Silex 2.0：不支持算法“bcrypt”

I have a Silex project where i'm upgrading from Silex 1.3 to Silex 2.0. The project works fine on 1.3 but i'm stuck with a bcryt encryption error since it seems default encoding changed with Silex 2.0.

Silex throw error The algorithm "bcrypt" is not supported with those 2 lines :

$pass_encoder = new MessageDigestPasswordEncoder('bcrypt', true, 13);
$pass = $pass_encoder->encodePassword($si_pass, $si_salt);

I'm using XAMPP with PHP 5.5.28, mcrypt support is enabled and mcrypt_filter support is enabled.

Thanks for any help !

Try to use bcrypt encoder

$pass_encoder = new \Symfony\Component\Security\Core\Encoder\BCryptPasswordEncoder(13);