System must copy pin code smartphones more difficult by using speaker

A South Korean researcher has devised a method to prevent the theft of PIN codes on smartphones. The user could unseen incorrect numbers in the code by covering the speaker, after which the phone ignores the incorrect numbers.

The system must work with sounds that are inaudible to humans, South Korean researcher Mun-Kyu Lee suggests in his paper. The microphone of the phone can pick up the signals that the speaker sends out. If the microphone does not pick up the signal, it means that the user has put their finger on the speaker.

The phone should then ignore input while pressing the screen lock when the user has their finger on the speaker. Those who are afraid that someone is looking at the code on their phone, could now and then put their finger on the speaker and insert a random number. If someone actually reads the code and tries to enter that code after theft, they have a non-working security code in their hands.

The system may have several drawbacks. Firstly, not every phone has the speaker on the back. Some phones have those on the bottom or the front and especially the latter causes problems with this system. In addition, a potential thief could also see when the user slides his finger on the back and read the real PIN code.