On Secrecy above Secrecy Capacity

TL;DR

This paper explores the secrecy of Gaussian Wiretap channels when transmitting above the secrecy capacity, using probability of error as a secrecy measure, and finds that confusion levels are similar to those below capacity.

Contribution

It introduces a new perspective on secrecy above capacity by focusing on error probability rather than equivocation, showing that standard codes can achieve high secrecy.

Findings

Secrecy can be maintained above the secrecy capacity using standard codes.

Confusion caused to eavesdropper is similar above and below capacity.

Transmission rates can reach the channel capacity while preserving secrecy.

Abstract

We consider secrecy obtained when one transmits on a Gaussian Wiretap channel above the secrecy capacity. Instead of equivocation, we consider probability of error as the criterion of secrecy. The usual channel codes are considered for transmission. The rates obtained can reach the channel capacity. We show that the "confusion" caused to the Eve when the rate of transmission is above capacity of the Eve's channel is similar to the confusion caused by using the wiretap channel codes used below the secrecy capacity.