对文件加密解密算法设计

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Security.Cryptography;
using System.IO;


namespace 加密解密
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 异常处理类
        /// </summary>
        public class CryptoHelpException : ApplicationException
        {
            public CryptoHelpException(string msg) : base(msg) { }
        }

        /// <summary>
        /// CryptHelp
        /// </summary>
     
            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  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  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  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  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  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 = 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  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 =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");
                }
            }
      

        private void button1_Click(object sender, EventArgs e)
        {
            FolderBrowserDialog dialog = new FolderBrowserDialog();
            dialog.Description = "请选择存储路径";
            if (dialog.ShowDialog() == DialogResult.OK)
            {
                wjj.Text = dialog.SelectedPath;
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if (wjj.Text == "")
            {
                MessageBox.Show("请选择文件夹!");
            }
            else
            {
                DirectoryInfo dir = new DirectoryInfo(wjj.Text);
                FileInfo[] allFile = dir.GetFiles();
                if (!Directory.Exists(wjj.Text + "/加密"))
                {
                    Directory.CreateDirectory(wjj.Text + "/加密");
                }
                foreach (FileInfo file in allFile)
                {

                    string inFile = wjj.Text + "/" + file.Name;
                   
                    string outFile = wjj.Text + "/加密/" + file.Name; ;
                    string password = txtPassword.Text;
                    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 button3_Click(object sender, EventArgs e)
        {
            if (wjj.Text == "") {
                MessageBox.Show("请选择文件夹!");
            }
            else
            {
                DirectoryInfo dir = new DirectoryInfo(wjj.Text);
                FileInfo[] allFile = dir.GetFiles();
                if (!Directory.Exists(wjj.Text + "/解密"))
                {
                    Directory.CreateDirectory(wjj.Text + "/解密");
                }
                foreach (FileInfo file in allFile)
                {
                    string inFile = wjj.Text + "/" + file.Name;
                    string outFile = wjj.Text + "/解密/" + file.Name; ;
                    string password = txtPassword.Text;
                    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");
            }
        }
    }
}