Method CheckKey

src/cryptopp/default.cpp:182–212

template <class BC, class H, class Info>
void DataDecryptor<BC,H,Info>::CheckKey(const byte *salt, const byte *keyCheck)
{
	SecByteBlock check(STDMAX((unsigned int)2*BLOCKSIZE, (unsigned int)DIGESTSIZE));

	H hash;
	hash.Update(m_passphrase, m_passphrase.size());
	hash.Update(salt, SALTLENGTH);
	hash.Final(check);

	SecByteBlock key(KEYLENGTH);
	SecByteBlock IV(BLOCKSIZE);
	GenerateKeyIV<BC,H,Info>(m_passphrase, m_passphrase.size(), salt, SALTLENGTH, ITERATIONS, key, IV);

	m_cipher.SetKeyWithIV(key, key.size(), IV);
	member_ptr<StreamTransformationFilter> decryptor(new StreamTransformationFilter(m_cipher));

	decryptor->Put(keyCheck, BLOCKSIZE);
	decryptor->ForceNextPut();
	decryptor->Get(check+BLOCKSIZE, BLOCKSIZE);

	SetFilter(decryptor.release());

	if (!VerifyBufsEqual(check, check+BLOCKSIZE, BLOCKSIZE))
	{
		m_state = KEY_BAD;
		if (m_throwException)
			throw KeyBadErr();
	}
	else
		m_state = KEY_GOOD;
}

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