Re:Chorded keyboard
by api_or_ipa on Tuesday August 20, 2019 @02:47PM
(#20750524)
On my Galaxy S9+, I have 4 buttons: power, vol up/down and a stupid useless bixby button. Ignoring how to put it into 'password' mode, each of these buttons is effectively a bit. I assume you need at least 1 key to register an input (otherwise wait for a pause which I won't consider), so you get 15 possibilities. I think you could make a reasonably strong password using 4-8 chords (15^4-15^8 possibilities). Anyways, it's certainly better than those swipe passwords with an effective length of 9 Cr 4 == 128 which are readily seen and copied by nearby people.
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Do you mean to say there are 9 choose 4 == 126 possible combinations for a 3x3 pattern? I think this would only be true if you could use a maximum of four dots in the pattern, which isn't the case.
Although calculating it this way will double-count some patterns which include long lines, I would say that there ar far closer to 9! == 362880 passwords. Even if long lines cut that space in half, 150000 more than meets your minimum of 15^4.
Re:Chorded keyboard
by api_or_ipa on Wednesday August 21, 2019 @02:11PM
(#20759788)
You're right. I goofed on my analysis. Instead of chose, it's indeed a factorial. You're also right, you can chose up to 9 dots, so indeed it is up to 9! combinations. Thanks for catching that.