/// <summary>
/// DES加密字符串
/// </summary>
/// <param name="pToEncrypt">待加密的字符串</param>
/// <param name="sKey">加密密钥,要求为8位</param>
/// <returns>加密成功返回加密后的字符串，失败返回源串</returns>
public static string DesEncrypt(string pToEncrypt, string sKey)
{
     StringBuilder ret = new StringBuilder();
     try
     {
         DESCryptoServiceProvider des = new DESCryptoServiceProvider();
         byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
         des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
         des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
         MemoryStream ms = new MemoryStream();
         CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(),CryptoStreamMode.Write);
         cs.Write(inputByteArray, 0, inputByteArray.Length);
         cs.FlushFinalBlock();
         foreach (byte b in ms.ToArray())
         {
             ret.AppendFormat("{0:X2}", b);
         }
         return ret.ToString();
     }
     catch
     {
         return pToEncrypt;
     }
}

/// <summary>
/// DES解密字符串
/// </summary>
/// <param name="pToDecrypt">待解密的字符串</param>
/// <param name="sKey">解密密钥,要求为8位,和加密密钥相同</param>
/// <returns>解密成功返回解密后的字符串，失败返源串</returns>
public static string DesDecrypt(string pToDecrypt, string sKey)
{
     MemoryStream ms = new MemoryStream();
     try
     {
         DESCryptoServiceProvider des = new DESCryptoServiceProvider();
         byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
         for (int x = 0; x < pToDecrypt.Length / 2; x++)
         {
             int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
             inputByteArray[x] = (byte)i;
         }
         des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
         des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
         CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
         cs.Write(inputByteArray, 0, inputByteArray.Length);
         cs.FlushFinalBlock();
         return System.Text.Encoding.Default.GetString(ms.ToArray());
     }
     catch
     {
         return pToDecrypt;
     }
}