Cascade ciphers: The importance of being first
Cascade ciphers: The importance of being first
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级联密码：成为第一的重要性
DOI：
10.1007/bf02620231
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发表时间：
1993
影响因子：
3
通讯作者：
J. Massey
中科院分区：
文献类型：
--
作者：
U. Maurer;J. Massey
考虑了级联密码的安全性，其中，根据定义，各组成密码的密钥是独立的。它是由一个反例表明，直观的结果，正式声明和证明在文献中，级联至少是最强的组件密码一样强，需要无趣的限制性假设，敌人不能利用有关明文统计信息。它被证明，对于破解密码和问题难度的非常一般的概念，级联至少和第一个组成密码一样难以破解。该结果的结果是，如果密码互换，则级联至少与最难破解的分量密码一样难破解，即，密码链至少与其最强链接一样强的直觉是可以证明正确的。值得注意的是，加法流密码确实是可交换的，这一事实被用来建议一种设计安全实用密码的策略。在密码学中的其他应用给出了用于证明级联密码结果的参数。
The security of cascade ciphers, in which by definition the keys of the component ciphers are independent, is considered. It is shown by a counterexample that the intuitive result, formally stated and proved in the literature, that a cascade is at least as strong as the strongest component cipher, requires the uninterestingly restrictive assumption that the enemy cannot exploit information about the plaintext statistics. It is proved, for very general notions of breaking a cipher and of problem difficulty, that a cascade is at least as difficult to break as the first component cipher. A consequence of this result is that if the ciphers commute, then a cascade is at least as difficult to break as the most-difficult-to-break component cipher, i.e., the intuition that a cryptographic chain is at least as strong as its strongest link is then provably correct. It is noted that additive stream ciphers do commute, and this fact is used to suggest a strategy for designing secure practical ciphers. Other applications in cryptology are given of the arguments used to prove the cascade cipher result.