基于访问树的策略隐藏属性加密方案

已有的策略隐藏属性加密（ABE，attribute-based encryption）方案只支持受限的访问结构，策略表达能力弱，基于此提出一种新的访问树结构，使属性隐藏和秘密共享能够应用到“与”门、“或”门和“门限”门中。并且，利用合数阶双线性群构造了一种基于访问树的策略隐藏方案，并通过双系统加密的概念证明了方案的安全性。分析和实验验证表明，方案在实现复杂访问结构的策略隐藏的同时，并没有过多地增加计算开销，在实际应用过程中更加灵活和有效。

Attribute-based encryption with hidden policies in the access tree

The existing policies-hidden attribute-based encryption (ABE) schemes could only support a limited access structure,which resulted in weak expressiveness.A new structure of access tree was thus proposed to integrate attribute hiding and secret sharing into “and” gate,“or” gate and “threshold” gate.Then,a tree-based policies-hidden scheme was constructed by using composite order bilinear groups.Under dual system encryption,the scheme was proved to be secure.Furthermore,the analysis and experiment demonstrate that the scheme realize policies-hidden in the complex ac-cess structure without increasing the overhead of computation.As a result,it is more feasible and flexible for applica-tions.