Classical Encryption and Authentication under Quantum Attacks
Maria Velema

Abstract:
Post-quantum cryptography studies the security of classical,
i.e. non-quantum cryptographic protocols against quantum
attacks. Until recently, the considered adversaries were assumed to
use quantum computers and behave like classical adversaries
otherwise. A more conservative approach is to assume that also the
communication between the honest parties and the adversary is (partly)
quantum. We discuss several options to define secure encryption and
authentication against these stronger adversaries who can carry out
superposition attacks. We re-prove a recent result of Boneh and
Zhandry, stating that a uniformly random function (and hence also a
quantum-secure pseudorandom function) can serve as a
message-authentication code which is secure, even if the adversary can
evaluate this function in superposition.