[bitfolk] Password hashes, was Re: Please log in...

Note: these are some musings on password hashes, which do not invalidate Andy's call to action! On Fri, Dec 28, 2018 at 09:22:15PM +0000, Andy Smith wrote: This actually isn't true! You can upgrade any half-decent hash scheme by simply applying the new hash to the old hash of the password. So for example, you have in the past used MD5 without a salt as hashing algorithm and you want to upgrade it to bcrypt which is slower (a good thing) and comes with a salt. Then you just take MD5(password) and replace it with bcrypt(MD5(password)) -- this doesn't require you to know the password -- and update your password-checking functionality accordingly. People tend to be reluctant to do this, because MD5 is broken as a hashing algorithm (collisions can be created) but that isn't relevant here. Mind you, if you were to apply this on a live website, I would not blindly trust a guy on some mailing list, but here is a reference on how Facebook did this, for those interested: http://bristolcrypto.blogspot.com/2015/01/password-hashing-according-to-fac… Martijn