Hardware Security
Among power analysis attacks on chips performing cryptography, what characterizes differential power analysis (DPA)?
- AIt collects many power traces and processes them statistically to extract small key-dependent differences invisible in a single trace
- BA single power trace viewed by eye reveals the whole key
- CIt cuts the chip's power to extract the key
Show answer and explanation
Answer: A. It collects many power traces and processes them statistically to extract small key-dependent differences invisible in a single trace
CMOS circuits consume power when signals switch, so power varies slightly with the data processed. Simple power analysis reads the flow of processing from the shape of a single trace, whereas DPA collects traces from thousands of cryptographic operations and correlates them with intermediate values predicted for each key guess to find the right key. Its hallmark is extracting small differences buried in noise through statistics.
- A. Correct. Statistics bring small differences out of the noise.
- B. That would be simple power analysis (SPA) in the ideal case.
- C. Without power, nothing is processed.