加密密码Mcrypt php比较表单和数据库值

I'm creating users with encrypted passwords on database using mcrypt method like this:

                    $key = '1234567890123456';
                    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
                    $iv = mcrypt_create_iv($iv_size);
                    $encryp_pass = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $password2, MCRYPT_MODE_ECB, $iv);
                    mysql_query("UPDATE usuarios SET pass_usuario = '".$encryp_pass."' WHERE id_usuario = '".$id_user[0]."' ");

...so that user just created is stored in database with his password encrypted.

Now, when that user logs into the system what i do (or what i'm trying to do) is encrypt the password he inputs on the textfield so then i compare that value with the value on the database. I encrypt the password the same way i did when creating the user like this:

$key = '1234567890123456';
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
$iv = mcrypt_create_iv($iv_size);
$encryp_pass = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $password, MCRYPT_MODE_ECB, $iv);

$query_pass_existe = mysql_query("SELECT pass_usuario FROM usuarios WHERE nick_usuario = '".$nick."'");
$pass_user_fromDB = mysql_fetch_assoc($query_pass_existe);

Then i compare both passwords: the one extracted from database and the one encrypted from the login form:

if (utf8_encode($encryp_pass) == utf8_encode($pass_user_fromDB['pass_usuario'])) {

    echo 'both are equals';

 }else{
       echo 'they're totally different';
 }

Right now, i'm getting both as different. So i print them to see the result:

echo utf8_decode($pass_user_fromDB['pass_usuario']);
echo "<br>";
echo utf8_decode($encryp_pass);
echo "<br>";

but they are ALMOST alike, take a look:

=???0?1y?Y7h???[.?0????1m
=???0?1y?Y7h???\[.?0????1m

They are ALMOST the same but because of that \ i can't continue with the login successfully. I've checked the column and i have set it as: utf8_general_ci. I'm thinking on using AES encryption but i read on this article that for mysql is better to use mcrypt.