DES加密解密

自己写的DES加密解密类，加密后生成Base64字符串，并去除'='字符。

加密后替换掉'+'，这样加密后的字符串可以作为url参数传递。

using System;

using System.IO;

using System.Security.Cryptography;

using System.Text;



namespace QuaEdu.Helper

{

    /// <summary>

    /// DES加密/解密类。

    /// 2014年3月15日

    /// </summary>

    public class DESHelper

    {

        #region 默认密钥

        /// <summary>

        /// 默认密钥

        /// </summary>

        private static readonly string m_key = "simpo_s0611163";

        #endregion



        #region ========加密========

        /// <summary> 

        /// 加密数据 

        /// </summary> 

        /// <param name="Text">原文</param> 

        /// <returns>密文</returns> 

        public static string Encrypt(string Text)

        {

            return Encrypt(Text, m_key);

        }



        /// <summary> 

        /// 加密数据 

        /// </summary> 

        /// <param name="Text">原文</param> 

        /// <param name="sKey">密钥</param> 

        /// <returns>密文</returns> 

        public static string Encrypt(string Text, string sKey)

        {

            DESCryptoServiceProvider desKey = new DESCryptoServiceProvider();



            byte[] inputByteArray = Encoding.Default.GetBytes(Text);

            byte[] keyByteArray = Encoding.Default.GetBytes(sKey);



            MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();

            md5.ComputeHash(keyByteArray);



            desKey.Key = HalveByteArray(md5.Hash);

            desKey.IV = HalveByteArray(md5.Hash);



            MemoryStream ms = new MemoryStream();

            CryptoStream cs = new CryptoStream(ms, desKey.CreateEncryptor(), CryptoStreamMode.Write);



            cs.Write(inputByteArray, 0, inputByteArray.Length);

            cs.FlushFinalBlock();



            return Convert.ToBase64String(ms.ToArray()).Replace("=", "").Replace("+", "-").Replace("/", "*");

        }

        #endregion



        #region ========解密========

        /// <summary> 

        /// 解密数据 

        /// </summary> 

        /// <param name="Text">密文</param> 

        /// <returns>原文</returns> 

        public static string Decrypt(string Text)

        {

            return Decrypt(Text, m_key);

        }



        /// <summary> 

        /// 解密数据 

        /// </summary> 

        /// <param name="Text">密文</param> 

        /// <param name="sKey">密钥</param> 

        /// <returns>原文</returns> 

        public static string Decrypt(string Text, string sKey)

        {

            StringBuilder sb = new StringBuilder();

            if (Text.Length % 4 != 0)

            {

                for (int i = 0; i < 4 - Text.Length % 4; i++)

                {

                    sb.Append("=");

                }

            }

            Text = Text.Replace("-", "+").Replace("*", "/") + sb.ToString();



            DESCryptoServiceProvider desKey = new DESCryptoServiceProvider();



            byte[] inputByteArray = Convert.FromBase64String(Text);

            byte[] keyByteArray = Encoding.Default.GetBytes(sKey);



            MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();

            md5.ComputeHash(keyByteArray);



            desKey.Key = HalveByteArray(md5.Hash);

            desKey.IV = HalveByteArray(md5.Hash);



            MemoryStream ms = new MemoryStream();

            CryptoStream cs = new CryptoStream(ms, desKey.CreateDecryptor(), CryptoStreamMode.Write);



            cs.Write(inputByteArray, 0, inputByteArray.Length);

            cs.FlushFinalBlock();



            return Encoding.Default.GetString(ms.ToArray());

        }

        #endregion



        #region 把字节数组缩短一半

        /// <summary>

        /// 把字节数组缩短一半

        /// </summary>

        private static byte[] HalveByteArray(byte[] data)

        {

            byte[] result = new byte[data.Length / 2];



            for (int i = 0; i < result.Length; i++)

            {

                int x = (data[i * 2] + data[i * 2 + 1]) / 2;

                result[i] = (byte)x;

            }



            return result;

        }

        #endregion



    }

}

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