186 research outputs found
Adaptive Encryption Techniques In Wireless Communication Channels With Tradeoffs Between Communication Reliability And Security
Encryption is a vital process to ensure the confidentiality of the information transmitted over an insecure wireless channel. However, the nature of the wireless channel tends to deteriorate because of noise, interference and fading. Therefore, a symmetrically encrypted transmitted signal will be received with some amount of error. Consequently, due to the strict avalanche criterion (sac), this error propagates during the decryption process, resulting in half the bits (on average) after decryption to be in error. In order to alleviate this amount of error, smart coding techniques and/or new encryption algorithms that take into account the nature of wireless channels are required. The solution for this problem could involve increasing the block and key lengths which might degrade the throughput of the channel. Moreover, these solutions might significantly increase the complexity of the encryption algorithms and hence to increase the cost of its implementation and use. Two main approaches have been folloto solve this problem, the first approach is based on developing an effective coding schemes and mechanisms, in order to minimize and correct the errors introduced by the channel. The second approach is more focused on inventing and implementing new encryption algorithms that encounter less error propagation, by alleviating the sac effect. Most of the research done using these two approaches lacked the comprehensiveness in their designs. Some of these works focused on improving the error performance and/or enhancing the security on the cost of complexity and throughput. In this work, we focus on solving the problem of encryption in wireless channels in a comprehensive way that considers all of the factors in its structure (error performance, security and complexity). New encryption algorithms are proposed, which are modifications to the standardized encryption algorithms and are shown to outperform the use of these algorithms in wireless channels in terms of security and error performance with a slight addition in the complexity. We introduce new modifications that improve the error performance for a certain required security level while achieving the highest possible throughput. We show how our proposed algorithm outperforms the use of other encryption algorithms in terms of the error performance, throughput, complexity, and is secure against all known encryption attacks. In addition, we study the effect of each round and s-box in symmetric encryption algorithms on the overall probability of correct reception at the receiver after encryption and the effect on the security is analyzed as well. Moreover, we perform a complete security, complexity and energy consumption analysis to evaluate the new developed encryption techniques and procedures. We use both analytical computations and computer simulations to evaluate the effectiveness of every modification we introduce in our proposed designs
A Novel Seed Based Random Interleaving for OFDM System and Its PHY Layer Security Implications
Wireless channels are characterized by multipath and fading that can often cause long
burst of errors. Even though, to date, many very sophisticated error correcting codes have
been designed, yet none can handle long burst of errors efficiently. An interleaver, a
device that distributes a burst of errors, possibly caused by a deep fade, and makes them
appear as simple random errors, therefore, proves to a very useful technique when used in
conjunction with an efficient error correcting code.
In this work, a novel near optimal seed based random interleaver is designed. An optimal
interleaver scatters a given burst of errors uniformly over a fixed block of data - a
property that is measured by so called ‘spread’. The design makes use of a unique seed
based pseudo-random sequence generator or logistic map based chaotic sequence
generator to scramble the given block of data. Since the proposed design is based on a
seed based scrambler, the nature of input is irrelevant. Therefore, the proposed interleaver
can interleave either the bits or the symbols or the packets or even the frames.
Accordingly, in this work, we analyze the suitability of interleaver when introduced
before or after the modulation in single carrier communication systems and show that
interleaving the bits before modulation or interleaving the symbols after modulation has
same advantage. We further show that, in an orthogonal frequency division multiplexing
(OFDM) systems, the position of interleaver, whether before or after constellation
mapper, has no significance, and is interchangeable. However, scrambling symbols is
computationally less expensive than scrambling bits.
For the purpose of analyzing the performance of the proposed seed based random
interleaver, simulations are carried out in MATLAB®. Results show that our proposed
seed based random interleaver has near optimal properties of ‘spread’ and ‘dispersion’.
Furthermore, the proposed interleaver is evaluated in terms of bit error rate (BER) versus
length of burst error in a single carrier system both before and after modulation. The
proposed interleaver out-performs the built in RANDINTLV in MATLAB® when used in
the same system. It shows that proposed interleaver can convert greater amount of burst
errors into simple random errors than that of MATLAB® interleaver. The proposed
interleaver is also tested in IEEE 802.16e based WiMAX system with Stanford University Interim (SUI) channels to compare the performance of average BER versus
SNR for both pre modulation and post modulation interleaver. Results show that pre
modulation interleaver and post modulation has same performance.
