4. Compare Arbiter PUFs to Ring Oscillator PUFs. How does each one work?

5. We are manufacturing a new chip for an encryption application and want to make sure that the PUF properties are sufficient. We build 100 chips and our PUF responds to our challenge with 4 bits. Our enrollment temperature is is 25o C and regeneration is done all combinations of temperatures, e.g., 0oC, 25oC and 85oC, and supply voltages, -5%, nominal and +5%.. When we calculate and sum over all the HDintra values we get 587 What is the mean of HDintra using the method discussed in class? Assess the value you get. Is this a good number for reliability? Why or why not?

6. For the chips in problem 5 we want to look at the inter-chip differences to understand uniqueness. Assuming the same parameters as problem 6 and a sum of 14727 for HDinter overall then what the mean of HDinter using the method discussed in class? Would you consider this PUF? Why or why not? 7. Briefly describe the Butterfly PUF and what it is used for.