Proxy re-encryption (PRE) is a promising cryptographic structure for pervasive data sharing in cloud-based social networks, which enables a semi-trusted proxy to convert a ciphertext for Alice into a ciphertext for Bob without seeing the corresponding plaintext. Since the proxy is semi-trust, a PRE scheme which can resist the collusion attack will be of great practical value. Jiang et al. in 2015 and Kim and Jeong in 2016 have proposed collusion-resistant PRE (CR-PRE) schemes from the lattice by a similar technique, respectively. However, through the analysis of their schemes, the authors find that both of them have defects in the construction of the re-encryption key, which will lead to the re-encryption ciphertext cannot be decrypted or decrypted error with high probability. In this study, the authors first point out the defects in the work of Jiang et al.'s work and Kim and Jeong's work and propose an improved collusion-resistant unidirectional PRE scheme from lattice, based on learning with errors problems. In addition to solving the defects, CR-PRE still has many useful properties similar to the previous schemes, such as unidirectional, collusion resistant, chosen-plaintext attack secure and so on.

中文翻译：

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莱迪思改进的抗串通的单向代理重加密方案

代理重新加密（PRE）是一种有前途的密码结构，用于在基于云的社交网络中进行广泛的数据共享，这使半信任的代理可以将Alice的密文转换为Bob的密文，而无需查看相应的明文。由于代理是半信任的，因此可以抵抗串通攻击的PRE方案具有很大的实用价值。江等。2015年和Kim和Jeong在2016年分别通过类似的技术从晶格中提出了抗共谋PRE（CR-PRE）方案。然而，通过对它们的方案的分析，作者发现它们两者在重新加密密钥的构造上都有缺陷，这将导致重新加密密文无法被解密或被解密的可能性很高。在这个研究中，作者首先指出了Jiang等人的工作以及Kim和Jeong的工作中的缺陷，并在学习有错误的基础上，提出了一种改进的基于格点的抗共谋单向PRE方案。除了解决这些缺陷外，CR-PRE还具有许多与以前的方案相似的有用属性，例如单向，抗串通，选择明文攻击安全等。