PHP
/**
* @author Kevin van Zonneveld
* @author Simon Franz
* @author Deadfish
* @copyright 2008 Kevin van Zonneveld (http://kevin.vanzonneveld.net)
* @license http://www.opensource.org/licenses/bsd-license.PHP New BSD Licence
* @version SVN: Release: $Id: alphaID.inc.PHP 344 2009-06-10 17:43:59Z kevin $
* @link http://kevin.vanzonneveld.net/
*
* @param mixed $in String or long input to translate
* @param boolean $to_num Reverses translation when true
* @param mixed $pad_up Number or boolean padds the result up to a specified length
* @param string $passKey Supplying a password makes it harder to calculate the original ID
*
* @return mixed string or long
*/
function alphaID($in,$to_num = false,$pad_up = false,$passKey = null)
{
$index = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
if ($passKey !== null) {
// Although this function's purpose is to just make the
// ID short - and not so much secure,
// with this patch by Simon Franz (http://blog.snaky.org/)
// you can optionally supply a password to make it harder
// to calculate the corresponding numeric ID
for ($n = 0; $n<strlen($index); $n++) {
$i[] = substr( $index,$n,1);
}
$passhash = hash('sha256',$passKey);
$passhash = (strlen($passhash) < strlen($index))
? hash('sha512',$passKey)
: $passhash;
for ($n=0; $n < strlen($index); $n++) {
$p[] = substr($passhash,1);
}
array_multisort($p,SORT_DESC,$i);
$index = implode($i);
}
$base = strlen($index);
if ($to_num) {
// Digital number < 0) {
$out -= pow($base,$pad_up);
}
}
$out = sprintf('%F',$out);
$out = substr($out,strpos($out,'.'));
} else {
// Digital number -->> alphabet letter code
if (is_numeric($pad_up)) {
$pad_up--;
if ($pad_up > 0) {
$in += pow($base,$pad_up);
}
}
$out = "";
for ($t = floor(log($in,$base)); $t >= 0; $t--) {
$bcp = bcpow($base,$t);
$a = floor($in / $bcp) % $base;
$out = $out . substr($index,$a,1);
$in = $in - ($a * $bcp);
}
$out = strrev($out); // reverse
}
return $out;
}
