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// Crypto/ZipStrong.cpp
#include "StdAfx.h"
#include "../../../C/7zCrc.h"
#include "../../../C/CpuArch.h"
#include "../Common/StreamUtils.h"
#include "MyAes.h"
#include "Sha1.h"
#include "ZipStrong.h"
namespace NCrypto {
namespace NZipStrong {
static const UInt16 kAES128 = 0x660E;
// DeriveKey* function is similar to CryptDeriveKey() from Windows.
// But MSDN tells that we need such scheme only if
// "the required key length is longer than the hash value"
// but ZipStrong uses it always.
static void DeriveKey2(const Byte *digest, Byte c, Byte *dest)
{
Byte buf[64];
memset(buf, c, 64);
for (unsigned i = 0; i < NSha1::kDigestSize; i++)
buf[i] ^= digest[i];
NSha1::CContext sha;
sha.Init();
sha.Update(buf, 64);
sha.Final(dest);
}
static void DeriveKey(NSha1::CContext &sha, Byte *key)
{
Byte digest[NSha1::kDigestSize];
sha.Final(digest);
Byte temp[NSha1::kDigestSize * 2];
DeriveKey2(digest, 0x36, temp);
DeriveKey2(digest, 0x5C, temp + NSha1::kDigestSize);
memcpy(key, temp, 32);
}
void CKeyInfo::SetPassword(const Byte *data, UInt32 size)
{
NSha1::CContext sha;
sha.Init();
sha.Update(data, size);
DeriveKey(sha, MasterKey);
}
STDMETHODIMP CBaseCoder::CryptoSetPassword(const Byte *data, UInt32 size)
{
_key.SetPassword(data, size);
return S_OK;
}
HRESULT CDecoder::ReadHeader(ISequentialInStream *inStream, UInt32 /* crc */, UInt64 /* unpackSize */)
{
Byte temp[4];
RINOK(ReadStream_FALSE(inStream, temp, 2));
_ivSize = GetUi16(temp);
if (_ivSize == 0)
{
return E_NOTIMPL;
/*
SetUi32(_iv, crc);
for (int i = 0; i < 8; i++)
_iv[4 + i] = (Byte)(unpackSize >> (8 * i));
SetUi32(_iv + 12, 0);
*/
}
else if (_ivSize == 16)
{
RINOK(ReadStream_FALSE(inStream, _iv, _ivSize));
}
else
return E_NOTIMPL;
RINOK(ReadStream_FALSE(inStream, temp, 4));
_remSize = GetUi32(temp);
const UInt32 kAlign = 16;
if (_remSize < 16 || _remSize > (1 << 18))
return E_NOTIMPL;
if (_remSize + kAlign > _buf.GetCapacity())
{
_buf.Free();
_buf.SetCapacity(_remSize + kAlign);
_bufAligned = (Byte *)((ptrdiff_t)((Byte *)_buf + kAlign - 1) & ~(ptrdiff_t)(kAlign - 1));
}
return ReadStream_FALSE(inStream, _bufAligned, _remSize);
}
HRESULT CDecoder::CheckPassword(bool &passwOK)
{
passwOK = false;
if (_remSize < 16)
return E_NOTIMPL;
Byte *p = _bufAligned;
UInt16 format = GetUi16(p);
if (format != 3)
return E_NOTIMPL;
UInt16 algId = GetUi16(p + 2);
if (algId < kAES128)
return E_NOTIMPL;
algId -= kAES128;
if (algId > 2)
return E_NOTIMPL;
UInt16 bitLen = GetUi16(p + 4);
UInt16 flags = GetUi16(p + 6);
if (algId * 64 + 128 != bitLen)
return E_NOTIMPL;
_key.KeySize = 16 + algId * 8;
if ((flags & 1) == 0)
return E_NOTIMPL;
if ((flags & 0x4000) != 0)
{
// Use 3DES
return E_NOTIMPL;
}
UInt32 rdSize = GetUi16(p + 8);
if ((rdSize & 0xF) != 0 || rdSize + 16 > _remSize)
return E_NOTIMPL;
memmove(p, p + 10, rdSize);
Byte *validData = p + rdSize + 16;
if (GetUi32(validData - 6) != 0) // reserved
return E_NOTIMPL;
UInt32 validSize = GetUi16(validData - 2);
if ((validSize & 0xF) != 0 || 16 + rdSize + validSize != _remSize)
return E_NOTIMPL;
{
RINOK(SetKey(_key.MasterKey, _key.KeySize));
RINOK(SetInitVector(_iv, 16));
Init();
Filter(p, rdSize);
}
Byte fileKey[32];
NSha1::CContext sha;
sha.Init();
sha.Update(_iv, 16);
sha.Update(p, rdSize - 16); // we don't use last 16 bytes (PAD bytes)
DeriveKey(sha, fileKey);
RINOK(SetKey(fileKey, _key.KeySize));
RINOK(SetInitVector(_iv, 16));
Init();
Filter(validData, validSize);
if (validSize < 4)
return E_NOTIMPL;
validSize -= 4;
if (GetUi32(validData + validSize) != CrcCalc(validData, validSize))
return S_OK;
passwOK = true;
Init();
return S_OK;
}
}}
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