Mobile phones hold a trove of personal information that can be valuable to law enforcement investigating serious crimes, but they are notoriously hard to get into without a passcode or the owner’s fingerprint.
Police in the US found a way around this difficulty by 3D printing a murder victim’s finger to gain access to their smartphone and hopefully find evidence that would lead to the perpetrator of the crime.
The officers provided biometrics expert Anil Jain from Michigan State University with copies of the deceased’s fingerprints, taken before the murder, and asked him to create 3D printed replicas of all ten fingers.
“We don’t know which finger the suspect used,” Jain told Fusion. “We think it’s going to be the thumb or index finger – that’s what most people use – but we have all ten.”
Jain’s research focuses on making biometric identifiers, such as fingerprint scanners and facial recognition software, secure and difficult to trick. Helping law enforcement with their investigation is therefore doing the exact opposite. While hacking biometric security with measures such as a 3D printed replica finger could pose a security risk if the tools fell into the wrong hands, successfully doing so will inform Jain’s research.
“We do it for the fun,” said Jain.
A plastic replica of a finger isn’t enough to trick a fingerprint scanner, which requires a conductive surface, such as skin, to close tiny electrical circuits. To overcome this problem, Jain and his PhD student Sunpreet Arora covered the 3D printed fingertips with a thin layer of metallic particles.
Law enforcement and the researchers have not tried to unlock the victim’s phone using the 3D printed fingers yet, but will do so in the coming weeks.
Arora said he didn’t know how the police had come up with the idea of 3D printing the deaceased’s fingers to unlock the phone. “I think these guys go online to figure stuff out about how to hack phones,” he said to Fusion, “so we probably popped up.”
Gaining access to password and biometric-protected electronic devices is an ongoing struggle for law enforcement. Earlier this year, Apple entered into a months-long battle with the FBI after it refused to help the agency unlock the San Bernardino gunman’s iPhone 5c, which could have held evidence about the shooting that killed 14 people in December last year.
In the UK judge recently refused the National Crime Agency’s attempts to force alleged hacker Lauri Love to hand over the passwords and encryption keys to his seized computers and hard drives.