前面一篇博文中，分享了一個文件夾加密小工具，該工具是操作文件夾名稱的方法實現文件夾的一般加密，文件夾中的文件（視頻、圖片等）都原封不動的保存在那里。
DebugLZQ在網上搜索相關文件加密的程序，發現給出的基本都是針對“字符創”、“文本”的加密與解密。對視頻文件、圖片等一般文件的加密解密程序少之又少，故寫下此文，實現一個對一般文件進行加密的小工具。
程序的主要功能是：用戶通過文件選擇框選擇要加密的文件-》輸入密碼進行加密；選擇加密后的文件，輸入密碼進行解密。
程序的主界面如下：
三個按鈕的Click事件處理程序如下：
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 //刪除加密前的文件 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 //刪除解密前的文件 File.Delete(inFile); txtFileName.Text = string.Empty; MessageBox.Show("解密成功"); }
加密解密的Help文件源碼如下：
using System; using System.Collections.Generic; using System.Text; using System.Security.Cryptography; using System.IO; namespace DESFile { /// <summary> /// 異常處理類 /// </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> /// 檢驗兩個Byte數組是否相同 /// </summary> /// <param name="b1">Byte數組</param> /// <param name="b2">Byte數組</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> /// 創建DebugLZQ ,http://www.cnblogs.com/DebugLZQ /// </summary> /// <param name="password">密碼</param> /// <param name="salt"></param> /// <returns>加密對象</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> /// 加密文件隨機數生成 /// </summary> private static RandomNumberGenerator rand = new RNGCryptoServiceProvider(); /// <summary> /// 生成指定長度的隨機Byte數組 /// </summary> /// <param name="count">Byte數組長度</param> /// <returns>隨機Byte數組</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">加密后輸入文件</param> /// <param name="password">加密密碼</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; // 輸入文件長度 int size = (int)lSize; byte[] bytes = new byte[BUFFER_SIZE]; // 緩存 int read = -1; // 輸入文件讀取數量 int value = 0; // 獲取IV和salt byte[] IV = GenerateRandomBytes(16); byte[] salt = GenerateRandomBytes(16); // 創建加密對象 SymmetricAlgorithm sma = DESFileClass.CreateRijndael(password, salt); sma.IV = IV; // 在輸出文件開始部分寫入IV和salt fout.Write(IV, 0, IV.Length); fout.Write(salt, 0, salt.Length); // 創建散列加密 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); // 讀寫字節塊到加密流緩沖區 while ((read = fin.Read(bytes, 0, bytes.Length)) != 0) { cout.Write(bytes, 0, read); chash.Write(bytes, 0, read); value += read; } // 關閉加密流 chash.Flush(); chash.Close(); // 讀取散列 byte[] hash = hasher.Hash; // 輸入文件寫入散列 cout.Write(hash, 0, hash.Length); // 關閉文件流 cout.Flush(); cout.Close(); } } } /// <summary> /// 解密文件 /// </summary> /// <param name="inFile">待解密文件</param> /// <param name="outFile">解密后輸出文件</param> /// <param name="password">解密密碼</param> public static void DecryptFile(string inFile, string outFile, string password) { // 創建打開文件流 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; // 創建散列對象, 校驗文件 HashAlgorithm hasher = SHA256.Create(); using (CryptoStream cin = new CryptoStream(fin, sma.CreateDecryptor(), CryptoStreamMode.Read), chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write)) { // 讀取文件長度 BinaryReader br = new BinaryReader(cin); lSize = br.ReadInt64(); ulong tag = br.ReadUInt64(); if (FC_TAG != tag) throw new CryptoHelpException("文件被破壞"); 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; // 獲取比較和舊的散列對象 byte[] oldHash = new byte[hasher.HashSize / 8]; read = cin.Read(oldHash, 0, oldHash.Length); if ((oldHash.Length != read) || (!CheckByteArrays(oldHash, curHash))) throw new CryptoHelpException("文件被破壞"); } if (outValue != lSize) throw new CryptoHelpException("文件大小不匹配"); } } } }
加密/解密結果：
以加密D盤下的1.avi為例，加密后的文件為1.avi.dat，即使重命名回1.avi文件依然無法打開（文件被加密）。
輸入密碼進行解密后，文件恢復解密，可以順利打開~
