Phone makers could easily increase security by making it harder to match the partial fingerprint, he said, “but the average phone company is more worried about you being annoyed
that you have to put your finger against the phone two or three times than they are with someone breaking into it.”
Adding a larger fingerprint sensor would also decrease the risk, Dr. Boehnen said.
When a user sets up fingerprint security on an Apple iPhone or a phone
that runs Google’s Android software, the phone typically takes eight to 10 images of a finger to make it easier to make a match.
Phone makers have acknowledged that fingerprint sensors are not foolproof, but said
that the ease of touching a finger to unlock a phone meant that more users actually turned on security features instead of leaving their phones unlocked — a common habit in the early days of smartphones.
“If all I want to do is take your phone and use your Apple Pay to buy stuff, if I can get into 1 in 10 phones, that’s not bad odds.”
Full human fingerprints are difficult to falsify, but the finger scanners on phones are so small that they read only partial fingerprints.
