Memory-based pufs

A Physical Unclonable Function relies on a manufacturing process with a level of stochasticity that makes it impossible to reproduce. In semiconductor industry, this happens with RAM memory: at the moment of power up, each bit will get randomly assigned values of $1$ or $0$. This is unique to the chip, and can't be controlled (similarly to what happens with Arbiter PUFs using the MUX design).

There are some subtleties in the architecture in order to define what is a "Challenge", given that the bits are already set since power on.

As far as I understand, these types of PUFs show a high degree of correlation (when there's a $1$ there's a higher chance of having another $1$ close by) limiting the total space. They can also be inspected from the outside in a non-destructive test, allowing some form of impersonation (given the bit is set at power up, it is already available).

On the other hand, as far as I understand, they are easy to manufacture, quite stable over time, and with good error correcting algorithms in case there is drift over time.