说明：  实现了三种古典密码学体制与DES体制及其分析。affine(仿射)读入文件11.txt中内容（小写字母，明文）加密并把内容写入12.txt，还能解密生成文件13.txt。vigenere，hiill体体制类似。DES体制包含加密解密雪崩效应差分分析等内容。由于本人还是刚学习程序源码设计语言及密码学的在校本科生，水平非常低，第一次上传只是为了试一下。能考虑少给几点，呵呵。 可直接使用。
(Three classical cryptography system and DES system and its analysis. affine (affine) read the contents of a file 11.txt (lowercase letters, plaintext) is encrypted and write the contents 12.txt can decrypt the generated file 13.txt. vigenere, hiill body system is similar. DES system contains the encryption and decryption of the contents of the avalanche effect differential analysis. I still just learning the language of the program source code and cryptography in the undergraduate level is very low, the first upload just to try. Can consider less to a few points. Can be used directly.)