Joon Kui Ahn

BER-Based Physical Layer Security With Finite Codelength: Combining Strong Converse and Error Amplification

A bit-error-rate (BER)-based physical layer security approach is proposed for the finite blocklengths. For secure communication in the sense of high BER, the information-theoretic strong converse is combined with cryptographic error amplification achieved by the substitution permutation networks based on the confusion and diffusion. For the discrete memoryless channels (DMCs), an analytical framework is provided showing the tradeoffs among the finite blocklength, the maximum/minimum possible transmission rates, and the BER requirements for the legitimate receiver and the eavesdropper. In addition, the security gap is analytically studied for the Gaussian channels and the concept is extended to other DMCs including the binary symmetric channels and binary erasure channels.

Secure Polar Coding With REP and XOR Coding

In this letter, we study the secure data communication by polar coding. In polar coding, all bit-channels perfectly polarize when the codelength goes to infinity. With finite and practical codelength, however, many bit-channels do not perfectly polarize and this significantly degrades the secrecy rate. To address this issue, we propose to use repetition (REP) coding and exclusive-or (XOR) coding combined with polar coding. To make the proposed approach practical, we develop simple design methods for REP and XOR codings. Numerical results demonstrate that the proposed secure polar coding improves the secrecy rate and security gap considerably.