渤海5号钻井平台:既然有人使用密码，那么有是谁第一个破解密码呢？

第一个发现字母频率的不同可以用来破解密码的人，没有在历史上留下姓名，而最早记录这种方法的则是九世纪的“阿拉伯哲人”阿辛地 (al-Kindi) 。阿辛地的著作涉及医药，天文，数学，语言学和音乐，共达290本之多。他最杰出的论文，解码手册 (A Manuscript on Deciphering Cryptographic Message) 于1987年在伊斯坦布尔被重新发现。虽然论文中详细讨论了统计学，阿拉伯语音学和阿拉伯语法，阿辛地关于密码分析学的关键描述只有两小段。

One way to solve an encrypted message, if we know its language, is to find a different plaintext of the same language long enough to fill one sheet or so, and then we count the occurences of each letter. We call the most frequently occuring letter the "first", the next most frequently occuring letter the "second", the following most frequently occuring letter the "third", and so on, until we account for all the different letters in the plaintext sample.[cchere.com 西西河 阿康]

Then we look at the cipher text we want to solve and we also classify its symbols. We find the most occuring symbol and change it to the form of the "first" letter of the plaintext sample, the next most common symbol is changed to the form of the "second" letter, and the following most common symbol is changed to the form of the "third" letter, and so on. until we account for all symbols of the cryptogram we want to solve.