Windows中使用C#为文件夹和文件编写密码锁的示例分享

    private void btnBrowseFolder_Click(object sender, EventArgs e)
    {
      
      status = lockType;//
      

      if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
      {
        DirectoryInfo d = new DirectoryInfo(folderBrowserDialog1.SelectedPath);
        string selectedpath = d.Parent.FullName + d.Name;
        if (folderBrowserDialog1.SelectedPath.LastIndexOf(".{") == -1)//通过文件夹名称，判断加密
        {          
          SetPwd(folderBrowserDialog1.SelectedPath);
          if (!d.Root.Equals(d.Parent.FullName))
          {            
              d.MoveTo(d.Parent.FullName + "\\" + d.Name + status);//文件夹重命名
          }
          else d.MoveTo(d.Parent.FullName + d.Name + status);
          txtFolderPath.Text = folderBrowserDialog1.SelectedPath;
          
        }
        else//解密文件夹
        {
          status = GetStatus(status);
          bool s = CheckPwd();
          if (s)
          {
            File.Delete(folderBrowserDialog1.SelectedPath + "\\key.xml");
            string path = folderBrowserDialog1.SelectedPath.Substring(0, folderBrowserDialog1.SelectedPath.LastIndexOf("."));
            d.MoveTo(path);
            txtFolderPath.Text = path;
            
          }
        }
      }
    }

    private void btnSelectFile_Click(object sender, EventArgs e)
    {
      if (openFileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK)
      {
        txtFileName.Text = openFileDialog1.FileName ;
      }
    }

    private void btnEncryptFile_Click(object sender, EventArgs e)
    {
      string inFile=txtFileName.Text;
      string outFile = inFile + ".dat";
      string password=txtPassword.Text ;
      DESFile.DESFileClass.EncryptFile(inFile, outFile, password);//加密文件
      //删除加密前的文件
      File.Delete(inFile);
      txtFileName.Text = string.Empty;
      MessageBox.Show("加密成功");
    }

    private void btnDecryptFile_Click(object sender, EventArgs e)
    {
      string inFile = txtFileName.Text;
      string outFile = inFile.Substring(0,inFile.Length - 4);
      string password = txtPassword.Text;
      DESFile.DESFileClass.DecryptFile (inFile, outFile, password);//解密文件
      //删除解密前的文件
      File.Delete(inFile);
      txtFileName.Text = string.Empty;
      MessageBox.Show("解密成功");
    }

加密解密的Help文件源码如下：

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

namespace DESFile
{
  /// <summary>
  /// 异常处理类
  /// </summary>
  public class CryptoHelpException : ApplicationException
  {
    public CryptoHelpException(string msg) : base(msg) { }
  }

  /// <summary>
  /// CryptHelp
  /// </summary>
  public class DESFileClass
  {
    private const ulong FC_TAG = 0xFC010203040506CF;

    private const int BUFFER_SIZE = 128 * 1024;

    /// <summary>
    /// 检验两个Byte数组是否相同
    /// </summary>
    /// <param name="b1">Byte数组</param>
    /// <param name="b2">Byte数组</param>
    /// <returns>true－相等</returns>
    private static bool CheckByteArrays(byte[] b1, byte[] b2)
    {
      if (b1.Length == b2.Length)
      {
        for (int i = 0; i < b1.Length; ++i)
        {
          if (b1[i] != b2[i])
            return false;
        }
        return true;
      }
      return false;
    }

    /// <summary>
    /// 创建DebugLZQ ,http://www.cnblogs.com/DebugLZQ
    /// </summary>
    /// <param name="password">密码</param>
    /// <param name="salt"></param>
    /// <returns>加密对象</returns>
    private static SymmetricAlgorithm CreateRijndael(string password, byte[] salt)
    {
      PasswordDeriveBytes pdb = new PasswordDeriveBytes(password, salt, "SHA256", 1000);

      SymmetricAlgorithm sma = Rijndael.Create();
      sma.KeySize = 256;
      sma.Key = pdb.GetBytes(32);
      sma.Padding = PaddingMode.PKCS7;
      return sma;
    }

    /// <summary>
    /// 加密文件随机数生成
    /// </summary>
    private static RandomNumberGenerator rand = new RNGCryptoServiceProvider();

    /// <summary>
    /// 生成指定长度的随机Byte数组
    /// </summary>
    /// <param name="count">Byte数组长度</param>
    /// <returns>随机Byte数组</returns>
    private static byte[] GenerateRandomBytes(int count)
    {
      byte[] bytes = new byte[count];
      rand.GetBytes(bytes);
      return bytes;
    }

