(a) Illustrate the difference between symmetric and asymmetric encryption, listing an advantages and a disadvantage of each.
(b) What functions should be given by a public key infrastructure (PKI)? Is it possible to operate such an encryption method without a PKI?
(c) Compare between block and stream ciphers.
(d) What do you understand by certificate revocation? When does it occur? When a certificate is revoked, who is responsible for the revocation?