There is also a side advantage of this seed based interleaver, in that it generates a variety
of unique random-looking interleaving sequences. Only a receiver that has the knowledge
of the input seed can generate this sequence and no one else. If the interleaving patterns
are kept secure then it can possibly be used to introduce an extra layer of security at
physical (PHY) layer. In that way, at PHY layer, one builds an additional entry barrier to
break through and it comes with no extra cost. This property has been investigated by
carrying out key sensitivity analysis to show that the attacks to guess key can be very
futile, as difference at 4th decimal place in the initial condition can lead to entirely
different scrambling
Centralized and Cooperative Transmission of Secure Multiple Unicasts using Network Coding
We introduce a method for securely delivering a set of messages to a group of
clients over a broadcast erasure channel where each client is interested in a
distinct message. Each client is able to obtain its own message but not the
others'. In the proposed method the messages are combined together using a
special variant of random linear network coding. Each client is provided with a
private set of decoding coefficients to decode its own message. Our method
provides security for the transmission sessions against computational
brute-force attacks and also weakly security in information theoretic sense. As
the broadcast channel is assumed to be erroneous, the missing coded packets
should be recovered in some way. We consider two different scenarios. In the
first scenario the missing packets are retransmitted by the base station
(centralized). In the second scenario the clients cooperate with each other by
exchanging packets (decentralized). In both scenarios, network coding
techniques are exploited to increase the total throughput. For the case of
centralized retransmissions we provide an analytical approximation for the
throughput performance of instantly decodable network coded (IDNC)
retransmissions as well as numerical experiments. For the decentralized
scenario, we propose a new IDNC based retransmission method where its
performance is evaluated via simulations and analytical approximation.
Application of this method is not limited to our special problem and can be
generalized to a new class of problems introduced in this paper as the
cooperative index coding problem
A Novel Seed Based Random Interleaving for OFDM System and Its PHY Layer Security Implications
Wireless channels are characterized by multipath and fading that can often cause long
burst of errors. Even though, to date, many very sophisticated error correcting codes have
been designed, yet none can handle long burst of errors efficiently. An interleaver, a
device that distributes a burst of errors, possibly caused by a deep fade, and makes them
appear as simple random errors, therefore, proves to a very useful technique when used in
conjunction with an efficient error correcting code.
In this work, a novel near optimal seed based random interleaver is designed. An optimal
interleaver scatters a given burst of errors uniformly over a fixed block of data - a
property that is measured by so called 'spread'. The design makes use of a unique seed
based pseudo-random sequence generator or logistic map based chaotic sequence
generator to scramble the given block of data. Since the proposed design is based on a
seed based scrambler, the nature of input is irrelevant. Therefore, the proposed interleaver
can interleave either the bits or the symbols or the packets or even the frames.
Accordingly, in this work, we analyze the suitability of interleaver when introduced
before or after the modulation in single carrier communication systems and show that
interleaving the bits before modulation or interleaving the symbols after modulation has
same advantage. We further show that, in an orthogonal frequency division multiplexing
(OFDM) systems, the position of interleaver, whether before or after constellation
mapper, has no significance, and is interchangeable. However, scrambling symbols is
computationally less expensive than scrambling bits.
For the purpose of analyzing the performance of the proposed seed based random
interleaver, simulations are carried out in MA TLAB®. Results show that our proposed
seed based random interleaver has near optimal properties of 'spread' and 'dispersion'.
Furthermore, the proposed interleaver is evaluated in terms of bit error rate (BER) versus
length of burst error in a single carrier system both before and after modulation. The
proposed interleaver out-performs the built in RANDINTLV in MA TLAB® when used in
the same system. It shows that proposed inter Ieaver can convert greater amount of burst
errors into simple random errors than that of MA TLAB® interleaver. The proposed
interleaver is also tested in IEEE 802.16e based WiMAX system with Stanford University Interim (SUI) channels to compare the performance of average BER versus
SNR for both pre modulation and post modulation interleaver. Results show that pre
modulation interleaver and post modulation has same performance.
There is also a side advantage of this seed based interleaver, in that it generates a variety
of unique random-looking interleaving sequences. Only a receiver that has the knowledge
of the input seed can generate this sequence and no one else. If the interleaving patterns
are kept secure then it can possibly be used to introduce an extra layer of security at
physical (PHY) layer. In that way, at PHY layer, one builds an additional entry barrier to
break through and it comes with no extra cost. This property has been investigated by
carrying out key sensitivity analysis to show that the attacks to guess key can be very
futile, as difference at 41
h decimal place in the initial condition can lead to entirely
different scrambling
A Novel Seed Based Random Interleaving for OFDM System and Its PHY Layer Security Implications
Wireless channels are characterized by multipath and fading that can often cause long
burst of errors. Even though, to date, many very sophisticated error correcting codes have
been designed, yet none can handle long burst of errors efficiently. An interleaver, a
device that distributes a burst of errors, possibly caused by a deep fade, and makes them
appear as simple random errors, therefore, proves to a very useful technique when used in
conjunction with an efficient error correcting code.
