Hardware Security
What property does an SRAM PUF exploit?
- ARight after power-on, each SRAM cell tends to settle to 0 or 1 depending on transistor variation
- BSRAM retains data permanently with power off
- CEvery SRAM cell always becomes 0 at power-on
Show answer and explanation
Answer: A. Right after power-on, each SRAM cell tends to settle to 0 or 1 depending on transistor variation
An SRAM cell is a pair of cross-coupled inverters, and which way it falls right after power-on is decided by slight strength differences between the transistors of the two inverters. So the pattern of initial values across cells is unique to each chip and reappears almost identically at every power-on. The advantage is that it uses SRAM most chips already have, with no special circuitry.
- A. Correct. The pattern of initial values is the chip's fingerprint.
- B. SRAM is volatile.
- C. If all were 0, there would be no fingerprint.