Encrypt / Decrypt

tuldok89

Dec 16th, 2013

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using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.Security;
using System.IO;
namespace Tuldok
{
public enum Algorithm
{
AES,
DES,
RC2,
TripleDES,
}
public class Encryptor
{
SymmetricAlgorithm m_cipher;
Algorithm m_algorithm;
const int c_bufferSize = 4096;
/// <summary>
/// Constructor
/// </summary>
/// <param name="algorithm">The cipher to use</param>
public Encryptor(Algorithm algorithm)
{
m_algorithm = algorithm;
switch (algorithm)
{
case Algorithm.AES:
m_cipher = new AesCryptoServiceProvider();
break;
case Algorithm.DES:
m_cipher = new DESCryptoServiceProvider();
break;
case Algorithm.RC2:
m_cipher = new RC2CryptoServiceProvider();
break;
case Algorithm.TripleDES:
m_cipher = new TripleDESCryptoServiceProvider();
break;
}
m_cipher.Mode = CipherMode.CBC;
}
/// <summary>
/// Default constructor. Will use AES.
/// </summary>
public Encryptor()
{
m_cipher = new AesCryptoServiceProvider();
m_algorithm = Algorithm.AES;
}
~Encryptor()
{
m_cipher = null;
}
/// <summary>
/// Encrypt a file
/// </summary>
/// <param name="inStrFilename">Input filename</param>
/// <param name="outStrFilename">Output filename</param>
/// <param name="password">Password</param>
public void EncryptFile(string inStrFilename, string outStrFilename, string password)
{
m_cipher.GenerateIV(); // generate a random initialization vector
m_cipher.Padding = PaddingMode.None;
var keygen = new Rfc2898DeriveBytes(password, m_cipher.IV);
var key = keygen.GetBytes(m_cipher.KeySize / 8); // derive a key from the password
m_cipher.Key = key;
var inFile = new FileStream(inStrFilename, FileMode.Open);
var outFile = new FileStream(outStrFilename, FileMode.Create);
var in_buffer = new byte[c_bufferSize];
var out_buffer = new byte[c_bufferSize];
int bytesRead;
var cryptor = m_cipher.CreateEncryptor();
outFile.WriteByte((byte)m_algorithm); // write the algorithm used to stream
outFile.Write(m_cipher.IV, 0, m_cipher.IV.GetLength(0)); // write the initialization vector to stream
for(;;)
{
bytesRead = inFile.Read(in_buffer, 0, c_bufferSize);
if (bytesRead == c_bufferSize)
{
cryptor.TransformBlock(in_buffer, 0, bytesRead, out_buffer, 0);
outFile.Write(out_buffer, 0, c_bufferSize);
}
else
{
var bytes = cryptor.TransformFinalBlock(in_buffer, 0, bytesRead);
outFile.Write(bytes, 0, bytes.GetLength(0));
}
if (bytesRead < 4096)
break;
}
outFile.Flush();
outFile.Close();
inFile.Close();
outFile = null;
inFile = null;
}
}
public class Decryptor
{
const int c_bufferSize = 4096;
public Decryptor()
{
}
/// <summary>
/// Decrypt file
/// </summary>
/// <param name="inStrFileName"></param>
/// <param name="outStrFileName"></param>
/// <param name="password"></param>
public void DecryptFile(string inStrFileName, string outStrFileName, string password)
{
var inFile = new FileStream(inStrFileName, FileMode.Open);
var outFile = new FileStream(outStrFileName, FileMode.Create);
var in_buffer = new byte[c_bufferSize];
var out_buffer = new byte[c_bufferSize];
int bytesRead;
var algorithm = (Algorithm)inFile.ReadByte();
SymmetricAlgorithm cipher;
switch (algorithm)
{
case Algorithm.DES:
cipher = new DESCryptoServiceProvider();
break;
case Algorithm.RC2:
cipher = new RC2CryptoServiceProvider();
break;
case Algorithm.TripleDES:
cipher = new TripleDESCryptoServiceProvider();
break;
default:
cipher = new AesCryptoServiceProvider();
break;
}
var saltSize = cipher.IV.GetLength(0);
var salt = new byte[saltSize];
inFile.Read(salt, 0, saltSize); // get the initialization vector from stream
cipher.IV = salt;
cipher.Mode = CipherMode.CBC;
cipher.Padding = PaddingMode.None;
var keygen = new Rfc2898DeriveBytes(password, salt);
var key = keygen.GetBytes(cipher.KeySize / 8); // create key
cipher.Key = key;
var decryptor = cipher.CreateDecryptor();
for(;;)
{
bytesRead = inFile.Read(in_buffer, 0, c_bufferSize);
if (bytesRead == c_bufferSize)
{
decryptor.TransformBlock(in_buffer, 0, c_bufferSize, out_buffer, 0);
outFile.Write(out_buffer, 0, c_bufferSize);
}
else
{
var bytes = decryptor.TransformFinalBlock(in_buffer, 0, bytesRead);
outFile.Write(bytes, 0, bytes.GetLength(0));
}
if (bytesRead < 4096)
break;
}
outFile.Flush();
outFile.Close();
inFile.Close();
outFile = null;
inFile = null;
}
}
}

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