Quantum Tags for the Authentication of Classical Public Messages
Quantum Tags for the Authentication of Classical Public Messages, Proc Conf. on Telecommunications - ConfTele, St Maria da Feira, Portugal, Vol. 09, pp. 000 - 003, May, 2009.
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We propose a quantum-enhanced protocol to authenticate classical messages, with improved se-
curity with respect to the classical scheme introduced by Brassard in 1983. In that protocol, the
shared key is the seed of a pseudo-random generator (PRG) and a hash function is used to create
the authentication tag of a public message. We show that a quantum encoding of secret bits oﬀers
more security than the classical XOR function introduced by Brassard. Furthermore, we prove that
quantum resources can improve both the secrecy of the key generated by the PRG and the secrecy
of the tag obtained with a hidden hash function. Finally, we establish the conditions that a general
PRG must satisfy for our quantum-enhanced protocol to yield unconditional security. Our protocol
can be used to authenticate a quantum channel.