Hackers can forge keys with audio of door being unlocked

RESEARCHERS have discovered a way to forge keys using smartphone audio recordings of the sound of a door being unlocked.

Scientists from the National University of Singapore have published a paper which shows audio recordings of a key being inserted in a lock provide enough information for a computer to determine the shape of the key.

The system works by analysing audio recorded on a smartphone and filtering the sound to detect the clicks of the pins inside a lock against the key.

Then, it builds a virtual picture of the correct key based on the clicks of the lock to estimate the correct pattern of ridges found on the key.

The researchers said the system regularly managed to narrow down the correct key from a database of more than 330,000 potential keys to just three contenders.

Tom Van de Wiele, the principal security consultant at cybersecurity business F-Secure, said: “As someone who breaks into companies professionally, this of course is something that really appeals to me.”

The research is “really going to complement some of the other techniques that people are using for key copying”, Mr Van de Wiele said.

He advised any businesses which are concerned about the new key forging method to give security guards noisy keychains, which could help to mask the sound of a door being unlocked.

Security researchers have often used new technology to help them forge keys. In 2015, a team of researchers was able to use 3D printing to forge a set of keys used by the US Transportation Security Administration after a photograph of the master keys was found to have been accidentally published in a newspaper article.