如何用C#實現DES加密解密

代碼如下：

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

namespace Common
...{
    /**//// <summary>
    /// DESEncrypt加密解密算法。
    /// </summary>
    public sealed class DESEncrypt
    ...{
        private DESEncrypt()
        ...{
            //
            // TODO: 在此處添加構造函數邏輯
            //
        }

        private static string key = "zhoufoxcn";

        /**//// <summary>
        /// 對稱加密解密的密鑰
        /// </summary>
        public static string Key
        ...{
            get
            ...{
                return key;
            }
            set
            ...{
                key = value;
            }
        }

        /**//// <summary>
        /// DES加密
        /// </summary>
        /// <param name="encryptString"></param>
        /// <returns></returns>
        public static string DesEncrypt(string encryptString)
        ...{
            byte[] keyBytes = Encoding.UTF8.GetBytes(key.Substring(0, 8));
            byte[] keyIV = keyBytes;
            byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
            DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, provider.CreateEncryptor(keyBytes, keyIV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Convert.ToBase64String(mStream.ToArray());
        }

        /**//// <summary>
        /// DES解密
        /// </summary>
        /// <param name="decryptString"></param>
        /// <returns></returns>
        public static string DesDecrypt(string decryptString)
        ...{
            byte[] keyBytes = Encoding.UTF8.GetBytes(key.Substring(0, 8));
            byte[] keyIV = keyBytes;
            byte[] inputByteArray = Convert.FromBase64String(decryptString);
            DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, provider.CreateDecryptor(keyBytes, keyIV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Encoding.UTF8.GetString(mStream.ToArray());
        }
    }
}