关键词: 代理重加密, 加密算法, 源隐藏特性, 选择密文攻击

Abstract: As Emura-IB-PRE ， an identity label-based proxy re-encryption scheme proposed by Emura et al. ， is of source hiding property and chosen ciphertext security in random oracle model ， a chosen ciphertext security method to attack Emura-IB-PRE scheme is proposed ， and Emura-IB-PRE is proved invalid in resisting the chosen ciphertext attack. In order to solve this problem ， an improved scheme named E-SH-IB-PRE is presented and the corresponding security proof is given. The results indicate the presented scheme is secure against chosen ciphertext attack with source hiding property in random oracle model ， and that the principle ， i.e. ， the first level ciphertext can be publicly verified by proxy ， is important for proxy re-encryption schemes.

Key words: proxy re-encryption, encryption algorithm, source hiding property, chosen ciphertext attack