Encriptar identificação

Use um hash reversível ou base64

https://raw.githubusercontent.com/sagargp/coolsitebro/master/alphaID.php

<?php
/**
* Translates a number to a short alhanumeric version
*
* Translated any number up to 9007199254740992
* to a shorter version in letters e.g.:
* 9007199254740989 --> PpQXn7COf
*
* specifiying the second argument true, it will
* translate back e.g.:
* PpQXn7COf --> 9007199254740989
*
* this function is based on any2dec && dec2any by
* fragmer[at]mail[dot]ru
* see: http://nl3.php.net/manual/en/function.base-convert.php#52450
*
* If you want the alphaID to be at least 3 letter long, use the
* $pad_up = 3 argument
*
* In most cases this is better than totally random ID generators
* because this can easily avoid duplicate ID's.
* For example if you correlate the alpha ID to an auto incrementing ID
* in your database, you're done.
*
* The reverse is done because it makes it slightly more cryptic,
* but it also makes it easier to spread lots of IDs in different
* directories on your filesystem. Example:

 * $part1 = substr($alpha_id,0,1);
 * $part2 = substr($alpha_id,1,1);
 * $part3 = substr($alpha_id,2,strlen($alpha_id));
 * $destindir = "/".$part1."/".$part2."/".$part3;
 * // by reversing, directories are more evenly spread out. The
 * // first 26 directories already occupy 26 main levels
 *
 * more info on limitation:
 * - [http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/165372](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/165372)
 *
 * if you really need this for bigger numbers you probably have to look
 * at things like: [http://theserverpages.com/php/manual/en/ref.bc.php](http://theserverpages.com/php/manual/en/ref.bc.php)
 * or: [http://theserverpages.com/php/manual/en/ref.gmp.php](http://theserverpages.com/php/manual/en/ref.gmp.php)
 * but I haven't really dugg into this. If you have more info on those
 * matters feel free to leave a comment.
 *
 * The following code block can be utilized by PEAR's Testing_DocTest
 * <code>
 * // Input //
 * $number_in = 2188847690240;
 * $alpha_in = "SpQXn7Cb";
 *
 * // Execute //
 * $alpha_out = alphaID($number_in, false, 8);
 * $number_out = alphaID($alpha_in, true, 8);
 *
 * if ($number_in != $number_out) {
 * echo "Conversion failure, ".$alpha_in." returns ".$number_out." instead of the ";
 * echo "desired: ".$number_in."\n";
 * }
 * if ($alpha_in != $alpha_out) {
 * echo "Conversion failure, ".$number_in." returns ".$alpha_out." instead of the ";
 * echo "desired: ".$alpha_in."\n";
 * }
 *
 * // Show //
 * echo $number_out." => ".$alpha_out."\n";
 * echo $alpha_in." => ".$number_out."\n";
 * echo alphaID(238328, false)." => ".alphaID(alphaID(238328, false), true)."\n";
 *
 * // expects:
 * // 2188847690240 => SpQXn7Cb
 * // SpQXn7Cb => 2188847690240
 * // aaab => 238328
 *
 * </code>
 *
 * @author Kevin van Zonneveld <kevin@vanzonneveld.net>
 * @author Simon Franz
 * @author Deadfish
 * @copyright 2008 Kevin van Zonneveld ([http://kevin.vanzonneveld.net](http://kevin.vanzonneveld.net))
 * @license [http://www.opensource.org/licenses/bsd-license.php](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](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/](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, $n ,1);
 }

 array_multisort($p, SORT_DESC, $i);
 $index = implode($i);
 }

 $base = strlen($index);

 if ($to_num) {
 // Digital number <<-- alphabet letter code
 $in = strrev($in);
 $out = 0;
 $len = strlen($in) - 1;
 for ($t = 0; $t <= $len; $t++) {
 $bcpow = bcpow($base, $len - $t);
 $out = $out + strpos($index, substr($in, $t, 1)) * $bcpow;
 }

 if (is_numeric($pad_up)) {
 $pad_up--;
 if ($pad_up > 0) {
 $out -= pow($base, $pad_up);
 }
 }
 $out = sprintf('%F', $out);
 $out = substr($out, 0, 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;
}
?>

nota: é necessário possuir a lib bcmath para usar a função alphaID.

Em ambiente unix, a instalação padrão do php não possui o bcmath. Para resolver, instale-o.

yum install php-bcmath

base64_encode é o mais fácil. Eu uso bastante. Claro que, por ser reversível, o cara que manjar um pouco descobre o ID, mas pra um cliente ou outro funciona bem.

obrigado galera. Vlw mesmo