In this work, a novel near optimal seed based random interleaver is designed. An optimal
interleaver scatters a given burst of errors uniformly over a fixed block of data - a
property that is measured by so called ‘spread’. The design makes use of a unique seed
based pseudo-random sequence generator or logistic map based chaotic sequence
generator to scramble the given block of data. Since the proposed design is based on a
seed based scrambler, the nature of input is irrelevant. Therefore, the proposed interleaver
can interleave either the bits or the symbols or the packets or even the frames.
Accordingly, in this work, we analyze the suitability of interleaver when introduced
before or after the modulation in single carrier communication systems and show that
interleaving the bits before modulation or interleaving the symbols after modulation has
same advantage. We further show that, in an orthogonal frequency division multiplexing
(OFDM) systems, the position of interleaver, whether before or after constellation
mapper, has no significance, and is interchangeable. However, scrambling symbols is
computationally less expensive than scrambling bits.
For the purpose of analyzing the performance of the proposed seed based random
interleaver, simulations are carried out in MATLAB®. Results show that our proposed
seed based random interleaver has near optimal properties of ‘spread’ and ‘dispersion’.
Furthermore, the proposed interleaver is evaluated in terms of bit error rate (BER) versus
length of burst error in a single carrier system both before and after modulation. The
proposed interleaver out-performs the built in RANDINTLV in MATLAB® when used in
the same system. It shows that proposed interleaver can convert greater amount of burst
errors into simple random errors than that of MATLAB® interleaver. The proposed
interleaver is also tested in IEEE 802.16e based WiMAX system with Stanford University Interim (SUI) channels to compare the performance of average BER versus
SNR for both pre modulation and post modulation interleaver. Results show that pre
modulation interleaver and post modulation has same performance.
There is also a side advantage of this seed based interleaver, in that it generates a variety
of unique random-looking interleaving sequences. Only a receiver that has the knowledge
of the input seed can generate this sequence and no one else. If the interleaving patterns
are kept secure then it can possibly be used to introduce an extra layer of security at
physical (PHY) layer. In that way, at PHY layer, one builds an additional entry barrier to
break through and it comes with no extra cost. This property has been investigated by
carrying out key sensitivity analysis to show that the attacks to guess key can be very
futile, as difference at 4th decimal place in the initial condition can lead to entirely
different scrambling
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201
Revisiting Lightweight Encryption for IoT Applications: Error Performance and Throughput in Wireless Fading Channels with and without Coding
© 2013 IEEE. Employing heavy conventional encryption algorithms in communications suffers from added overhead and processing time delay; and in wireless communications, in particular, suffers from severe performance deterioration (avalanche effect) due to fading. Consequently, a tremendous reduction in data throughput and increase in complexity and time delay may occur especially when information traverse resource-limited devices as in Internet-of-Things (IoT) applications. To overcome these drawbacks, efficient lightweight encryption algorithms have been recently proposed in literature. One of those, that is of particular interest, requires using conventional encryption only for the first block of data in a given frame being transmitted. All the information in the remaining blocks is transmitted securely without the need for using heavy conventional encryption. Unlike the conventional encryption algorithms, this particular algorithm achieves lower overhead/complexity and higher data throughput. Assuming the additive white Gaussian noise (AWGN) channel, the performance of the lightweight encryption algorithm under study had been evaluated in literature in terms of throughput under the assumption that the first block, that undergoes conventional encryption, is free of error, which is practically unfeasible. In this paper, we consider the AWGN channel with Rayleigh fading and assume that the signal experiences a certain channel bit error probability and investigate the performance of the lightweight encryption algorithm under study in terms of bit error probability and throughput. We derive analytical expressions for these performance metrics considering modulated signals with and without coding. In addition, we propose an extension to the lightweight encryption algorithm under study by further enhancing its security level without significantly affecting the overhead size and processing time. Via numerical results we show the superiority of the lightweight encryption algorithm under study over the conventional encryption algorithms (like the AES) and the lightweight encryption algorithms proposed in literature in terms of error and throughput performance
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