用C#实现DES加密解密

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: 在此处添加构造函数逻辑
            //
        }

        private static string key = "zhoufoxcn";

        /**/
        /// <summary>
        /// 对称加密解密的密钥
        /// </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));//必须8位的
            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));//必须8位的
            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());
        }
        static void Main(string[] args)
        {
            DESEncrypt.Key = "zhoufoxcn";
            string reStr =  DESEncrypt.DesEncrypt(DESEncrypt.Key);
            string reStr2 = DESEncrypt.DesDecrypt(reStr);
        }
    }
}

　　这样的key只能放入8位的