Question

Which systems use a timestamp?

i) Public-Key Certificates

ii) Public announcements

iii) Publicly available directories

iv) Public-Key authority

(a) i) and ii)

(b) iii) and iv)

(c) i) and iv)

(d) iv) only

I got this question in an interview for job.

The question is from Public Keys and X.509 Certificates-I topic in section Message Authentication Codes, Whirlpool Algorithm and Key Management and Distribution of Cryptograph & Network Security

Answer 1

Right answer is (c) i) and iv)

Explanation: Public announcements and Public Certificates involve the use of timestamps.