When the client sends a packet to the server, the first byte encapsulates its opcode. This specific opcode is encrypted with a value generated by the ISAAC PRNG initialized with dynamically generated seeds during the login block. The server decrypts it and associates the opcode to the packet's respective predefined size. If the packet does not contain a fixed size, the opcode will be followed by either a byte or a word - varying per packet - for its proper size. This is then followed by the payload.
