加密，解密

using System;

using System.Security.Cryptography;

using System.IO;

using System.Text;

using System.Globalization;





/// <summary> 

/// 对指定内容进行DES加密和解密处理     

/// </summary>     

public sealed class DESEncrypt

{

    /// <summary>     

    /// 对字符串进行DES加密  

    /// </summary>     

    /// <param name="sourcestring">待加密的字符串</param>  

    /// <param name="key">必须长度等于8的字符串</param>

    /// <param name="iv">必须长度大于等于8的字符串</param>

    /// <returns>加密后的BASE64编码的字符串</returns>     

    internal static string Encrypt(string src, string key, string iv)

    {

        byte[] byteKey = Encoding.Default.GetBytes(key);

        byte[] byteIv = Encoding.Default.GetBytes(iv);

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        using (MemoryStream ms = new MemoryStream())

        {



            try

            {

                byte[] data = Encoding.Default.GetBytes(src);

                using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(byteKey, byteIv), CryptoStreamMode.Write))

                {

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

                    cs.FlushFinalBlock();

                }

                return Convert.ToBase64String(ms.ToArray());

            }

            catch

            {

                throw;

            }

        }

    }



    /// <summary>  

    /// 对DES加密后的字符串进行解密     

    /// </summary>     

    /// <param name="encryptedString">待解密的字符串</param>     

    /// <param name="key">同加密时所采用的key</param>

    /// <param name="iv">同加密时所采用的iv</param>

    /// <returns>解密后的字符串</returns>     

    internal static string Decrypt(string src, string key, string iv)

    {

        byte[] byteKey = Encoding.Default.GetBytes(key);

        byte[] byteIv = Encoding.Default.GetBytes(iv);

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();



        using (MemoryStream ms = new MemoryStream())

        {

            try

            {

                byte[] data = Convert.FromBase64String(src);

                using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(byteKey, byteIv), CryptoStreamMode.Write))

                {

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

                    cs.FlushFinalBlock();

                }

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

            }

            catch

            {

                throw;

            }

        }

    }



    /// <summary>  

    /// 对文件内容进行DES加密     

    /// </summary>     

    /// <param name="sourceFile">待加密的文件绝对路径</param>     

    /// <param name="destFile">加密后的文件保存的绝对路径</param>   

    /// <param name="key">必须长度等于8的字符串</param>

    /// <param name="iv">必须长度大于等于8的字符串</param>

    internal static void EncryptFile(string sourceFile, string destFile, string key, string iv)

    {

        if (!File.Exists(sourceFile))

            throw new FileNotFoundException("指定的文件路径不存在！", sourceFile);



        byte[] byteKey = Encoding.Default.GetBytes(key);

        byte[] byteIV = Encoding.Default.GetBytes(iv);

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        byte[] byteFile = File.ReadAllBytes(sourceFile);



        using (FileStream fs = new FileStream(destFile, FileMode.Create, FileAccess.Write))

        {

            try

            {

                using (CryptoStream cs = new CryptoStream(fs, des.CreateEncryptor(byteKey, byteIV), CryptoStreamMode.Write))

                {

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

                    cs.FlushFinalBlock();

                }

            }

            catch

            {

                throw;

            }



            finally

            {

                fs.Close();

            }

        }

    }



    /// <summary>     

    /// Encrypts the file.     

    /// 对文件内容进行DES加密，加密后覆盖掉原来的文件     

    /// </summary>     

    /// <param name="sourceFile">The source file.待加密的文件的绝对路径</param>     

    /// <param name="key">必须长度等于8的字符串</param>

    /// <param name="iv">必须长度大于等于8的字符串</param>

    internal static void EncryptFile(string sourceFile, string key, string iv)

    {

        EncryptFile(sourceFile, sourceFile, key, iv);

    }



    /// <summary> 

    /// 对文件内容进行DES解密     

    /// </summary>     

    /// <param name="sourceFile">待解密的文件绝对路径</param>     

    /// <param name="destFile">解密后的文件保存的绝对路径</param>

    /// <param name="key">同加密时所采用的key</param>

    /// <param name="iv">同加密时所采用的iv</param>

    internal static void DecryptFile(string sourceFile, string destFile, string key, string iv)

    {

        if (!File.Exists(sourceFile)) throw new FileNotFoundException("指定的文件路径不存在！", sourceFile);

        byte[] byteKey = Encoding.Default.GetBytes(key);

        byte[] byteIV = Encoding.Default.GetBytes(iv);

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        byte[] byteFile = File.ReadAllBytes(sourceFile);



        using (FileStream fs = new FileStream(destFile, FileMode.Create, FileAccess.Write))

        {

            try

            {

                using (CryptoStream cs = new CryptoStream(fs, des.CreateDecryptor(byteKey, byteIV), CryptoStreamMode.Write))

                {

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

                    cs.FlushFinalBlock();

                }

            }

            catch

            {

                throw;

            }

            finally

            {

                fs.Close();

            }

        }

    }



    /// <summary> 

    /// 对文件内容进行DES解密，加密后覆盖掉原来的文件     

    /// </summary>     

    /// <param name="sourceFile">待解密的文件的绝对路径</param>     

    /// <param name="key">同加密时所采用的key</param>

    /// <param name="iv">同加密时所采用的iv</param>

    internal static void DecryptFile(string sourceFile, string key, string iv)

    {

        DecryptFile(sourceFile, sourceFile, key, iv);

    }

}