Randomization (Crypto Defense)
Randomization defenses introduce randomness into cryptographic execution (operation order, data location, masks) so that side-channel leakage decorrelates across executions.
Purpose
They prevent attackers from extracting stable key-related information from one or a few physical measurements.
Mechanism
Round-operation order, S-box table locations (against cache attacks), random delays (against timing alignment), and random intermediate masks are randomized. Averaged leakage over many executions trends to zero.
Use cases
- Defense against AES cache attacks
- RSA randomized exponentiation
- Smart-card random delays