数字签名算法，使用RSA非对称密码算法，应该是非对称加密算法。DES是一种对称加密算法，不能做为数字签名的算法。对称加密算法由于加密和解密都是使用同一个密钥，所以无法保证密钥的完全保密（至少加密解密的两个人知道），也就不能唯一的确定加密者的身份。-Digital Signature Algorithm, using RSA asymmetric cryptographic algorithm should be non-symmetric encryption algorithm. DES is a symmetric encryption algorithm, and can not be used as a digital signature algorithm. Symmetric encryption algorithm, encryption and decryption using the same key, so I can not guarantee complete confidentiality of the key (at least two people know the encryption and decryption), it can not only determine the encryption identity.