一个对称密码技术的实现

（1）在单机完成对某个特定文件的单重DES加密/解密；

（2）针对DES密钥特点（8字节，64比特位，其中真正起作用的为56比特位），设计一次一密的密钥产生机制（即每次会话所使用的密钥都是临时随机产生的）-Implement a symmetric cryptographic technique

(1) In the single complete unit weight for a specific file DES encryption/decryption

(2) for the DES key characteristics (8 bytes, 64 bits, which really works for 56 bits), a mechanism designed to generate a secret key (ie, the key used for each session are temporary randomly generated)