摘要
密码体制的完善保密性是衡量保密系统安全性的重要方法。通过深入分析密码体制的明文空间、密文空间、密钥空间及密钥概率之间的关系,给出并证明了两个特殊密码体制具有完善保密性的必要条件;提出了一种构造完善保密密码体制的实现方案和4个相关的条件;对一类尚未解决的特殊完善保密密码体制的存在性问题给出了相应的结论和证明;并总结了一类无法构造完善保密密码体制的明文空间、密文空间、密钥空间之间的参数关系,进一步收敛了构造完善保密密码体制的条件。
Perfect secrecy of cryptosystem is one of the important methods weighing the security of secrecy system.Based on the deep analysis of the relationship among plaintext size, ciphertext size, key size and the key probability of perfect secrecy of cryptosystem, two necessary conditions for special perfect secrecy cryptosystem were presented and proved. hhis paper suggested an approach to build perfect secrecy cryptosystem and summarized four correlated restriclions. By researching a question about the existence of a sort of special perfect secrecy cryptosystem which does not be solved, this paper gave the conclusion and correlative proof; furthermore, this paper got a group of relationship of parameter among plaintext size, ciphertext size, and key size, and proved that perfect secrecy cryptosystem can not be built in this way. The results contract the conditions to build perfect secrecy cryptosystem and develop communication theory of Shannon＇s secrecy system and arc helpful for designing secure cryptosystem.
出处
《计算机科学》
CSCD
北大核心
2010年第5期99-102,共4页
Computer Science
基金
国家自然科学基金(No.60903196和60903175)
湖北省自然科学基金(No.2009CDB379)资助
关键词
密码学
密码体制
完善保密
计算安全性
等价密钥
Cryptography Cryptosystem Perfect secrecy Computational security Equivalent keys
