基于身份的单向多用的代理重加密方案

Identity-based multi-use and unidirectional proxy re-encryption scheme

针对大多单向多用的代理重加密方案存在密文大小、计算代价会随着重加密的次数增多而增加的问题,在Toshihiko的代理重加密方案的基础上,构造了一个基于身份的单向多用的代理重加密方案。相比已有的基于身份的代理重加密方案,方案需要密钥生成中心为用户生成两类密钥,一类用于解密密文的密钥;另一类用于重加密的密钥。新方案具有固定密文长度,并在随机预言模型下证明了安全性。

The authors found one drawback of some existing multi-use and unidirectional PRE schemes which the ciphertext size and computational complexity expanded with respect to the number of re-encryptions. Therefore,based on Toshihiko＇s scheme,this paper constructed an identity-based multi-use and unidirectional proxy re-encryption scheme. In comparison with existed identity-based proxy re-encryption schemes,the proposed scheme needed the private key generator to generate two kinds of keys for users,one was decryption private key that was employed in decryption process and the other was proxy private key that helped users to translate ciphertexts. In the new scheme,the size of ciphertext is constant regardless of how many times it has been re-encrypted,and it can be proved secure in random oracle model.