En el sitio de php, se dice que md5() es una funcion de hashing, no de encriptacion, por tanto es posible que 2 cadenas generen el mismo valor hash, luego otro usuario dice que no solo en teoria, sino que da un ejemplo de como pasa.
http://www.php.net/manual/es/function.md5.php
rikki dot tissier at gmail dot com
25-Oct-2004 12:06
It should be remembered that md5 is a *hashing algorithm* and *not* an encryption algorithm. md5 creates a hash representation of the data, it does not encrypt it.
It is therefore theoretically possible that 2 or more strings will generate the same hash when run through md5().
martin at marty dot me dot uk
27-Oct-2004 09:02
rikki dot tissier at gmail dot com,
Not only is it theoretically possible for two strings to have the same hash it does happen, for example try UPDATE table SET uId = md5(id) and then SELECT count(*) FROM table GROUP BY uId
Para funciones de encriptacion busca aqui la que mas te acomode:
http://dev.mysql.com/doc/mysql/en/En...functions.html