DES-固定密鑰-加密-解密

/// <summary>
        /// 進行DES加密。
        /// </summary>
        /// <param name="pToEncrypt">要加密的字符串。</param>
        /// <param name="sKey">密鑰，且必須為8位。</param>
        /// <returns>以Base64格式返回的加密字符串。</returns>
        public static string DESEncrypt(string pToEncrypt,string strkey)
        {
            try
            {
                using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
                {
                    byte[] inputByteArray = Encoding.UTF8.GetBytes(pToEncrypt);
                    des.Key = ASCIIEncoding.ASCII.GetBytes(strkey.Substring(0,8));
                    des.IV = IVKeys;
                    System.IO.MemoryStream ms = new System.IO.MemoryStream();
                    using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(inputByteArray, 0, inputByteArray.Length);
                        cs.FlushFinalBlock();
                        cs.Close();
                    }
                    string str = Convert.ToBase64String(ms.ToArray());
                    ms.Close();
                    return str.Replace("+", "_");
                }
            }
            catch
            {
                return "";
            }
        }

/// <summary>
        /// 進行DES解密。
        /// </summary>
        /// <param name="pToDecrypt">要解密的以Base64</param>
        /// <param name="sKey">密鑰，且必須為8位。</param>
        /// <returns>已解密的字符串。</returns>
        public static string DESDecrypt(string pToDecrypt, string strkey)
        {
            try
            {
                byte[] inputByteArray = Convert.FromBase64String(pToDecrypt.Replace("_", "+"));
                using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
                {
                    des.Key = ASCIIEncoding.ASCII.GetBytes(strkey.Substring(0, 8));
                    des.IV = IVKeys;
                    System.IO.MemoryStream ms = new System.IO.MemoryStream();
                    using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(inputByteArray, 0, inputByteArray.Length);
                        cs.FlushFinalBlock();
                        cs.Close();
                    }
                    string str = Encoding.UTF8.GetString(ms.ToArray());
                    ms.Close();
                    return str;
                }
            }
            catch
            {
                return "";
            }
        }