[AndMetal]

Did a little more digging, and came up with this:

common/EQStream.cpp:

 1003 void EQStream::Process(const unsigned char *buffer, const uint32 length)
 1004 {
 1005 static unsigned char newbuffer[2048];
 1006 uint32 newlength=0;
 1007 	if (EQProtocolPacket::ValidateCRC(buffer,length,Key)) {
 1008 		if (compressed) {
 1009 			newlength=EQProtocolPacket::Decompress(buffer,length,newbuffer,2048);
 1010 		} else {
 1011 			memcpy(newbuffer,buffer,length);
 1012 			newlength=length;
 1013 			if (encoded)
 1014 				EQProtocolPacket::ChatDecode(newbuffer,newlength-2,Key);
 1015 		}
 1016 		if (buffer[1]!=0x01 && buffer[1]!=0x02 && buffer[1]!=0x1d)
 1017 			newlength-=2;
 1018 		EQProtocolPacket *p = MakeProtocolPacket(newbuffer,newlength);
 1019 		ProcessPacket(p);
 1020 		delete p;
 1021 		ProcessQueue();
 1022 	} else {
 1023 		_log(NET__DEBUG, _L "Incoming packet failed checksum" __L);
 1024 		_hex(NET__NET_CREATE_HEX, buffer, length);
 1025 	}
 1026 }

Key is defined a few times throughout EQStream.cpp, and it seems to be somewhat dependent on the type of packet. For the most part, I think it's defined as 0:

   53 	Key=0;

Here is an example of where it isn't:

  299 #ifndef COLLECTOR
  300 			Key=0x11223344;
  301 			SendSessionResponse();
  302 #endif

  310 			Key=ntohl(Response->Key);

  802 	Response->Key=htonl(Key);

I'd dig deeper, but it's late for me. Good luck with figuring out the encoding