使用C#實現文件加密、解密
使用C#簡單實現了文件加密、解密功能，文章配圖Ransomware，是因為Ransomware基本也是使用類似思路。
- 代碼是在.Net Framework 4.0環境下實現；
- 主要使用了庫System.Security.Cryptography，使用的演算法是對稱加密演算法SHA256、密鑰長度256；加鹽（Salt），Salt隨機生成；
- 使用語法：Encryptor.exe 加密口令 源目錄 加密後目錄 ； 示例：Encryptor.exe password C: C:Encrypted
附錄-詳細代碼：
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Collections;
using System.ComponentModel;
using System.Data;
using system.Net;
using System.Net.Sockets;
using System.Threading;
using System.IO;
using System.Security.Cryptography;
using System.DirectoryServices;
namespace Encryptor
{
class Program
{
private const ulong FC_TAG = 0xFC010203040506CF;
private const int BUFFER_SIZE = 128 * 1024;
private static RandomNumberGenerator rand = new RNGCryptoServiceProvider();
static void Main(string[] args)
{
if (args.Length == 3)
{
string password = args[0].ToString().Trim();
string SourcePath = args[1].ToString().Trim();
string DestinationPath = args[2].ToString().Trim();
string strTmp = DestinationPath.Substring(DestinationPath.Length - 1);
if (!(strTmp == @""))
DestinationPath += @"";
Console.WriteLine("Encryption Begin...");
try
{
DirectoryInfo sourceDir = new DirectoryInfo(SourcePath);
foreach (FileInfo f in sourceDir.GetFiles())
{
EncryptFile(f.FullName, DestinationPath+f.Name+@".encrypt", password);
}
Console.WriteLine("Encryption Success");
}
catch (Exception e)
{
Console.WriteLine("Encryption Failed: " + e.ToString());
}
}
}
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;
}
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;
}
private static byte[] GenerateRandomBytes(int count)
{
byte[] bytes = new byte[count];
rand.GetBytes(bytes);
return bytes;
}
public static void EncryptFile(string inFile, string outFile, string password)
{
using (FileStream fin = File.OpenRead(inFile), fout = File.OpenWrite(outFile))
{
long lSize = fin.Length;
int size = (int)lSize;
byte[] bytes = new byte[BUFFER_SIZE];
int read = -1;
int value = 0;
byte[] IV = GenerateRandomBytes(16);
byte[] salt = GenerateRandomBytes(16);
SymmetricAlgorithm sma = CreateRijndael(password, salt);
sma.IV = IV;
fout.Write(IV, 0, IV.Length);
fout.Write(salt, 0, salt.Length);
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);
while ((read = fin.Read(bytes, 0, bytes.Length)) != 0)
{
cout.Write(bytes, 0, read);
chash.Write(bytes, 0, read);
value += read;
}
chash.Flush();
chash.Close();
byte[] hash = hasher.Hash;
cout.Write(hash, 0, hash.Length);
cout.Flush();
cout.Close();
}
}
}
public static void DecryptFile(string inFile, string outFile, string password)
{
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;
HashAlgorithm hasher = SHA256.Create();
using (CryptoStream cin = new CryptoStream(fin, sma.CreateDecryptor(), CryptoStreamMode.Read), chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
{
BinaryReader br = new BinaryReader(cin);
lSize = br.ReadInt64();
ulong tag = br.ReadUInt64();
if (FC_TAG != tag)
{
throw new CryptographicException("文件已被破壞！");
}
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;
byte[] oldHash = new byte[hasher.HashSize / 8];
read = cin.Read(oldHash, 0, oldHash.Length);
if ((oldHash.Length != read) || (!CheckByteArrays(oldHash, curHash)))
throw new CryptographicException("文件已被破壞！");
}
if (outvalue != lSize)
throw new CryptographicException("文件大小不匹配！");
}
}
}
}
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