Is it a bad idea to post a photo of your keyboard to social media?

Can I look at a photo of a keyboard and determine the password of an account?

Assuming a certain (set of) password(s) is the most commonly typed character sequence on a given keyboard:


Is the resolution in the photo of that keyboard sufficient to determine the most frequently used set of keys, by analyzing the grease patterns on them?
If I know the most frequently used keys, is a brute force attack now feasible, since I can limit the size of the dictionary?


This question is inspired by a time I saw a door protected by a numeric keypad, where the paint was missing on three of the keys. The room number was three digits, none of which had paint on their respective keys. Unsurprisingly, the combination was the room number reversed.

In some cases yes, you can guess the most frequently used keys by the wear marks. That's how I know that apparently I use the L, M, N, A and E keys a lot - the keys are now just black, the letter is faded.

And one special key being significantly more used than the others - unless it's "{", "}" or ";" and you happen to be a programmer - could allow to include that in a bruteforcing, or exclude others (this is definitely NOT my keyboard, but still):



But most people don't use the keyboard for just their passwords, and the wear pattern is also influenced by the stroke direction, angle and pressure - keys farther down the keyboard will be pressed differently from those nearer. The keys I wear faster appear to be exactly under the hand that controls them, and now that I noticed, I hit them harder than the rest (OK, also I'm a horrible typist).

The keyboard might hint (weakly, at that) at what the most frequent typed word, or anagrams thereof, might be. But that's not the same as your password except in very specific cases (e.g. an entry keypad).

In even more specific cases such as heat-conducting entry keypad, FIR or strong UV picture taken immediately after typing so that residual heat or fluorescence or phase interference from skin oils may be appreciated, you might be able to get something. But an ordinary picture conveys no such information.

So my opinion would be that keyboard pictures are mostly harmless.

On the other hand, I sometimes see Post-It with letters and numbers on them attached to monitors and on woodboards behind selfied people, so I'd also say that it's always a very good idea to review the photos (as well as whatever else) you post to the social media, looking at the goods with an attacker's eye:


inside view of (broken/defective/jimmied?) locks and/or brand names useful to research approaches
hints about location (this might be relevant to determine whether you're holidaying abroad, and estimate how long your home will be vacant)
valuable items (might give people ideas either about them, or about your wealth, which also could give people ideas)
discrepancies between what's shown and what you told anybody who might get to know, such as employer, insurance company, significant other(s), etc.


At least once, some months after this answer was posted, the last case actually happened.
