Broadcast revocation scheme in composite-order bilinear group and its application to attribute-based encryption

Abstract

Broadcast revocation scheme allows a broadcaster to specify a revoked users list S in the broadcast ciphertext. Only the users outside S can decrypt the broadcast ciphertext. Attribute-Based Encryption ABE is a useful cryptographic primitive which enables flexible access policy over encrypted data. In this paper, we propose an adaptively secure broadcast revocation scheme in composite-order bilinear group. After that, a fully secure and efficient broadcast revocable ciphertext-policy ABE scheme has been constructed based on the original revocation scheme. The security of the two encryption schemes can be proved through the famous dual system encryption methodology and reduced to the same three static intractable assumptions. Furthermore, our revocable ciphertext-policy ABE scheme enjoys fully collusion resistance and unbounded users revocation.