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Comment by bluGill | Hacker News Reader

If someone has an infrared camera they get the same information: the heat of your fingers leaves traces on the keys you press.

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At least you can fake that out by pressing the wrong keys. Similar to how I enter my PIN into ATMs, I have my fingers covering all the keys at once with my hand open and my palm down. All the keys get touched, albeit with different amounts of pressure, but picking up that sort of difference would be error prone.

I work with infrared cameras, I'll check this out tomorrow! Useful for things like seeing if someone's just left the office for lunch because their chair's warm.

Reminds me of the scene in one of Dan Brown's books where they catch the protagonist by noticing a conveyor belt has warmed up (which he lay on to escape). The first time I read that I thought it was nonsense, but having used decent cameras I'm inclined to believe it now.

like... i get that this is technically true, but you see how the addition of an infrared camera to the mix makes things much more cumbersome? or rather, do you see how obviating the need for an infrared camera makes discovering the password much easier (because you don't have to acquire and place an infrared camera, you're just handed the info via the visible spectrum)?

clever trick with the infra cam, but i don't think you've showed the equivalence of the situations in any practical sense. maybe that wasn't your point, and you were just offering a sorta-similar-but-not-really detection technique?

The infrared camera is not something exotic. Anyone who is interested in discovering passwords will have one. Most people do not care - if I would post my bank account password here most people wouldn't attempt to login to see if it was real, and of those that do most wouldn't do anything bad. I still don't post my bank info because of the tiny number of people who would abuse it: they are mostly the same people as who would buy the infrared camera.

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