PHP : Crypt and Decryp

exemple :

//CRYPT and DECRYPT 
function bobbyCrypt( $string, $action = 'e' ,$secret_key ) 
{ $secret_iv = 'bibliogeek'; 
$output = false; $encrypt_method = "AES-256-CBC"; 
$key = hash( 'sha256', $secret_key );
 $iv = substr( hash( 'sha256', $secret_iv ), 0, 16 ); 
if( $action == 'e' ) 
{
 $output = base64_encode( openssl_encrypt( $string, $encrypt_method, $key, 0, $iv ) ); } else if( $action == 'd' ) 
{ 
$output = openssl_decrypt( base64_decode( $string ), $encrypt_method, $key, 0, $iv ); } return strval($output); }

$mdpCrypted=bobbyCrypt($_POST['password'],'e','maCléQueJePeuxChanger');
$mdpEncrypted=bobbyCrypt($mdpCrypted ,'d','maCléQueJePeuxChanger');
echo $mdpCrypted ."</br>";
echo $mdpEncrypte ;