I get why you'd use a blacklist in general, but it seems obvious to me that in a case like this you do not want to allow any algo you haven't cleared first. Esp

I get why you'd use a blacklist in general, but it seems obvious to me that in a case like this you do not want to allow any algo you haven't cleared first. Especially since it may not be better! What if your underlying library decides it's gonna support md5 hashes for signatures?