在线/离线非单调CP-ABE方案构造

提出了支持非单调访问结构的在线/离线的CP-ABE方案。在离线加密阶段,完成了密文的主要构成部分的计算;在线加密阶段,将正属性集合上的非单调访问控制结构转变成由正、负属性集合上的基于线性秘密共享方案的单调访问控制结构,利用少量的加法和乘法操作生成密文的其余构成部分。在n-(B)假设成立条件下,证明了该方案具有选择性安全性。与原来的非单调CP-ABE方案相比,该方案系统参数和私钥规模保持不变,加密的总体计算复杂度仅有少量增加,但在线加密阶段的计算复杂度较小,可与解密外包服务相结合,使得该方案的离线加密和解密阶段都可在资源受限的小型设备上完成。

A compact construction for non-monotonic online/offline CP-ABE

We proposed an online/offline ciphertext-policy attribute-based encryption scheme that could support non-monotonic access structure. In the offline phase, most of the computations for encryption are done; in the online phase, we transform the non-monotonic access structure with positive attribute sets into a monotonic access structure which is based on the linear secret sharing scheme with positive and negative attribute sets, then it only needs a small amount of addition and multiplication operations for the rest components of encryption. The selective security of the scheme under the n-(B)assumption was proved. Compared with the original non-monotonic CP-ABE scheme, our scheme remains the same on the public keys and the master secret keys, with only a small increase in computational complexity. However, the computational complexity during online phase is very small. We can combine our scheme with outsourcing techniques, thus the online encryption phase and the decryption phase could be completed on the resource-constrained small devices.