packets to retrieve the original ones.
RLNC is a distributed NC scheme and it was pro-
posed to overcome the centralized code allocation
overhead of Linear NC (LNC) (yen Robert Li et al.,
2003). The unreliable multi-hop transmission and
willful intermediate packet mixing make the RLNC
susceptible to various types of security threats, such
as eavesdropping attacks and Byzantine modifications
that can prevent an efficient implementation of the
RLNC. The former can seriously impair the confiden-
tiality while the latter can damage the authentication
of network coded systems. Indeed, active attackers
try to change, delete, or modify the packet contents
by introducing a malicious code, while on the other
hand, passive attackers try to extract the packet con-
tent by traffic analysis or monitoring of unprotected
communications.
In addition to these attacks, the recent schemes of
RLNC are not only able to introduce new attacks, but
also they can make existing attacks more damaging
and potentially destroying the efficiency of the most
traditionally security techniques used in this domain.
These types of attacks affect the confidential-
ity and the authentication of the transmitted pack-
ets (Fathy et al., 2011). These two requirements are
considered as the core of security. Therefore, bene-
fits from the features introduced by RLNC cannot be
assured in practice without building an efficient and
fully secured scheme.
RLNC may be applied in different domains like
the banking or the military systems, where transmis-
sion of sensitive information is a major concern.
To ensure the basic elements of security: confi-
dentiality, authentication and integrity, several tech-
niques of RLNC have been proposed in the literature
(e.g. (Lima et al., 2007), (Zhang et al., 2010)) and au-
thentication (Li et al., 2010)). These techniques are
only interested in achieving security without taking
into consideration in their implementation the energy
consumption, and the computation and communica-
tion overhead, which are also considered as important
issues that should be studied and analyzed.
As we know, there is always a trade-off between se-
curity and complexity. The existing techniques com-
monly agreed on the designing of network coded
that fulfill Shannon security, but with low through-
put, while in our paper, we are interested in building a
secure scheme with being aware of achieving a good
performance level.
In this paper, an efficient and robust authenticated
confidentiality scheme is proposed to ensure the nec-
essary security services for RLNC. Our solution relies
on combining a Hash Message Authentication Code
(HMAC) in a selective manner with a dynamic mix-
ing cipher scheme. Additionally, our confidentiality
scheme presents an efficient solution to (Lima et al.,
2007), since the second GEV is not transmitted and
using a dynamic diffusion layer instead of the AES
block cipher that can reduce the communication over-
head and computation complexity and consequently
the energy consumption.
The security level achieved in our proposed
scheme is similar to the Shannon security level, but
with low complexity due to the use of secret encod-
ing scheme that reduces the computational complex-
ity and minimizes the amount of secret mixing needed
to ensure the confidentiality of RLNC. This leads to
be considered as suitable for real time (live streaming)
applications.
The rest of this paper is organized as follows: In
Section 2, we give a general idea about the exist-
ing scenario of RLNC, and we focus on the method
used by each scenario to achieve the required secu-
rity level. Then, we highlight the weakness points
presented in each technique that prevent it from be-
ing utilized as a standard secured scheme. After that,
in Section 3, our proposed authenticated-confidential
scheme is defined, and the proposed technique used
to construct the invertible dynamic matrix in inte-
ger fields is explained. The Cryptography strength is
shown in Section 4 Finally, a global conclusion about
the work is given in section 5.
2 PRELIMINARY
2.1 Overview of RLNC
In this section, several existing techniques concerning
RLNC are discussed. This discussion allows exam-
ining the implementation of an efficient and secured
scheme by taking into account the advantages of ex-
isting methods and avoiding as much as possible their
vulnerabilities.
First, we start by describing the traditional RLNC in
details and then explaining the important role of the
set of Global Encoding Vector (GEV) that forms the
Global Encoding Matrix (GEM) G to ensure the secu-
rity services. G is a linear transformation represented
by a matrix, and can be considered as a diffusion layer
for the cipher. The encoding process of RLNC con-
sists of two steps: the first step is resumed by the gen-
erating of GEVs, while the second step is resumed
by the formation of modular vector matrix multipli-
cation. If the coefficients are chosen randomly from a
large field, then the resulting matrix is invertible with
high probability, which explains why this approach is
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