C++ (Cpp) ustring::getUstring示例

ustring PubAddr::decode(ustring data, ustring privK)
{
	unsigned int p = 0;

	ustring IV = data.getUstring(16, p);
	unsigned int curveType = data.getInt16(p);
	unsigned int Xlen = data.getInt16(p);
	ustring X = data.getUstring(Xlen, p);
	unsigned int Ylen = data.getInt16(p);
	ustring Y = data.getUstring(Ylen, p);
	ustring cipherText = data.getUstring(data.size() - (p + 32), p);
	ustring MAC = data.getUstring(32, p);

	ustring pubK;
	pubK += 0x04;
	pubK += X;
	pubK += Y;


	OID CURVE = secp256k1();
	AutoSeededRandomPool rng;

	ECDH < ECP >::Domain dhA(CURVE), dhB(CURVE);
	SecByteBlock privA(privK.c_str(), dhA.PrivateKeyLength());
	SecByteBlock pubB(pubK.c_str(), dhB.PublicKeyLength());

	if (dhA.AgreedValueLength() != dhB.AgreedValueLength())
	{
		throw runtime_error("Shared shared size mismatch");
	}
	SecByteBlock sharedA(dhA.AgreedValueLength()), sharedB(dhB.AgreedValueLength());

	if (!dhA.Agree(sharedA, privA, pubB))
		throw runtime_error("Failed to reach shared secret (A)");


	Integer ssa, ssb;

	ssa.Decode(sharedA.BytePtr(), sharedA.SizeInBytes());

	uint8_t H[CryptoPP::SHA512::DIGESTSIZE];
	CryptoPP::SHA512 hash;

	hash.CalculateDigest(H, sharedA.BytePtr(), sharedA.SizeInBytes());



	AutoSeededRandomPool prng;

	byte key[32];

	memcpy(key, H, sizeof(key));

	byte Hkey[32];

	memcpy(Hkey, &(H[32]), sizeof(Hkey));

	byte iv[16];

	memcpy(iv, IV.c_str(), IV.size());

	string cipher = cipherText.toString(), encoded, recovered;

	string HMacPlain;

	p = 0;
	HMacPlain += data.getString(data.size()-32,p);

	string mac;

	try
	{
		HMAC<SHA256> hmac(Hkey, 32);
		StringSource s(HMacPlain, true,
			new HashFilter(hmac,
				new StringSink(mac)
				)
			);
	}
	catch (const CryptoPP::Exception& e)
	{
		throw runtime_error(e.what());
	}

	if (mac != MAC.toString())
		throw runtime_error("mac doesnt match");

	try
	{
		CBC_Mode< AES >::Decryption d;
		d.SetKeyWithIV(key, sizeof(key), iv);

		// The StreamTransformationFilter removes
		//  padding as required.
		StringSource s(cipher, true,
			new StreamTransformationFilter(d,
				new StringSink(recovered)
				) // StreamTransformationFilter
			); // StringSource
	}
	catch (const CryptoPP::Exception& e)
	{
		throw runtime_error(e.what());
	}

	ustring result;
	result.fromString(recovered);
	return result;
}