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// Crypto/RarAes.cpp
#include "StdAfx.h"
#include "RarAes.h"
#include "Sha1Cls.h"
namespace NCrypto {
namespace NRar3 {
CDecoder::CDecoder():
CAesCbcDecoder(kAesKeySize),
_thereIsSalt(false),
_needCalc(true),
_rar350Mode(false)
{
for (unsigned i = 0; i < sizeof(_salt); i++)
_salt[i] = 0;
}
HRESULT CDecoder::SetDecoderProperties2(const Byte *data, UInt32 size)
{
bool prev = _thereIsSalt;
_thereIsSalt = false;
if (size == 0)
{
if (!_needCalc && prev)
_needCalc = true;
return S_OK;
}
if (size < 8)
return E_INVALIDARG;
_thereIsSalt = true;
bool same = false;
if (_thereIsSalt == prev)
{
same = true;
if (_thereIsSalt)
{
for (unsigned i = 0; i < sizeof(_salt); i++)
if (_salt[i] != data[i])
{
same = false;
break;
}
}
}
for (unsigned i = 0; i < sizeof(_salt); i++)
_salt[i] = data[i];
if (!_needCalc && !same)
_needCalc = true;
return S_OK;
}
static const unsigned kPasswordLen_Bytes_MAX = 127 * 2;
void CDecoder::SetPassword(const Byte *data, unsigned size)
{
if (size > kPasswordLen_Bytes_MAX)
size = kPasswordLen_Bytes_MAX;
bool same = false;
if (size == _password.Size())
{
same = true;
for (UInt32 i = 0; i < size; i++)
if (data[i] != _password[i])
{
same = false;
break;
}
}
if (!_needCalc && !same)
_needCalc = true;
_password.CopyFrom(data, (size_t)size);
}
STDMETHODIMP CDecoder::Init()
{
CalcKey();
RINOK(SetKey(_key, kAesKeySize));
RINOK(SetInitVector(_iv, AES_BLOCK_SIZE));
return CAesCbcCoder::Init();
}
void CDecoder::CalcKey()
{
if (!_needCalc)
return;
const unsigned kSaltSize = 8;
Byte buf[kPasswordLen_Bytes_MAX + kSaltSize];
if (_password.Size() != 0)
memcpy(buf, _password, _password.Size());
size_t rawSize = _password.Size();
if (_thereIsSalt)
{
memcpy(buf + rawSize, _salt, kSaltSize);
rawSize += kSaltSize;
}
NSha1::CContext sha;
sha.Init();
Byte digest[NSha1::kDigestSize];
// rar reverts hash for sha.
const UInt32 kNumRounds = ((UInt32)1 << 18);
UInt32 i;
for (i = 0; i < kNumRounds; i++)
{
sha.UpdateRar(buf, rawSize, _rar350Mode);
Byte pswNum[3] = { (Byte)i, (Byte)(i >> 8), (Byte)(i >> 16) };
sha.UpdateRar(pswNum, 3, _rar350Mode);
if (i % (kNumRounds / 16) == 0)
{
NSha1::CContext shaTemp = sha;
shaTemp.Final(digest);
_iv[i / (kNumRounds / 16)] = (Byte)digest[4 * 4 + 3];
}
}
sha.Final(digest);
for (i = 0; i < 4; i++)
for (unsigned j = 0; j < 4; j++)
_key[i * 4 + j] = (digest[i * 4 + 3 - j]);
_needCalc = false;
}
}}
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