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以前对保密增强理论的研究都是基于这样一个前提:敌手是被动攻击者,即敌手只能在公共信道上进行窃听而不能篡改信道上所传递的信息。本文主要研究能够防主动攻击的保密增强:借助于通信双方间共享的部分保密串作为认证密钥,实现信息理论安全认证以防止主动攻击。同时得出结论:如果敌手关于部分保密串的最小熵至少是串长的2/3,那么,只要部分保密串足够长,防主动攻击的保密增强就有可能实现。此外还给出了保密增强能够提取出的高度保密串的长度与敌手关于部分保密串的最小熵的关系。
The previous research on the theory of privacy enhancement is based on the premise that the adversary is a passive attacker, that is, the adversary can only eavesdrop on the public channel and can not alter the information conveyed on the channel. This paper mainly studies the security enhancements that can prevent active attacks: With the help of the partial secret strings shared between the two communication parties as authentication keys, the information theory security authentication can be implemented to prevent active attacks. We also conclude that if the adversary’s minimum entropy for partial security strings is at least 2/3 of the length of the string, as long as some of the security strings are long enough, it is possible to achieve increased privacy protection against aggressive attacks. In addition, the relationship between the length of the highly confidential string that can be extracted by the confidentiality enhancement and the minimum entropy of the adversary part of the confidential string is also given.