The authors of 2010/251 are wildly exaggerating the impact of their results when they claim that they can clone many types of PUFs and thus break "essentially all" PUF applications and protocols.

The easiest way to understand this is to consider the classic _linear_ PUFs (the original optical PUFs using speckle patterns). For these PUFs, the type of "break" carried out in 2010/251 is trivial by design: anyone with access to the PUF can easily see the PUF behavior and build a _large_ device (camera + laptop + projector) that simulates the PUF. The PUF is nevertheless unbroken: the attacker is unable to manufacture a _small_ device that simulates the PUF. The PUF user verifies the PUF size, of course.

---D. J. Bernstein
Research Professor, Computer Science, University of Illinois at Chicago

luzagodom Wrote:
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> 2010/251 PUF exaggeration. Posted by: djb (IP
> Logged). Date: 05 May 2010 08:10. The authors of
> 2010/251 are wildly exaggerating the impact of
> their results


I must say that I desagree, but that is my opinion.