支持策略隐藏的多授权机构属性基加密方案

摘要

Most existing attribute-based encryption schemes of hidden policies are directed to a single authority,without taking into account the situation where the users' attributes are managed by multi-authority,having the problems such as low-efficient of key generation,single authority easy to be broken through and requirement of environmental security inconsistent with cloud storage.Therefore,a multi-authority Attribute-based Encryption (ABE) scheme is put forward.This scheme realizes complete concealment of access policies so as to protect the privacy of users by improving the access structure.Users' private key is generated by the data owner and the attribute authorities,which improves the efficiency of key generation and resists conspiracy attack from illegal users and authorities.Based on Decisional Bilinear DiffieHellman (DBDH) assumption,the scheme is proved to be chosen-plaintext security under standard model.Experimental results indicate that this scheme can improve the efficiencies of key generation,encryption and decryption.%现有隐藏策略的属性基加密方案大多针对单个属性授权机构,没有考虑到用户属性由多个授权机构管理的情况,存在密钥生成效率低、机构本身易被攻破、无法满足云存储环境安全需求的问题.为此,提出一种多授权机构属性基加密方案.通过对访问结构进行改进,实现访问策略的完全隐藏,进而保护用户隐私.用户私钥由数据属主和多个属性授权机构共同生成,可提高密钥生成效率,并抵抗非法用户及授权机构的合谋攻击.基于判定性双线性Diffie-Hellman假设,证明方案在标准模型下是选择明文安全的.实验结果表明,该方案可有效提高密钥生成及加解密效率.