3 ms·

That's only if your password is weak. If no one's ever seen it before (generated by password manager) it wouldn't really help much.

• zaroth 9y ago
  The resolution of the discriminator has nothing to do with the strength of your password. Having the first 20 bits of the hash certainly isn’t the same as having the whole thing, but the simple math says that only 1 in a million wrong guesses will match. This is very powerful, for example, if you have a strong hash which you want to crack along with the first 5 characters of the SHA1 because then you only have to run the slow hash 1 in a million times. It’s also very powerful if you want to do an online attack because you can narrow down your guesses quite significantly. Lastly, if you are logging in with keys (random entropy encoded as human readable string) rather than passwords of course none of this concerns you in the slightest, nor do you have any use for this API in the slightest. To state it another way, if you have 80 bits of entropy in your password, maybe no big deal to throw away 20 bits worth (but for what purpose?). However the average password has less than 30 bits of entropy, so throwing away 20 bits is a big deal. The end result is there’s a lot of trust being placed in this API, and in particular the idea that services should be calling out to it as part of a login process, or that we should be training average users to test their passwords in a webform, that is concerning.