对依赖密钥的明文进行安全加密的性质研究

项目名称： 对依赖密钥的明文进行安全加密的性质研究

项目编号： No.61472414

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 自动化技术、计算机技术

项目作者： 薛锐

作者单位： 中国科学院信息工程研究所

项目金额： 81万元

中文摘要： 在现代密码学中，如何使用适当安全的加密是最重要、最基本的任务之一。近年来出现的新的安全性定义--对于依赖于密钥的明文(Key-Dependent Message，KDM)加密的安全性要求:即使敌手得到了私钥的某些函数(来自于某一函数族)值的密文，也不能获得新的密文所对应明文的任何信息。这一安全性因其新颖性和实用性，引起很多密码学家关注和研究, 取得了许多研究成果。但是，还有很多重要的公开问题未被解决。本项目将从函数族的大小、方案的效率、安全性的强弱以及所依赖的假设等方面对KDM安全性进行系统而充分的研究和探讨。期望能够构造出对更广的函数族满足KDM安全的方案来。并期望能在尽可能弱的假设基础上，构建满足更强的KDM安全方案。在应用方面，我们试图建立KDM安全性与其他的密码理论或工具之间更多的联系拓展其应用范围；同时, 将最新的研究成果转化到实际应用中。

中文关键词： 明文依赖密钥；选择密文攻击；函数族；公钥加密

英文摘要： In modern cryptography, one of important tasks is to explore the security definitions that are used in real world. Recently, a new kind of security definition called Key-Dependent Message (KDM) security has been proposed. It essentially requires that, in an encryption scheme, it is infeasible for an adversary to obtain information of a message from its ciphertext even if the adversary has access to other encryptions of messages that can been seen as functions of the secret keys (the functions are chosen from some ensembles). Many cryptographers focus on the research about it for its novelty and practical applications, and obtain many interesting results. However, there are still many important open problems left to be resolved. Our aims here are to make a systematic and an intensive study on KDM securities from a whole including the size of function ensemble, the efficiency of the schemes, the rank of security as well as the assumptions security based on in the schemes. We will seek the schemes achieving KDM security with respect to larger ensembles as well as those with stronger KDM security which is based on weaker assumptions. For applications, we try to establish even richer relationships between the KDM security and other cryptographic primaries and tools so as to apply our new results to practice.

英文关键词： Key-Dependent Message;Chosen-Ciphertext Attack;Function Ensemble;Public Key Encryption