Which option best describes Kerckhoffs's principle?

• A. The security relies on the key, not secrecy of the algorithm
• B. Kerckhoffs's principle
• C. Security relies on the secrecy of the algorithm
• D. Security relies on hardware security

Answer: (B)

Security relies on the key, not secrecy of the algorithm. Kerckhoffs's principle says a cryptosystem should remain secure even if everything about the method is known except the key. This means the algorithm can be public, well studied, and analyzed by anyone, and the only secret that protects messages is the cryptographic key. Designing this way keeps security robust against secrecy failures and emphasizes strong key management and adequate key lengths. The other options describe either hiding the algorithm or relying on hardware, which doesn’t capture the essential idea that security should depend on the key, not on keeping the method secret.