Abstract
In order to secure wireless communications, we consider the usage of physical-layer security (PLS) mechanisms (i.e., coding for secrecy mechanisms) combined with self-interference generation. We present a prototype implementation of a scrambled coding for secrecy mechanisms with interference generation by the legitimate receiver and the cancellation of the effect of self-interference (SI). Regarding the SI cancellation, four state-of-the-art algorithms were considered: Least mean square (LMS), normalized least mean square (NLMS), recursive least squares (RLS) and QR decomposition recursive least squares (QRDRLS). The prototype implementation is performed in real-world software-defined radio (SDR) devices using GNU-Radio, showing that the LMS outperforms all other algorithms considered (NLMS, RLS and QRDRLS), being the best choice to use in this situation (SI cancellation). It was also shown that it is possible to secure communication using only noise generation by the legitimate receiver, though a variation of the packet loss rate (PLR) and the bit error rate (BER) gaps is observed when moving from the fairest to an advantageous or a disadvantageous scenario. Finally, when noise generation was combined with the adapted scrambled coding for secrecy with a hidden key scheme, a noteworthy security improvement was observed resulting in an increased BER for Eve with minor interference to Bob.
Highlights
Secrecy against eavesdroppers has always been a concern in communication systems.This threat is relevant in wireless communications where, due to their broadcast nature, it is difficult to restrict the communication to an intended receiver (Bob) while guaranteeing secrecy against an illegitimate one (Eve) [1]. 5G and internet-of-things (IoT), with “everything” connected, have just aggravated these concerns [2].Shannon was the first to address the secrecy problem [3] paving the way for the study of information theoretically secure coding schemes
The biggest challenge we faced when using the least mean square (LMS)/normalized least mean square (NLMS)/recursive least squares (RLS)/QR decomposition recursive least squares (QRD-RLS) Filter blocks was that the noisy jamming sample that is mixed with the signal to be input in the second entry must be time aligned with its respective original jamming sample, i.e., both inputs of the adaptive filter need to be synchronized in order to work properly
We presented a software-defined radio (SDR) proof-of-concept implementation in GNU Radio of the SCS-HK coding for secrecy scheme combined with FD jamming interference generated by the legitimate receiver against an unknown eavesdropper
Summary
Secrecy against eavesdroppers has always been a concern in communication systems. This threat is relevant in wireless communications where, due to their broadcast nature, it is difficult to restrict the communication to an intended receiver (Bob) while guaranteeing secrecy against an illegitimate one (Eve) [1]. 5G and internet-of-things (IoT), with “everything” connected, have just aggravated these concerns [2]. Most of these schemes rely on Wyner’s wiretap channel assumption of Eve having a disadvantage with respect to Bob, which is difficult to assure at all times This led to the development of friendly/cooperative jamming schemes where there is one helper node causing interference to degrade Eve’s channel [14,15,16]. In this work we combine coding for secrecy mechanisms with FD interference generation by the legitimate receiver and the cancellation of the effect of SI, and we make a proof-of-concept of this scheme showing it to be possible to secure communication using only noise generated by Bob, even when Bob has a degraded channel with respect to Eve. We consider the use of interleaved/scrambled coding for secrecy with a hidden key (ICS-HK/SCS-HK) [29,30].
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