Method SetKeyWithoutResync

src/cryptopp/gcm.cpp:225–415

#endif

void GCM_Base::SetKeyWithoutResync(const byte *userKey, size_t keylength, const NameValuePairs &params)
{
	BlockCipher &blockCipher = AccessBlockCipher();
	blockCipher.SetKey(userKey, keylength, params);

	if (blockCipher.BlockSize() != REQUIRED_BLOCKSIZE)
		throw InvalidArgument(AlgorithmName() + ": block size of underlying block cipher is not 16");

	int tableSize, i, j, k;

#if CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE
	if (HasCLMUL())
	{
		// Avoid "parameter not used" error and suppress Coverity finding
		(void)params.GetIntValue(Name::TableSize(), tableSize);
		tableSize = s_clmulTableSizeInBlocks * REQUIRED_BLOCKSIZE;
	}
	else
#elif CRYPTOPP_BOOL_ARM_CRYPTO_INTRINSICS_AVAILABLE
	if (HasPMULL())
	{
		// Avoid "parameter not used" error and suppress Coverity finding
		(void)params.GetIntValue(Name::TableSize(), tableSize);
		tableSize = s_clmulTableSizeInBlocks * REQUIRED_BLOCKSIZE;
	}
	else
#endif
	{
		if (params.GetIntValue(Name::TableSize(), tableSize))
			tableSize = (tableSize >= 64*1024) ? 64*1024 : 2*1024;
		else
			tableSize = (GetTablesOption() == GCM_64K_Tables) ? 64*1024 : 2*1024;

#if defined(_MSC_VER) && (_MSC_VER < 1400)
		// VC 2003 workaround: compiler generates bad code for 64K tables
		tableSize = 2*1024;
#endif
	}

	m_buffer.resize(3*REQUIRED_BLOCKSIZE + tableSize);
	byte *table = MulTable();
	byte *hashKey = HashKey();
	memset(hashKey, 0, REQUIRED_BLOCKSIZE);
	blockCipher.ProcessBlock(hashKey);

#if CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE
	if (HasCLMUL())
	{
		const __m128i r = s_clmulConstants[0];
		__m128i h0 = _mm_shuffle_epi8(_mm_load_si128((__m128i *)(void *)hashKey), s_clmulConstants[1]);
		__m128i h = h0;

		for (i=0; i<tableSize; i+=32)
		{
			__m128i h1 = CLMUL_GF_Mul(h, h0, r);
			_mm_storel_epi64((__m128i *)(void *)(table+i), h);
			_mm_storeu_si128((__m128i *)(void *)(table+i+16), h1);
			_mm_storeu_si128((__m128i *)(void *)(table+i+8), h);