Abstract We present a stochastic method for breaking general periodic polyalphabetic substitution ciphers using only the ciphertext and without using any additional constraints that might come from the cipher’s structure. The method employs a hill-climbing algorithm for individual key alphabets, with occasional slipping down the hill. We implement the method with a computer and achieve reliable results for a sufficiently long ciphertext (150 characters per key alphabet). Because no constraints among the key alphabets are used, this method applies to any periodic polyalphabetic substitution cipher.

中文翻译：

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用于周期性多字母替换密码的仅密文密码分析的滑山爬山技术

摘要 我们提出了一种仅使用密文而不使用任何可能来自密码结构的附加约束来破解一般周期性多字母替换密码的随机方法。该方法对单个键字母采用爬山算法，偶尔会从山上滑下。我们用计算机实现了该方法，并获得了足够长的密文（每个密钥字母表 150 个字符）的可靠结果。由于没有使用密钥字母之间的约束，因此该方法适用于任何周期性多字母替换密码。