Imageboard poster IDs

I've noticed that /soc/ now has forced anon and IDs.
I assume they're generated from the poster's IP and the thread id, but what's the ENTERPRISE GOLD STANDARD for generating IDs on textboards? Something involving a crypt function, I imagine.
I also recall there being some threads here about someone cracking FV's user id to reveal that he's from Israel; if someone could point me to those threads and the code the cracker used, I'd be grateful.

sub make_id_code($$$)
{
    my ($ip,$time,$link)=@_;

    return EMAIL_ID if($link and DISPLAY_ID=~/link/i);
    return EMAIL_ID if($link=~/sage/i and DISPLAY_ID=~/sage/i);

    return resolve_host($ENV{REMOTE_ADDR}) if(DISPLAY_ID=~/host/i);
    return $ENV{REMOTE_ADDR} if(DISPLAY_ID=~/ip/i);

    my $string="";
    $string.=",".int($time/86400) if(DISPLAY_ID=~/day/i);
    $string.=",".$ENV{SCRIPT_NAME} if(DISPLAY_ID=~/board/i);

    return mask_ip($ENV{REMOTE_ADDR},make_key("mask",SECRET,32).$string) if(DISPLAY_ID=~/mask/i);

    return hide_data($ip.$string,6,"id",SECRET,1);
}