Arbiter pufs

<p><img alt="Pasted image 20260324152821.png" class="wikiimage" src="/pasted image 20260324152821.png" /></p> <p>The idea of an <strong>APUF</strong> (arbiter <a class="wikilink" href="/physical_unclonable_function/">Physical Unclonable Function</a>) is to use small differences in manufacturing to create unique systems. Specifically, the picture above shows a series of MUX connected symmetrically. Given a challenge ($\vec{c}$) the signal will propagate differently due to different (and minute) delays in each gate. </p> <p>The arbiter is essentially a latch that gives a $1$ or a $0$ based on which signal arrived before. </p> <p>For each challenge $\vec{c}$, the output $r$ will depend on the underlaying system. It is possible to an extension to $2D$ so that the PUF behaves like a matrix: $A\times\vec{c}=\vec{r}$ increasing the total CRP space and making it more robust. </p> <p>However, this specific implementation of an APUF is prone to modelling attacks, i.e. predicting the behaviour by looking at the differences in manufacturing itself.</p>