What defensive technique reduces timing or power leakage?

• A. Constant-time operations
• B. Data masking
• C. Key rotation
• D. Public-key cryptography

Answer: (A)

The main idea is preventing side-channel information from leaking through how long an operation takes. Making every operation run in the same amount of time regardless of secret data stops an attacker from inferencing secrets just by measuring timing. That’s what constant-time operations do: code paths, memory access, and loop lengths do not vary with the input or secret values, so timing won’t reveal bits of the key or other sensitive data. This defense is the most direct way to reduce timing leakage, and it can also help limit power leakage when you avoid data-dependent variations that would also swing power use.

Data masking focuses on weakening power leakage by randomizing intermediate values, which helps thwart power-based attacks but doesn’t inherently fix timing variations. Key rotation and public-key cryptography aren’t measures aimed at reducing leakage from timing or power; they address other security goals like limiting exposure if a key is compromised or enabling secure communication, not side-channel leakage defenses.