    /// <summary>
    /// 加密文件
    /// </summary>
    /// <param name="inFile">待加密文件</param>
    /// <param name="outFile">加密后输入文件</param>
    /// <param name="password">加密密码</param>
    public static void EncryptFile(string inFile, string outFile, string password)
    {
      using (FileStream fin = File.OpenRead(inFile),
        fout = File.OpenWrite(outFile))
      {
        long lSize = fin.Length; // 输入文件长度
        int size = (int)lSize;
        byte[] bytes = new byte[BUFFER_SIZE]; // 缓存
        int read = -1; // 输入文件读取数量
        int value = 0;

        // 获取IV和salt
        byte[] IV = GenerateRandomBytes(16);
        byte[] salt = GenerateRandomBytes(16);

        // 创建加密对象
        SymmetricAlgorithm sma = DESFileClass.CreateRijndael(password, salt);
        sma.IV = IV;

        // 在输出文件开始部分写入IV和salt
        fout.Write(IV, 0, IV.Length);
        fout.Write(salt, 0, salt.Length);

        // 创建散列加密
        HashAlgorithm hasher = SHA256.Create();
        using (CryptoStream cout = new CryptoStream(fout, sma.CreateEncryptor(), CryptoStreamMode.Write),
          chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
        {
          BinaryWriter bw = new BinaryWriter(cout);
          bw.Write(lSize);

          bw.Write(FC_TAG);

          // 读写字节块到加密流缓冲区
          while ((read = fin.Read(bytes, 0, bytes.Length)) != 0)
          {
            cout.Write(bytes, 0, read);
            chash.Write(bytes, 0, read);
            value += read;
          }
          // 关闭加密流
          chash.Flush();
          chash.Close();

          // 读取散列
          byte[] hash = hasher.Hash;

          // 输入文件写入散列
          cout.Write(hash, 0, hash.Length);

          // 关闭文件流
          cout.Flush();
          cout.Close();
        }
      }
    }

    /// <summary>
    /// 解密文件
    /// </summary>
    /// <param name="inFile">待解密文件</param>
    /// <param name="outFile">解密后输出文件</param>
    /// <param name="password">解密密码</param>
    public static void DecryptFile(string inFile, string outFile, string password)
    {
      // 创建打开文件流
      using (FileStream fin = File.OpenRead(inFile),
        fout = File.OpenWrite(outFile))
      {
        int size = (int)fin.Length;
        byte[] bytes = new byte[BUFFER_SIZE];
        int read = -1;
        int value = 0;
        int outValue = 0;

        byte[] IV = new byte[16];
        fin.Read(IV, 0, 16);
        byte[] salt = new byte[16];
        fin.Read(salt, 0, 16);

        SymmetricAlgorithm sma = DESFileClass.CreateRijndael(password, salt);
        sma.IV = IV;

        value = 32;
        long lSize = -1;

        // 创建散列对象, 校验文件
        HashAlgorithm hasher = SHA256.Create();

        using (CryptoStream cin = new CryptoStream(fin, sma.CreateDecryptor(), CryptoStreamMode.Read),
          chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
        {
          // 读取文件长度
          BinaryReader br = new BinaryReader(cin);
          lSize = br.ReadInt64();
          ulong tag = br.ReadUInt64();

          if (FC_TAG != tag)
            throw new CryptoHelpException("文件被破坏");

          long numReads = lSize / BUFFER_SIZE;

          long slack = (long)lSize % BUFFER_SIZE;

          for (int i = 0; i < numReads; ++i)
          {
            read = cin.Read(bytes, 0, bytes.Length);
            fout.Write(bytes, 0, read);
            chash.Write(bytes, 0, read);
            value += read;
            outValue += read;
          }

          if (slack > 0)
          {
            read = cin.Read(bytes, 0, (int)slack);
            fout.Write(bytes, 0, read);
            chash.Write(bytes, 0, read);
            value += read;
            outValue += read;
          }

          chash.Flush();
          chash.Close();

          fout.Flush();
          fout.Close();

          byte[] curHash = hasher.Hash;

          // 获取比较和旧的散列对象
          byte[] oldHash = new byte[hasher.HashSize / 8];
          read = cin.Read(oldHash, 0, oldHash.Length);
          if ((oldHash.Length != read) || (!CheckByteArrays(oldHash, curHash)))
            throw new CryptoHelpException("文件被破坏");
        }

        if (outValue != lSize)
          throw new CryptoHelpException("文件大小不匹配");
      }
    }
  }
}