需要引用名称空间

using System;using System.Text;using System.Security.Cryptography;using System.IO;

 

具体代码：

1     public class CryptoHelper 2     { 3         /// 
 4         /// 使用DES加密 5         /// 
 6         /// 明文 7         /// 加密钥匙 8         /// 向量 9         /// 
     
      返回密文
     10         public static string DesEncode(string plain, string key, string iv)11         {12             //把密钥转换成字节数组13             byte[] keyBytes = Encoding.ASCII.GetBytes(key);14 15             //把向量转换成字节数组16             byte[] ivBytes = Encoding.ASCII.GetBytes(iv);17 18             //声明1个新的DES对象 19             DESCryptoServiceProvider des = new DESCryptoServiceProvider();20 21             //开辟一块内存流22             MemoryStream msEncrypt = new MemoryStream();23 24             //把内存流对象包装成加密流对象 25             CryptoStream csEncrypt = new CryptoStream(msEncrypt, des.CreateEncryptor(keyBytes, ivBytes), CryptoStreamMode.Write);26 27             //把加密流对象包装成写入流对象28             StreamWriter swEncrypt = new StreamWriter(csEncrypt);29 30             //写入流对象写入明文  31             swEncrypt.WriteLine(plain);32 33             //写入流关闭  34             swEncrypt.Close();35 36             //加密流关闭  37             csEncrypt.Close();38 39             //把内存流转换成字节数组，内存流现在已经是密文了  40             byte[] bytesCipher=msEncrypt.ToArray();41 42             //内存流关闭 43             msEncrypt.Close();44             //将字节数组转化成Base64字符串45             return Convert.ToBase64String(bytesCipher);46         }47 48         public static string DesDeCode(string cipher, string key, string iv)49         {50             //将密文通过Base64位还原成字节数组51             byte[] cipherByte = Convert.FromBase64String(cipher);52 53             //把密钥转换成字节数组54             byte[] keyBytes = Encoding.ASCII.GetBytes(key);55 56             //把向量转换成字节数组57             byte[] ivBytes = Encoding.ASCII.GetBytes(iv);58 59             //声明1个新的DES对象 60             DESCryptoServiceProvider des = new DESCryptoServiceProvider();61 62             //开辟一块内存流，并存放密文字节数组63             MemoryStream msDecrypt = new MemoryStream(cipherByte);64 65             //把内存流对象包装成解密流对象 66             CryptoStream csDecrypt = new CryptoStream(msDecrypt, des.CreateDecryptor(keyBytes, ivBytes), CryptoStreamMode.Read);67 68             //把解密流对象包装成写入流对象69             StreamReader srDecrypt = new StreamReader(csDecrypt);70 71             //明文=读出流的读出内容   72             string strPlainText=srDecrypt.ReadLine();73 74             //读出流关闭  75             srDecrypt.Close();76 77             //解密流关闭  78             csDecrypt.Close();79 80             //内存流关闭  81             msDecrypt.Close();82 83             //返回明文  84             return strPlainText;85         }86     }