tibia packet decryption

[selo]

hello
could some one explain for me please how can the forgotten server decrypt tibia packets
is the developers or the forgotten server know the Decryption code (RSA KEY) or what is the matter
if some one know please explain for me how can this happen
rep++ for the member that can help me

 

[Cykotitan]

From protocollogin.cpp: (also found in protocolgame.cpp, protocolold.cpp)

bool ProtocolLogin::parseFirstPacket(NetworkMessage& msg)
{
	if(
#if defined(WINDOWS) && !defined(__CONSOLE__)
		!GUI::getInstance()->m_connections ||
#endif
		g_game.getGameState() == GAME_STATE_SHUTDOWN)
	{
		getConnection()->close();
		return false;
	}

	uint32_t clientIp = getConnection()->getIP();
	/*uint16_t operatingSystem = msg.GetU16();*/msg.SkipBytes(2);
	uint16_t version = msg.GetU16();

	msg.SkipBytes(12);
[B]	if(![COLOR="red"]RSA_decrypt[/COLOR](msg))[/B]
	{
		getConnection()->close();
		return false;
	}

From protocol.cpp:

bool Protocol::RSA_decrypt(RSA* rsa, NetworkMessage& msg)
{
	if(msg.getMessageLength() - msg.getReadPos() != 128)
	{
		std::cout << "[Warning - Protocol::RSA_decrypt] Not valid packet size" << std::endl;
		return false;
	}

	[B][COLOR="red"]rsa[/COLOR]->[COLOR="red"]decrypt[/COLOR]((char*)(msg.getBuffer() + msg.getReadPos()), 128);[/B]
	if(!msg.GetByte())
		return true;

	std::cout << "[Warning - Protocol::RSA_decrypt] First byte != 0" << std::endl;
	return false;
}

From rsa.cpp:
[cpp]void RSA::decrypt(char* msg, int32_t size)
{
boost::recursive_mutex::scoped_lock lockClass(rsaLock);

mpz_t c,v1,v2,u2,tmp;
mpz_init2(c, 1024);
mpz_init2(v1, 1024);
mpz_init2(v2, 1024);
mpz_init2(u2, 1024);
mpz_init2(tmp, 1024);

mpz_import(c, 128, 1, 1, 0, 0, msg);

mpz_mod(tmp, c, m_p);
mpz_powm(v1, tmp, m_dp, m_p);
mpz_mod(tmp, c, m_q);
mpz_powm(v2, tmp, m_dq, m_q);
mpz_sub(u2, v2, v1);
mpz_mul(tmp, u2, m_u);
mpz_mod(u2, tmp, m_q);
if(mpz_cmp_si(u2, 0) < 0)
{
mpz_add(tmp, u2, m_q);
mpz_set(u2, tmp);
}
mpz_mul(tmp, u2, m_p);
mpz_set_ui(c, 0);
mpz_add(c, v1, tmp);

size_t count = (mpz_sizeinbase(c, 2) + 7)/8;
memset(msg, 0, 128 - count);
mpz_export(&msg[128 - count], NULL, 1, 1, 0, 0, c);

mpz_clear(c);
mpz_clear(v1);
mpz_clear(v2);
mpz_clear(u2);
mpz_clear(tmp);
}[/cpp]

 

[selo]

is thats all??
im just a big noob

 

[selo]

i dont understand how can this work
can u explain more please
anyway rep++ for u

 

[Cykotitan]

I don't know either, look at it
By the looks of it, someone who's good at math has made it originally

 

[stian]

Look at 0.4 code. It's much simpler since we use OpenSSL instead of rsa.cpp. RSA are explained @wikipedia.

EDIT: Don't forget we got XTEA too.

 

[Cykotitan]

He isn't a premium user

 

[selo]

hehe,thnx for ur help men

 

[selo]

hmm,im wondering how can the forgotten server decrypt that with out RSA key ?

 

[Cykotitan]

hmm,im wondering how can the forgotten server decrypt that with out RSA key ?

The private key is in otserv.cpp

 

[selo]

ahhh,thnx man u rly so kind