C#加密解密檔案小工具實現代碼

DebugLZQ在網上搜尋相關檔案加密的程式，發現給出的基本都是針對“字元創”、“文本”的加密與解密。對視頻檔案、圖片等一般檔案的加密解密程式少之又少，故寫下此文，實現一個對一般檔案進行加密的小工具。

　　程式的主要功能是：使用者通過檔案選擇框選擇要加密的檔案-》輸入密碼進行加密；選擇加密後的檔案，輸入密碼進行解密。

　　程式的主介面如下：

三個按鈕的Click事件處理常式如下： 複製代碼 代碼如下: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);//加密檔案
//刪除加密前的檔案
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);//解密檔案
//刪除解密前的檔案
File.Delete(inFile);
txtFileName.Text = string.Empty;
MessageBox.Show("解密成功");
}

加密解密的Help檔案源碼如下： 複製代碼 代碼如下: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>
/// 建立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>
/// 加密檔案隨機數產生
/// </summary>
private static RandomNumberGenerator rand = new RNGCryptoServiceProvider();
/// <summary>
/// 產生指定長度的隨機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>
/// 加密檔案
/// </summary>
/// <param name="inFile">待加密檔案</param>
/// <param name="outFile">加密後輸入檔案</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; // 輸入檔案長度
int size = (int)lSize;
byte[] bytes = new byte[BUFFER_SIZE]; // 緩衝
int read = -1; // 輸入檔案讀取數量
int value = 0;
// 擷取IV和salt
byte[] IV = GenerateRandomBytes(16);
byte[] salt = GenerateRandomBytes(16);
// 建立加密對象
SymmetricAlgorithm sma = DESFileClass.CreateRijndael(password, salt);
sma.IV = IV;
// 在輸出檔案開始部分寫入IV和salt
fout.Write(IV, 0, IV.Length);
fout.Write(salt, 0, salt.Length);
// 建立散列加密
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);
// 讀寫位元組塊到加密流緩衝區
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;
// 輸入檔案寫入散列
cout.Write(hash, 0, hash.Length);
// 關閉檔案流
cout.Flush();
cout.Close();
}
}
}
/// <summary>
/// 解密檔案
/// </summary>
/// <param name="inFile">待解密檔案</param>
/// <param name="outFile">解密後輸出檔案</param>
/// <param name="password">解密密碼</param>
public static void DecryptFile(string inFile, string outFile, string password)
{
// 建立開啟檔案流
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;
// 建立散列對象, 校正檔案
HashAlgorithm hasher = SHA256.Create();
using (CryptoStream cin = new CryptoStream(fin, sma.CreateDecryptor(), CryptoStreamMode.Read),
chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
{
// 讀取檔案長度
BinaryReader br = new BinaryReader(cin);
lSize = br.ReadInt64();
ulong tag = br.ReadUInt64();
if (FC_TAG != tag)
throw new CryptoHelpException("檔案被破壞");
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;
// 擷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("檔案被破壞");
}
if (outValue != lSize)
throw new CryptoHelpException("檔案大小不匹配");
}
}
}
}

加密/解密結果：
以加密D盤下的1.avi為例，加密後的檔案為1.avi.dat，即使重新命名回1.avi檔案依然無法開啟（檔案被加密）。

輸入密碼進行解密後，檔案恢複解密，可以順利開啟~