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Information-theoretic Physical Layer Security for Satellite Channels
Shannon introduced the classic model of a cryptosystem in 1949, where Eve has
access to an identical copy of the cyphertext that Alice sends to Bob. Shannon
defined perfect secrecy to be the case when the mutual information between the
plaintext and the cyphertext is zero. Perfect secrecy is motivated by
error-free transmission and requires that Bob and Alice share a secret key.
Wyner in 1975 and later I.~Csisz\'ar and J.~K\"orner in 1978 modified the
Shannon model assuming that the channels are noisy and proved that secrecy can
be achieved without sharing a secret key. This model is called wiretap channel
model and secrecy capacity is known when Eve's channel is noisier than Bob's
channel.
In this paper we review the concept of wiretap coding from the satellite
channel viewpoint. We also review subsequently introduced stronger secrecy
levels which can be numerically quantified and are keyless unconditionally
secure under certain assumptions. We introduce the general construction of
wiretap coding and analyse its applicability for a typical satellite channel.
From our analysis we discuss the potential of keyless information theoretic
physical layer security for satellite channels based on wiretap coding. We also
identify system design implications for enabling simultaneous operation with
additional information theoretic security protocols
Secure Satellite Communication Systems Design with Individual Secrecy Rate Constraints
In this paper, we study multibeam satellite secure communication through
physical (PHY) layer security techniques, i.e., joint power control and
beamforming. By first assuming that the Channel State Information (CSI) is
available and the beamforming weights are fixed, a novel secure satellite
system design is investigated to minimize the transmit power with individual
secrecy rate constraints. An iterative algorithm is proposed to obtain an
optimized power allocation strategy. Moreover, sub-optimal beamforming weights
are obtained by completely eliminating the co-channel interference and nulling
the eavesdroppers' signal simultaneously. In order to obtain jointly optimized
power allocation and beamforming strategy in some practical cases, e.g., with
certain estimation errors of the CSI, we further evaluate the impact of the
eavesdropper's CSI on the secure multibeam satellite system design. The
convergence of the iterative algorithm is proven under justifiable assumptions.
The performance is evaluated by taking into account the impact of the number of
antenna elements, number of beams, individual secrecy rate requirement, and
CSI. The proposed novel secure multibeam satellite system design can achieve
optimized power allocation to ensure the minimum individual secrecy rate
requirement. The results show that the joint beamforming scheme is more
favorable than fixed beamforming scheme, especially in the cases of a larger
number of satellite antenna elements and higher secrecy rate requirement.
Finally, we compare the results under the current satellite air-interface in
DVB-S2 and the results under Gaussian inputs.Comment: 34 pages, 10 figures, 1 table, submitted to "Transactions on
Information Forensics and Security
Authentication of Satellite Navigation Signals by Wiretap Coding and Artificial Noise
In order to combat the spoofing of global navigation satellite system (GNSS)
signals we propose a novel approach for satellite signal authentication based
on information-theoretic security. In particular we superimpose to the
navigation signal an authentication signal containing a secret message
corrupted by artificial noise (AN), still transmitted by the satellite. We
impose the following properties: a) the authentication signal is synchronous
with the navigation signal, b) the authentication signal is orthogonal to the
navigation signal and c) the secret message is undecodable by the attacker due
to the presence of the AN. The legitimate receiver synchronizes with the
navigation signal and stores the samples of the authentication signal with the
same synchronization. After the transmission of the authentication signal,
through a separate public asynchronous authenticated channel (e.g., a secure
Internet connection) additional information is made public allowing the
receiver to a) decode the secret message, thus overcoming the effects of AN,
and b) verify the secret message. We assess the performance of the proposed
scheme by the analysis of both the secrecy capacity of the authentication
message and the attack success probability, under various attack scenarios. A
comparison with existing approaches shows the effectiveness of the proposed
scheme
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