Analysis of Short Blocklength Codes for Secrecy

TL;DR

This paper introduces new secrecy metrics for physical-layer coding with finite blocklengths, providing probabilistic error guarantees and aiding practical system design for secure communications over Gaussian and fading channels.

Contribution

It develops novel secrecy metrics that extend beyond traditional measures, enabling probabilistic guarantees and simplifying complex channel models for security code design.

Findings

New secrecy metrics with probabilistic error guarantees

Metrics applicable to Gaussian and fading wiretap channels

Facilitates practical design of physical-layer security codes

Abstract

In this paper we provide secrecy metrics applicable to physical-layer coding techniques with finite blocklengths over Gaussian and fading wiretap channel models. Our metrics go beyond some of the known practical secrecy measures, such as bit error rate and security gap, so as to make lower bound probabilistic guarantees on error rates over short blocklengths both preceding and following a secrecy decoder. Our techniques are especially useful in cases where application of traditional information-theoretic security measures is either impractical or simply not yet understood. The metrics can aid both practical system analysis, and practical system design for physical-layer security codes. Furthermore, these new measures fill a void in the current landscape of practical security measures for physical-layer security coding, and may assist in the wide-scale adoption of physical-layer techniques for security in real-world systems. We also show how the new metrics provide techniques for reducing realistic channel models to simpler discrete memoryless wiretap channel equivalents over which existing secrecy code designs may achieve information-theoretic security.