可追踪并撤销叛徒的属性基加密方案

An Attribute-Based Encryption Scheme for Traitor Tracing and Revocation Together

属性基加密(ABE)是一种有效地对加密数据实现细粒度访问控制的密码学体制.在ABE系统中,存在恶意用户(或叛徒)泄露私钥生成盗版解码器,并将其分发给非法用户的问题.现有的解决方案仅能追查到密钥泄漏者的身份,但不能将其从ABE系统中撤销.文中提出了一种既可追踪又可撤销叛徒的属性基加密方案(ABTR).首先,给出一个具有扩展通配符的属性基加密方案(GWABE),基于3个3素数子群判定假设,采用双系统加密方法证明该GWABE方案是完全安全的.然后,利用完全子树构架将GWABE转化成ABTR方案,并证明该ABTR方案是完全安全的,且用户私钥长度是固定的.而此前的可追踪叛徒的ABE方案仅满足选择安全性.

Attribute based encryption （ABE） is an effective cryptographic primitive for achieving fine-grained access control of encrypted data. A well-known concern in the ABE system is that malicious users （or traitors） leak their private keys to construct pirate decryption devices and dis- tribute them to illegal users. The existing solutions can only trace the idewfities of users who leaked their keys, but they can not revoke the leaked keys from the ABE system. This paper pro- poses an attribute-based encryption scheme for traitor tracing and revocation together （ABTR）. We first introduce an ABE scheme with generalized wildcards （GWABE）. Under three assump- tions of the subgroup decision problem for 3 primes （3P-SDP）, we prove that the GWABE scheme is fully secure by using the dual system encryption method. Then we transform the GWABE scheme into an ABTR scheme by using the complete subtree framework. The ABTR scheme is proved to be fully secure, and provides the nice feature of having constant private key size. However, the previous ABE schemes for traitor tracing were only proved secure in the selective model.