CAJ | 학술논문

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.
밀마체제적완선보밀성시형량보밀계통안전성적중요방법.통과심입분석밀마체제적명문공간、밀문공간、밀약공간급밀약개솔지간적관계,급출병증명료량개특수밀마체제구유완선보밀성적필요조건;제출료일충구조완선보밀밀마체제적실현방안화4개상관적조건;대일류상미해결적특수완선보밀밀마체제적존재성문제급출료상응적결론화증명;병총결료일류무법구조완선보밀밀마체제적명문공간、밀문공간、밀약공간지간적삼수관계,진일보수렴료구조완선보밀밀마체제적조건.
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.This paper suggested an approach to build perfect secrecy cryptosystem and summarized four correlated restrictions.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 are helpful for designing secure cryptosystem.