Applied DNA Sciences Inc (APDN)

[RodeKroet]

Because PUF fingerprints are determined during the manufacturing process, they are extremely difficult to replicate. But they suffer from several problems that have prevented their widespread adoption. The first is instability. The tiny variations in transistors that underlie the chip’s digital signature can fluctuate along with the supply voltage or the ambient temperature. And as a transistor ages, its switching speed can slow down.

These problems can be addressed to some extent by increasing the number of signatures used for each chip. In this way, a chip can be recognized based on a less-than-perfect match over a large number of signatures; when it comes to detecting clones, a 90 percent match for 100 signatures may be as good as or better than a perfect match for just one signature. But nobody has yet figured out a way to avoid unstable signatures altogether.