It will be helpful if following 2 additional filters in core.class.php in function shufflesalts() will be added:

$this->new_salts = apply_filters('salt_shaker_salts', $this->new_salts);
$this->salts_array = apply_filters('salt_shaker_salt_ids', $this->salts_array);

This will help me to add additional salt for instance if I am using JWT tokens which also require a secret key. Or, if permission granted I will commit the changes.