实现对单文件的DES加密解密，不限制大小，DES加密部分自写，非调用，用于学习DES原理。-The realization of the single document DES encryption and decryption, no limit to the size, DES encryption part self written, non call, for learning DES principle.

给文件夹加密解密，功能全，体积小，好代码-To the folder encryption and decryption, full-featured, small size, good code