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/*
KeePass Password Safe - The Open-Source Password Manager
Copyright (C) 2003-2012 Dominik Reichl <dominik.reichl@t-online.de>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Security;
using System.Security.Cryptography;
using System.Diagnostics;
using KeePassLib.Resources;
namespace KeePassLib.Cryptography.Cipher
{
/// <summary>
/// Standard AES cipher implementation.
/// </summary>
public sealed class StandardAesEngine : ICipherEngine
{
private const CipherMode m_rCipherMode = CipherMode.CBC;
private const PaddingMode m_rCipherPadding = PaddingMode.PKCS7;
private static PwUuid m_uuidAes = null;
/// <summary>
/// UUID of the cipher engine. This ID uniquely identifies the
/// AES engine. Must not be used by other ciphers.
/// </summary>
public static PwUuid AesUuid
{
get
{
if(m_uuidAes == null)
{
m_uuidAes = new PwUuid(new byte[]{
0x31, 0xC1, 0xF2, 0xE6, 0xBF, 0x71, 0x43, 0x50,
0xBE, 0x58, 0x05, 0x21, 0x6A, 0xFC, 0x5A, 0xFF });
}
return m_uuidAes;
}
}
/// <summary>
/// Get the UUID of this cipher engine as <c>PwUuid</c> object.
/// </summary>
public PwUuid CipherUuid
{
get { return StandardAesEngine.AesUuid; }
}
/// <summary>
/// Get a displayable name describing this cipher engine.
/// </summary>
public string DisplayName { get { return KLRes.EncAlgorithmAes; } }
private static void ValidateArguments(Stream stream, bool bEncrypt, byte[] pbKey, byte[] pbIV)
{
Debug.Assert(stream != null); if(stream == null) throw new ArgumentNullException("stream");
Debug.Assert(pbKey != null); if(pbKey == null) throw new ArgumentNullException("pbKey");
Debug.Assert(pbKey.Length == 32);
if(pbKey.Length != 32) throw new ArgumentException("Key must be 256 bits wide!");
Debug.Assert(pbIV != null); if(pbIV == null) throw new ArgumentNullException("pbIV");
Debug.Assert(pbIV.Length == 16);
if(pbIV.Length != 16) throw new ArgumentException("Initialization vector must be 128 bits wide!");
if(bEncrypt)
{
Debug.Assert(stream.CanWrite);
if(stream.CanWrite == false) throw new ArgumentException("Stream must be writable!");
}
else // Decrypt
{
Debug.Assert(stream.CanRead);
if(stream.CanRead == false) throw new ArgumentException("Encrypted stream must be readable!");
}
}
private static Stream CreateStream(Stream s, bool bEncrypt, byte[] pbKey, byte[] pbIV)
{
StandardAesEngine.ValidateArguments(s, bEncrypt, pbKey, pbIV);
RijndaelManaged r = new RijndaelManaged();
if(r.BlockSize != 128) // AES block size
{
Debug.Assert(false);
r.BlockSize = 128;
}
byte[] pbLocalIV = new byte[16];
Array.Copy(pbIV, pbLocalIV, 16);
r.IV = pbLocalIV;
byte[] pbLocalKey = new byte[32];
Array.Copy(pbKey, pbLocalKey, 32);
r.KeySize = 256;
r.Key = pbLocalKey;
r.Mode = m_rCipherMode;
r.Padding = m_rCipherPadding;
ICryptoTransform iTransform = (bEncrypt ? r.CreateEncryptor() : r.CreateDecryptor());
Debug.Assert(iTransform != null);
if(iTransform == null) throw new SecurityException("Unable to create Rijndael transform!");
return new CryptoStream(s, iTransform, bEncrypt ? CryptoStreamMode.Write :
CryptoStreamMode.Read);
}
public Stream EncryptStream(Stream sPlainText, byte[] pbKey, byte[] pbIV)
{
return StandardAesEngine.CreateStream(sPlainText, true, pbKey, pbIV);
}
public Stream DecryptStream(Stream sEncrypted, byte[] pbKey, byte[] pbIV)
{
return StandardAesEngine.CreateStream(sEncrypted, false, pbKey, pbIV);
}
}
}
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