public class Encrypt  {    //默认密钥向量    private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };       /// <summary>    /// DES加密字符串    /// </summary>    /// <param name="encryptString">待加密的字符串</param>    /// <param name="encryptKey">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 EncryptDES(string encryptString, string encryptKey)    {        byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));        byte[] rgbIV = Keys;        byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);        DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();        MemoryStream mStream = new MemoryStream();        CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);        cStream.Write(inputByteArray, 0, inputByteArray.Length);        cStream.FlushFinalBlock();        return Convert.ToBase64String(mStream.ToArray());    }      /// <summary>    /// DES解密字符串    /// </summary>    /// <param name="decryptString">待解密的字符串</param>    /// <param name="decryptKey">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 DecryptDES(string decryptString, string decryptKey)    {      byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey);      byte[] rgbIV = Keys;      byte[] inputByteArray = Convert.FromBase64String(decryptString);      DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();      MemoryStream mStream = new MemoryStream();      CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);      cStream.Write(inputByteArray, 0, inputByteArray.Length);      cStream.FlushFinalBlock();      return Encoding.UTF8.GetString(mStream.ToArray());    }  }