C#的DES加解密

/// <summary>
        /// DES加密字符串
        /// </summary>
        /// <param name="encryptString">待加密的字符串</param>
        /// <param name="encryptKey">加密密鑰,要求爲8位</param>
        /// <returns>加密成功返回加密後的字符串，失敗返回源串</returns>
        public static string EncryptDES(string encryptString, string encryptKey)
        {
            try
            {
                byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
                byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
                byte[] rgbIV = rgbKey;

                DESCryptoServiceProvider csp = new DESCryptoServiceProvider();
                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, csp.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, 0, inputByteArray.Length);
                cStream.FlushFinalBlock();

                //返回的格式
                StringBuilder sBulider = new StringBuilder();
                byte[] tmp = mStream.ToArray();
                for (int i = 0; i < tmp.Length; i++)
                {
                    sBulider.AppendFormat("{0:X2}", tmp[i]);
                }
                return sBulider.ToString();
            }
            catch
            {
                return encryptString;
            }
        }

        /// <summary>
        /// DES解密字符串
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <param name="decryptKey">解密密鑰,要求爲8位,和加密密鑰相同</param>
        /// <returns>解密成功返回解密後的字符串，失敗返源串</returns>
        public static string DecryptDES(string decryptString, string decryptKey)
        {
            try
            {
                byte[] inputByteArray = new byte[decryptString.Length / 2];
                for(int i = 0; i < decryptString.Length / 2; i++)
                {
                    int num = Convert.ToInt32(decryptString.Substring(i * 2, 2), 16);
                    inputByteArray[i] = (byte)num;
                }

                byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey);
                byte[] rgbIV = rgbKey;

                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());
            }
            catch
            {
                return decryptString;
            }
        }