Posted by Toby Inkster on 01/04/07 10:17

Tom wrote:

> 10 => DFG56JKG4 => 10
>
> How do I accomplish that?

How about this...

define('MYSECRET','Some unguessable string');

function int2code ($i)
{
$md5 = strtoupper(md5(MYSECRET.$i));
$mdStart = substr($md5, 0, 4);
$mdEnd = substr($md5, 28, 4);
return $mdStart.$i.$mdEnd;
}

function code2int ($code)
{
preg_match('/^([A-F0-9]{4})([0-9]+)([A-F0-9]{4})$/', $code, $matches);
$i = $matches[2];

$md5 = strtoupper(md5(MYSECRET.$i));
$mdStart = substr($md5, 0, 4);
$mdEnd = substr($md5, 28, 4);
if ($mdStart.$i.$mdEnd==$code)
return $i;

return FALSE; // Invalid code!
}

--
Toby A Inkster BSc (Hons) ARCS
Contact Me ~ http://tobyinkster.co.uk/contact

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