3,248 research outputs found
Coding with Scrambling, Concatenation, and HARQ for the AWGN Wire-Tap Channel: A Security Gap Analysis
This study examines the use of nonsystematic channel codes to obtain secure
transmissions over the additive white Gaussian noise (AWGN) wire-tap channel.
Unlike the previous approaches, we propose to implement nonsystematic coded
transmission by scrambling the information bits, and characterize the bit error
rate of scrambled transmissions through theoretical arguments and numerical
simulations. We have focused on some examples of Bose-Chaudhuri-Hocquenghem
(BCH) and low-density parity-check (LDPC) codes to estimate the security gap,
which we have used as a measure of physical layer security, in addition to the
bit error rate. Based on a number of numerical examples, we found that such a
transmission technique can outperform alternative solutions. In fact, when an
eavesdropper (Eve) has a worse channel than the authorized user (Bob), the
security gap required to reach a given level of security is very small. The
amount of degradation of Eve's channel with respect to Bob's that is needed to
achieve sufficient security can be further reduced by implementing scrambling
and descrambling operations on blocks of frames, rather than on single frames.
While Eve's channel has a quality equal to or better than that of Bob's
channel, we have shown that the use of a hybrid automatic repeat-request (HARQ)
protocol with authentication still allows achieving a sufficient level of
security. Finally, the secrecy performance of some practical schemes has also
been measured in terms of the equivocation rate about the message at the
eavesdropper and compared with that of ideal codes.Comment: 29 pages, 10 figure
Increasing Physical Layer Security through Scrambled Codes and ARQ
We develop the proposal of non-systematic channel codes on the AWGN wire-tap
channel. Such coding technique, based on scrambling, achieves high transmission
security with a small degradation of the eavesdropper's channel with respect to
the legitimate receiver's channel. In this paper, we show that, by implementing
scrambling and descrambling on blocks of concatenated frames, rather than on
single frames, the channel degradation needed is further reduced. The usage of
concatenated scrambling allows to achieve security also when both receivers
experience the same channel quality. However, in this case, the introduction of
an ARQ protocol with authentication is needed.Comment: 5 pages, 4 figures; Proc. IEEE ICC 2011, Kyoto, Japan, 5-9 June 201
A Physical Layer Secured Key Distribution Technique for IEEE 802.11g Wireless Networks
Key distribution and renewing in wireless local area networks is a crucial
issue to guarantee that unauthorized users are prevented from accessing the
network. In this paper, we propose a technique for allowing an automatic
bootstrap and periodic renewing of the network key by exploiting physical layer
security principles, that is, the inherent differences among transmission
channels. The proposed technique is based on scrambling of groups of
consecutive packets and does not need the use of an initial authentication nor
automatic repeat request protocols. We present a modification of the scrambling
circuits included in the IEEE 802.11g standard which allows for a suitable
error propagation at the unauthorized receiver, thus achieving physical layer
security.Comment: 9 pages, 7 figures. Accepted for publication in IEEE Wireless
Communications Letters. Copyright transferred to IEE
Improving the efficiency of the LDPC code-based McEliece cryptosystem through irregular codes
We consider the framework of the McEliece cryptosystem based on LDPC codes,
which is a promising post-quantum alternative to classical public key
cryptosystems. The use of LDPC codes in this context allows to achieve good
security levels with very compact keys, which is an important advantage over
the classical McEliece cryptosystem based on Goppa codes. However, only regular
LDPC codes have been considered up to now, while some further improvement can
be achieved by using irregular LDPC codes, which are known to achieve better
error correction performance than regular LDPC codes. This is shown in this
paper, for the first time at our knowledge. The possible use of irregular
transformation matrices is also investigated, which further increases the
efficiency of the system, especially in regard to the public key size.Comment: 6 pages, 3 figures, presented at ISCC 201
A class of punctured simplex codes which are proper for error detection
Binary linear [n,k] codes that are proper for error detection are known for
many combinations of n and k. For the remaining combinations, existence of
proper codes is conjectured. In this paper, a particular class of [n,k] codes
is studied in detail. In particular, it is shown that these codes are proper
for many combinations of n and k which were previously unsettled
Progressive Differences Convolutional Low-Density Parity-Check Codes
We present a new family of low-density parity-check (LDPC) convolutional
codes that can be designed using ordered sets of progressive differences. We
study their properties and define a subset of codes in this class that have
some desirable features, such as fixed minimum distance and Tanner graphs
without short cycles. The design approach we propose ensures that these
properties are guaranteed independently of the code rate. This makes these
codes of interest in many practical applications, particularly when high rate
codes are needed for saving bandwidth. We provide some examples of coded
transmission schemes exploiting this new class of codes.Comment: 8 pages, 2 figures. Accepted for publication in IEEE Communications
Letters. Copyright transferred to IEE
A dyadic model on a tree
We study an infinite system of non-linear differential equations coupled in a
tree-like structure. This system was previously introduced in the literature
and it is the model from which the dyadic shell model of turbulence was
derived. It mimics 3d Euler and Navier-Stokes equations in a rough
approximation of a wavelet decomposition. We prove existence of finite energy
solutions, anomalous dissipation in the inviscid unforced case, existence and
uniqueness of stationary solutions (either conservative or not) in the forced
case
Advanced channel coding for space mission telecommand links
We investigate and compare different options for updating the error
correcting code currently used in space mission telecommand links. Taking as a
reference the solutions recently emerged as the most promising ones, based on
Low-Density Parity-Check codes, we explore the behavior of alternative schemes,
based on parallel concatenated turbo codes and soft-decision decoded BCH codes.
Our analysis shows that these further options can offer similar or even better
performance.Comment: 5 pages, 7 figures, presented at IEEE VTC 2013 Fall, Las Vegas, USA,
Sep. 2013 Proc. IEEE Vehicular Technology Conference (VTC 2013 Fall), ISBN
978-1-6185-9, Las Vegas, USA, Sep. 201
Stochastic Navier-Stokes Equations and Related Models
Regularization by noise for certain classes of fluid dynamic equations, a
theme dear to Giuseppe Da Prato (see G. Da Prato and A. Debussche, Ergodicity
for the 3D stochastic Navier-Stokes equations, J. Math. Pures Appl., 2003), is
reviewed focusing on 3D Navier-Stokes equations and dyadic models of
turbulence
Security and complexity of the McEliece cryptosystem based on QC-LDPC codes
In the context of public key cryptography, the McEliece cryptosystem
represents a very smart solution based on the hardness of the decoding problem,
which is believed to be able to resist the advent of quantum computers. Despite
this, the original McEliece cryptosystem, based on Goppa codes, has encountered
limited interest in practical applications, partly because of some constraints
imposed by this very special class of codes. We have recently introduced a
variant of the McEliece cryptosystem including low-density parity-check codes,
that are state-of-the-art codes, now used in many telecommunication standards
and applications. In this paper, we discuss the possible use of a bit-flipping
decoder in this context, which gives a significant advantage in terms of
complexity. We also provide theoretical arguments and practical tools for
estimating the trade-off between security and complexity, in such a way to give
a simple procedure for the system design.Comment: 22 pages, 1 figure. This paper is a preprint of a paper accepted by
IET Information Security and is subject to Institution of Engineering and
Technology Copyright. When the final version is published, the copy of record
will be available at IET Digital Librar
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