Low Complex System for Physical Layer Security Using NLFG and QCLDPC Code

In practical communication applications, the channels for intended users and eavesdroppers are not error-free and Wyner’s wiretap channel model deals with the scenario. Using this model, the security of a stand-alone stream cipher can be strengthened by exploiting the properties of physical layer. In this paper, a joint channel coding and light weight cryptography for setting a Gaussian wiretap channel is proposed. The scheme is based on a keyed Quasi Cyclic Low Density Parity Check (QCLDPC) encoder and light weight stream cipher based on Linear Feedback Shift Register (LFSR). The significant contribution is that, highly complex non-linear function that provides security in a Non-Linear Filter Generator (NLFG) is replaced by a simple non-linear function without compromising security. Enhanced security with lesser complexity is achieved by embedding security in channel encoder. Results show that attacker cannot extract the secret key because of the errors introduced in the physical layer due to unknown structure of the channel encoder.