2 research outputs found
Analysis of Channel-Based User Authentication by Key-Less and Key-Based Approaches
User authentication (UA) supports the receiver in deciding whether a message
comes from the claimed transmitter or from an impersonating attacker. In
cryptographic approaches messages are signed with either an asymmetric or
symmetric key, and a source of randomness is required to generate the key. In
physical layer authentication (PLA) instead the receiver checks if received
messages presumably coming from the same source undergo the same channel. We
compare these solutions by considering the physical-layer channel features as
randomness source for generating the key, thus allowing an immediate comparison
with PLA (that already uses these features). For the symmetric-key approach we
use secret key agreement, while for asymmetric-key the channel is used as
entropy source at the transmitter. We focus on the asymptotic case of an
infinite number of independent and identically distributed channel
realizations, showing the correctness of all schemes and analyzing the secure
authentication rate, that dictates the rate at which the probability that UA
security is broken goes to zero as the number of used channel resources (to
generate the key or for PLA) goes to infinity. Both passive and active attacks
are considered and by numerical results we compare the various systems
Pilot Contamination Attack Detection by Key-Confirmation in Secure MIMO Systems
Many security techniques working at the physical layer need a correct channel
state information (CSI) at the transmitter, especially when devices are
equipped with multiple antennas. Therefore such techniques are vulnerable to
pilot contamination attacks (PCAs) by which an attacker aims at inducing false
CSI. In this paper we provide a solution to some PCA methods, by letting two
legitimate parties to compare their channel estimates. The comparison is made
in order to minimize the information leakage on the channel to a possible
attacker. By reasonable assumptions on both the channel knowledge by the
attacker and the correlation properties of the attacker and legitimate channels
we show the validity of our solution. An accurate analysis of possible attacks
and countermeasures is provided, together with a numerical evaluation of the
attainable secrecy outage probability when our solution is used in conjunction
with beamforming for secret communications.Comment: accepted, appears in IEEE GLOBECOM 201