The researchers' physically unclonable function (PUF) technology uses a microchip's physical imperfections to produce unique security keys that can be used to authenticate devices linked to the IoT. The improved reliability of their technology, say the researchers, is provided through the generation of two unique fingerprints for each PUF.
This "zero-overhead" method uses the same PUF components to make both keys and does not require extra area and latency because of a design feature that also allows their PUF to be about 15 times more energy efficient than previously published versions.
"Basically each PUF unit can work in two modes," says Kaiyuan Yang, assistant professor of electrical and computer engineering. "In the first mode, it creates one fingerprint, and in the other mode it gives a second fingerprint."
"Each one is a unique identifier, and dual keys are much better for reliability," says Yang. "On the off chance the device fails in the first mode, it can use the second key. The probability that it will fail in both modes is extremely small."
PUF fingerprints have several of the same advantages as human fingerprints as a means of authentication, says Yang.
"First, they are unique. You don't have to worry about two people having the same fingerprint," says Yang. "Second, they are bonded to the individual. You cannot change your fingerprint or copy it to someone else's finger. And finally, a fingerprint is unclonable. There's no way to create a new person who has the same fingerprint as someone else."
PUF-derived encryption keys are also unique, bonded, and unclonable, say the researchers. While the differences among more than a billion transistors crammed onto a chip half the size of a credit card may amount to a few more atoms in one or a few less in another, those miniscule differences are enough to produce the electronic fingerprints used to make PUF keys.
For a 128-bit key, a PUF device would