L2J Server

Posted: **Sat Apr 30, 2011 8:35 pm**

Hello there.
I'm trying to ressurect a dead MMO (dead not because of community i might say) - im doing it for fun and to strengthen my proramming knowledge. It is the first project i try to reverse engineer so yeah it's pretty difficult for me :/

So is there any C# programmer with decent knowledge in blowfish encryption/decryption willing to help me ? Having in mind that i have the encryption key, the P and S boxes exported from the client !

I've tried finding open blowfish libraries and edit them to my taste but i'm doing it wrong :/
So if there is somebody willing to help me please leave a comment and i'll contact you with more informaton.

P.S: Yeah i know this is Java based community but you are like the best open source community that i know of so i'm giving it a shot

dont kill me

Posted: **Thu May 19, 2011 3:45 am**

http://www.koders.com/csharp/fidD5E0D7A ... 1B953.aspx

This is the first result in google for "c# blowfish"...

Don`t forget to append the padding bytes:

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 packetSize += 4;packetSize += (8 - packetSize % 8);

and after the ofc the padding:

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 final int count = offset + size - 4; //offset = starting byte of packet, size = packetSize (with padding bytes)int checksum = 0;for (; offset < count; offset += 4){    checksum ^= ArrayUtil.getD(raw, offset); // little endian 4bytes starting at offset = int}ArrayUtil.putD(raw, offset, checksum); // little endian 4bytesstarting at offset = int

Here is the code to check if padding is ok:

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 if (size <= 4 || (size & 0x03) != 0) // min packet size is 4 and the packet len must always be a base of 4, so 4 - 8 - 12 - 16 etc    return false; final int count = offset + size - 4;int checksum = 0;    for (; offset < count; offset += 4){    checksum ^= ArrayUtil.getD(raw, offset);} return checksum == ArrayUtil.getD(raw, offset); // returns true if the checksum matches expected: OK

So when sending a packet append the padding bytes then append the checksum then use the blowfish.
When receiving use blowfish and then check checksum.

Posted: **Fri May 20, 2011 8:06 am**

The blowfish algorithm is slightly changed. I know it's stupid but hey ... it is not me who made the client in the first place

Thanks for the links btw and especially for the checksum code /socialbow (l2 style)

PS: We've figured it out already

L2J Server

Encyption experts ?

Encyption experts ?

Re: Encyption experts ?

Re: Encyption experts ?