We will be using the same method inside the driver helper class for all hash
types. This is the same function that has been used for the salted md5 hash
of phpBB 3.0.
PHPBB3-11610
The $2a$ prefix is the basic implementation with the $2y$ prefix extending
that class. However, the default hashes for phpBB should be generated with
$2y$ unless the PHP version is older than 5.3.7.
PHPBB3-11610