Coding With Scrambling, Concatenation, and HARQ for the AWGN Wire-Tap Channel: A Security Gap Analysis (original) (raw)

Increasing Physical Layer Security through Scrambled Codes and ARQ

2011 IEEE International Conference on Communications Workshops (ICC), 2011

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.

Security gap assessment for the fast fading wiretap channel

ICT 2013, 2013

Using the error rate as a metric is useful for assessing the performance of actual transmission schemes from the physical layer security viewpoint. The security gap concept has been used over the additive white Gaussian noise channel as a practical measure for combined reliability and security. In this paper, the definition of security gap is extended to a wire-tap channel with fast fading. Our aim is to show that by introducing scrambling and error correction coding can significantly reduce the required quality difference between the channel of the authorized user and that of the unauthorized one.

Combining artificial noise beam forming and concatenated coding schemes to effectively secure wireless communications

Analog Integrated Circuits and Signal Processing, 2017

In this paper we present a new scheme combining artificial noise beam forming and secrecy coding to strengthen the security of existing wireless communication systems. Artificial noise and beam forming guarantee a radio advantage to legitimate users, enabling the use of our secrecy coding scheme to provide reliability and secrecy. This overall security protocol is compliant with existing widespread radio access technologies and it can be considered as a key-free add-on to improve security of the physical layer of wireless networks. Keywords Physical layer security Á Secrecy coding Á Radio networks Á Radio channel Á Privacy Nevertheless, the design of a practical wiretap code is very challenging: despite numerous theoretical results,

Wireless Information-Theoretic Security - Part II: Practical Implementation

Computing Research Repository, 2006

In Part I of this two-part paper on confidential communication over wireless channels, we studied the fundamental security limits of quasi-static fading channels from the point of view of outage secrecy capacity with perfect and imperfect channel state information. In Part II, we develop a practical secret key agreement protocol for Gaussian and quasi-static fading wiretap channels. The protocol uses a four-step procedure to secure communications: establish common randomness via an opportunistic transmission, perform message reconciliation, establish a common key via privacy amplification, and use of the key. We introduce a new reconciliation procedure that uses multilevel coding and optimized low density parity check codes which in some cases comes close to achieving the secrecy capacity limits established in Part I. Finally, we develop new metrics for assessing average secure key generation rates and show that our protocol is effective in secure key renewal.

Concatenated coding and hybrid automatic repeat request for wiretap channels

IET Communications, 2014

In this study, the authors propose an equivocation scheme for wiretap channels, which is composed of bit-extension mapping, coset coding and hybrid automatic repeat request (HARQ). The inner bit-extension code and outer coset code are used for equivocation of a wiretapper channel, whereas the HARQ scheme is to mitigate noisy errors in a main legitimate channel. These concatenated codes and HARQ are effective and practical for various channel conditions. The average equivocation and the probability of causing imperfect secrecy are analysed for finite codeword lengths. As a function of channel conditions, they investigate the block error rate at the legitimate receiver and the information leakage to the wiretapper. From simulation results, they further determine the minimum requirements of code design for some target values of the 'residual' block error rate and information leakage at maximum retransmission.

A tight estimation of the security gap over the fast fading wiretap channel

2013 9th International Wireless Communications and Mobile Computing Conference (IWCMC), 2013

In this paper, we provide a tight estimation of the security gap for the wiretap channel with fast Rayleigh fading. The error rate has already been used as a practical physical layer security metric, and the security gap has been defined to exploit such a metric over the wiretap channel with additive white Gaussian noise. We study two different approaches for estimating the security gap also over a fast fading wiretap channel. The first approach is quite conservative, and tends to overestimate the security gap. The second approach instead allows to perform a more realistic evaluation, and to highlight the gain achievable through information scrambling and coding, even when both the legitimate receiver and the eavesdropper channels are known only in statistical terms.

Wireless Information-Theoretic Security

IEEE Transactions on Information Theory, 2008

This paper considers the transmission of confidential data over wireless channels. Based on an information-theoretic formulation of the problem, in which two legitimates partners communicate over a quasi-static fading channel and an eavesdropper observes their transmissions through a second independent quasi-static fading channel, the important role of fading is characterized in terms of average secure communication rates and outage probability. Based on the insights from this analysis, a practical secure communication protocol is developed, which uses a four-step procedure to ensure wireless information-theoretic security: (i) common randomness via opportunistic transmission, (ii) message reconciliation, (iii) common key generation via privacy amplification, and (iv) message protection with a secret key. A reconciliation procedure based on multilevel coding and optimized low-density parity-check (LDPC) codes is introduced, which allows to achieve communication rates close to the fundamental security limits in several relevant instances. Finally, a set of metrics for assessing average secure key generation rates is established, and it is shown that the protocol is effective in secure key renewal-even in the presence of imperfect channel state information.

A practical viewpoint on the performance of LDPC codes over the fast Rayleigh fading wire-tap channel

2013 IEEE Symposium on Computers and Communications (ISCC), 2013

In this paper, we carry out a practical assessment of the performance of finite-length LDPC codes over the wiretap channel with fast Rayleigh fading. Classical metrics for physical layer security, like the secrecy capacity, are based on information theoretic arguments, and provide the ultimate security bounds for these schemes. However, it is difficult to design practical schemes, using some specific finite-length code, able to approach such a performance. Then we use a more practical metric, based on the error probability, which allows assessing the performance achieved in terms of both reliability and security over the fast Rayleigh fading wire-tap channel.

Secret message transmission by HARQ with multiple encoding

2014 IEEE International Conference on Communications (ICC), 2014

Secure transmission between two agents, Alice and Bob, over block fading channels can be achieved similarly to conventional hybrid automatic repeat request (HARQ) by letting Alice transmit multiple blocks, each containing an encoded version of the secret message, until Bob informs Alice about successful decoding by a public error-free return channel. In existing literature each block is a differently punctured version of a single codeword generated with a Wyner code that uses a common randomness for all blocks. In this paper instead we propose a more general approach where multiple codewords are generated from independent randomnesses. The class of channels for which decodability and secrecy is ensured is characterized, with derivations for the existence of secret codes. We show in particular that the classes are not a trivial subset (or superset) of those of existing schemes, thus highlighting the novelty of the proposed solution. The result is further confirmed by deriving the average achievable secrecy throughput, thus taking into account both decoding and secrecy outage.