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");}

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saltbyte[] 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saltfout.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");}}}
}