though some ABE schemes have realized revocation under direct revocation model such that the revocation list is embedded in the ciphertext and none of the user's private keys will be affected by revocation, they mostly focused on the user revocation that revokes the user's whole attributes, or they can only be proven to be selectively secure. In this paper, we first define a model of adaptively secure ABE supporting the attribute revocation under direct revocation model. Then we propose a Key-Policy ABE (KP-ABE) scheme and a Ciphertext-Policy ABE (CP-ABE) scheme on composite order bilinear groups. Finally, we prove our schemes to be adaptively secure by employing the methodology of dual system encryption.