On Wed, Nov 16, 2016 at 3:19 PM, Thomas Morton <[email protected] > wrote:
> > > > Another idea might be to for the software to offer to create a random > > password for users at account creation time, and also to make the same > > offer at password change time. > > > > For example, even using automatically generated simple-looking and > > reasonably simple passwords like "little-center-ground-finger" > > consisting of 4 words between 5 and 8 characters long, will give an > > effective per-password entropy of 62 bits, significantly better than > > most user-generated passwords. > > If we did this it's worth pro-actively making the wordlist "hard". For > example, the words chosen above appear in the top-1000 most common English > words, and so therefore are trivially vulnerable to dictionary attacks > (hackers read XKCD too :)). > If you use the top-1000 most common English words (and the attacker knows you picked 4 random words from that list), 4 randomly-chosen words would have about 39.86 bits of entropy. That's a bit weak, but probably not entirely trivial (at 1000 guesses/second it'd take 31 years to try all the possibilities). Using a list of 1000 *un*common English words has the same level of entropy, since we assume the attacker can get the word list somehow (if nothing else, by using the service themselves a few thousand times and collecting all the words seen). If you want to increase the entropy, use a larger word list rather than a "harder" one. The XKCD comic seems to have used a 2048-word list for its 44-bit estimate. Using a list with 8836 words gets the same entropy (about 52.44 bits) as a completely-random 8-character password using any of the 94 characters I can easily type on my keyboard (e.g. "'>hZ|=S\*"). -- Brad Jorsch (Anomie) Senior Software Engineer Wikimedia Foundation _______________________________________________ Wikitech-l mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikitech-l
