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// RarAES.cpp
// Note: you must include Crypto/AES/MyAES.cpp to project to initialize AES tables
#include "StdAfx.h"
#include "RarAES.h"
#include "../../Common/MethodId.h"
#include "../Hash/Sha1.h"
namespace NCrypto {
namespace NRar29 {
CDecoder::CDecoder():
_thereIsSalt(false),
_needCalculate(true),
_rar350Mode(false)
{
for (int i = 0; i < sizeof(_salt); i++)
_salt[i] = 0;
}
STDMETHODIMP CDecoder::SetDecoderProperties2(const Byte *data, UInt32 size)
{
bool thereIsSaltPrev = _thereIsSalt;
_thereIsSalt = false;
if (size == 0)
return S_OK;
if (size < 8)
return E_INVALIDARG;
_thereIsSalt = true;
bool same = false;
if (_thereIsSalt == thereIsSaltPrev)
{
same = true;
if (_thereIsSalt)
{
for (int i = 0; i < sizeof(_salt); i++)
if (_salt[i] != data[i])
{
same = false;
break;
}
}
}
for (int i = 0; i < sizeof(_salt); i++)
_salt[i] = data[i];
if (!_needCalculate && !same)
_needCalculate = true;
return S_OK;
}
static const int kMaxPasswordLength = 127 * 2;
STDMETHODIMP CDecoder::CryptoSetPassword(const Byte *data, UInt32 size)
{
if (size > kMaxPasswordLength)
size = kMaxPasswordLength;
bool same = false;
if (size == buffer.GetCapacity())
{
same = true;
for (UInt32 i = 0; i < size; i++)
if (data[i] != buffer[i])
{
same = false;
break;
}
}
if (!_needCalculate && !same)
_needCalculate = true;
buffer.SetCapacity(size);
memcpy(buffer, data, size);
return S_OK;
}
STDMETHODIMP CDecoder::Init()
{
Calculate();
AesSetKeyDecode(&Aes.aes, aesKey, kRarAesKeySize);
AesCbcInit(&Aes, aesInit);
return S_OK;
}
STDMETHODIMP_(UInt32) CDecoder::Filter(Byte *data, UInt32 size)
{
return AesCbcDecode(&Aes, data, size);
}
void CDecoder::Calculate()
{
if (_needCalculate)
{
const int kSaltSize = 8;
Byte rawPassword[kMaxPasswordLength + kSaltSize];
memcpy(rawPassword, buffer, buffer.GetCapacity());
size_t rawLength = buffer.GetCapacity();
if (_thereIsSalt)
{
memcpy(rawPassword + rawLength, _salt, kSaltSize);
rawLength += kSaltSize;
}
NSha1::CContext sha;
sha.Init();
// seems rar reverts hash for sha.
const int hashRounds = 0x40000;
int i;
for (i = 0; i < hashRounds; i++)
{
sha.Update(rawPassword, rawLength, _rar350Mode);
Byte pswNum[3] = { (Byte)i, (Byte)(i >> 8), (Byte)(i >> 16) };
sha.Update(pswNum, 3, _rar350Mode);
if (i % (hashRounds / 16) == 0)
{
NSha1::CContext shaTemp = sha;
Byte digest[NSha1::kDigestSize];
shaTemp.Final(digest);
aesInit[i / (hashRounds / 16)] = (Byte)digest[4 * 4 + 3];
}
}
/*
// it's test message for sha
const char *message = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
sha.Update((const Byte *)message, strlen(message));
*/
Byte digest[20];
sha.Final(digest);
for (i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
aesKey[i * 4 + j] = (digest[i * 4 + 3 - j]);
}
_needCalculate = false;
}
}}
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