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");
}
}
}
}
