Question

Which Authentication Encryption approach is taken by the IPSec protocol?

(a) Authentication followed by encryption (A→E)

(b) Hashing followed by encryption (H→E)

(c) Encryption followed by authentication (E→A)

(d) Independently encrypt and authenticate (E + A)

The question was posed to me by my school teacher while I was bunking the class.

My doubt is from CCM, GCM and Key Wrapping in chapter Message Authentication Codes, Whirlpool Algorithm and Key Management and Distribution of Cryptograph & Network Security

Answer 1

Right answer is (c) Encryption followed by authentication (E→A)

Explanation: Encryption followed by authentication (E→A) is the AE approach taken by the IPSec protocol.