Method Resync

src/cryptopp/gcm.cpp:437–480

}

void GCM_Base::Resync(const byte *iv, size_t len)
{
	BlockCipher &cipher = AccessBlockCipher();
	byte *hashBuffer = HashBuffer();

	if (len == 12)
	{
		memcpy(hashBuffer, iv, len);
		memset(hashBuffer+len, 0, 3);
		hashBuffer[len+3] = 1;
	}
	else
	{
		size_t origLen = len;
		memset(hashBuffer, 0, HASH_BLOCKSIZE);

		if (len >= HASH_BLOCKSIZE)
		{
			len = GCM_Base::AuthenticateBlocks(iv, len);
			iv += (origLen - len);
		}

		if (len > 0)
		{
			memcpy(m_buffer, iv, len);
			memset(m_buffer+len, 0, HASH_BLOCKSIZE-len);
			GCM_Base::AuthenticateBlocks(m_buffer, HASH_BLOCKSIZE);
		}

		PutBlock<word64, BigEndian, true>(NULL, m_buffer)(0)(origLen*8);
		GCM_Base::AuthenticateBlocks(m_buffer, HASH_BLOCKSIZE);

		ReverseHashBufferIfNeeded();
	}

	if (m_state >= State_IVSet)
		m_ctr.Resynchronize(hashBuffer, REQUIRED_BLOCKSIZE);
	else
		m_ctr.SetCipherWithIV(cipher, hashBuffer);

	m_ctr.Seek(HASH_BLOCKSIZE);

	memset(hashBuffer, 0, HASH_BLOCKSIZE);
}

unsigned int GCM_Base::OptimalDataAlignment() const
{