Question

In brute force attack, on average half of all possible keys must be tried to achieve success.

(a) True

(b) False

This question was posed to me during an interview.

My doubt is from Symmetric Cipher Models and Elementary Number Theory topic in portion Classical Encryption Techniques of Cryptograph & Network Security

Answer 1

Correct answer is (a) True

Easiest explanation: In brute force attack the attacker tries every possible key on a piece of cipher-text until an intelligible translation into plaintext is obtained.