4 ms·

Why wouldn't it know the direction of motion for the swipes and the orientation of the finger? Any mobile app has access to the touchscreen input which provides

Why wouldn't it know the direction of motion for the swipes and the orientation of the finger? Any mobile app has access to the touchscreen input which provides exactly that information.

kurthr 3y ago
Unless you're playing fruit ninja there's really quite little control over the speed and direction of swipes... many people swipe very little at all or with a different finger than they enroll in biometrics or type on the screen. Some even swipe with multiple fingers. Then there's the fact that there are more than 20 minutia per finger so when referring to orientation, this means the angles and what portion of the finger is in contact with the touch surface... and thus which of those minutia (swirl, end, fork, etc) are in generating any sound.
- PeterisP 3y ago
  What I hear in your comment is that if you want to steal people's fingerprints, you'd have to target-advertise them a clone of fruit ninja, possibly designed so that certain specific angles of fingers are clearly optimal for doing well at the game.
  - kurthr 3y ago
    If you want to steal a single print, you would need a moderately long game and pliable player along with wide angle synchronized video that imaged hand/finger orientation. If the video isn't good, or they use different fingers intermittently, or only one orientation, or they have a callus on their finger, or they have very fine/course ridges, too many forks/ends, an irregular accidental whorl or arch, or there's noise, etc... you wont' get a single print with high enough resolution to match. That still may not be a print they use for authentication. Most people use their forefinger or a thumb to swipe, and their thumbs to match/type, and multiple fingers or both thumbs to scroll/zoom. More interesting is that if one had full knowledge of a persons prints then perhaps with microphone, touch tracing, and wide angle video, one could compare expected vs measured sounds. This is a one-one confirmation rather than one-many match. Perhaps it could prevent long term usage after a person had unlocked their device and another was using it.

Why wouldn't it know the direction of motion for the swipes and the orientation of the finger? Any mobile app has access to the touchscreen input which provides exactly that information.

kurthr 3y ago

Unless you're playing fruit ninja there's really quite little control over the speed and direction of swipes... many people swipe very little at all or with a different finger than they enroll in biometrics or type on the screen. Some even swipe with multiple fingers. Then there's the fact that there are more than 20 minutia per finger so when referring to orientation, this means the angles and what portion of the finger is in contact with the touch surface... and thus which of those minutia (swirl, end, fork, etc) are in generating any sound.

PeterisP 3y ago
What I hear in your comment is that if you want to steal people's fingerprints, you'd have to target-advertise them a clone of fruit ninja, possibly designed so that certain specific angles of fingers are clearly optimal for doing well at the game.
- kurthr 3y ago
  If you want to steal a single print, you would need a moderately long game and pliable player along with wide angle synchronized video that imaged hand/finger orientation. If the video isn't good, or they use different fingers intermittently, or only one orientation, or they have a callus on their finger, or they have very fine/course ridges, too many forks/ends, an irregular accidental whorl or arch, or there's noise, etc... you wont' get a single print with high enough resolution to match. That still may not be a print they use for authentication. Most people use their forefinger or a thumb to swipe, and their thumbs to match/type, and multiple fingers or both thumbs to scroll/zoom. More interesting is that if one had full knowledge of a persons prints then perhaps with microphone, touch tracing, and wide angle video, one could compare expected vs measured sounds. This is a one-one confirmation rather than one-many match. Perhaps it could prevent long term usage after a person had unlocked their device and another was using it.