BTW, apropos checksums: when you use "AND $FFFF" for the checksum, like in my example, you have to realize that the checksum will never be higher than 65535. This means, a hacker could brute force the right checksum with a max of 65535 attempts. If your server has no automatic recognition of brute force attacks or dos attacks, this will take only a while for the hacker.
Using a 32 Bit checksum (and $FFFFFFFF) will make it much harder for the cheater, since it allows 4 billion possible checksums. But in that case you should also use a higher multiplier than 1234 for the digits, eg. 12345678.
That said, since the checksum code is not pubic, the hacker won't know if it's 16 bit or 32 bit. You may also use an uncommon checksum, like a 25 bit checksum:
checksum = checksum AND %1111111111111111111111111
Using a 32 Bit checksum (and $FFFFFFFF) will make it much harder for the cheater, since it allows 4 billion possible checksums. But in that case you should also use a higher multiplier than 1234 for the digits, eg. 12345678.
That said, since the checksum code is not pubic, the hacker won't know if it's 16 bit or 32 bit. You may also use an uncommon checksum, like a 25 bit checksum:
checksum = checksum AND %1111111111111111111111111