基于NTRU的单向抗合谋代理重加密方案

代理重加密方案中,一个半可信的代理使用重加密密钥将授权者公钥加密的密文转换成可用被授权者私钥解密的密文. Nunez等人首次提出了基于NTRU的代理重加密方案,但该方案是可以双向重加密的,且不能抗合谋攻击.本文设计一种新的重加密密钥生成算法,使得代理者不能与授权者或被授权者合谋获得另外一方的私钥,给出了基于NTRU的高效且能抗合谋攻击的代理重加密方案,支持单向重加密,并支持多跳性,并给出方案的详细设计和安全性证明.

A Collusion-resistant and Uni-directional Proxy Re-encryption Scheme Based on NTRU

In a proxy re-encryption system, a semi-trusted proxy can use a re-encryption key to convert a ciphertext encrypted by a delegator’s public key into a ciphertext that can be decrypted by a delegatee’s private key. An NTRU-based proxy re-encryption scheme was first presented by Nunez et al., however, that scheme is bi-directional and cannot resist the collusion attacks. This paper proposes a new scheme to improve the security for generating a re-encryption key so that the proxy cannot collude with the delegator or the delegatee to obtain the private key of the other parties. We give the concrete construction that supports the collusion resistance and implements the directional delegation,and finally we provide the performance analysis and security proof.