Unshared Secret Key Cryptography: Finite Constellation Inputs and Ideal Secrecy Outage

TL;DR

This paper introduces a practical USK cryptography scheme using finite constellations and cooperative jamming, achieving ideal secrecy with minimal outage probability even when eavesdroppers have more antennas.

Contribution

It extends USK cryptography to finite constellations and practical scenarios, enabling ideal secrecy without secret key exchange in MIMO wiretap channels.

Findings

Achieves Shannon's ideal secrecy with small outage probability.

Valid for eavesdroppers with more antennas than the transmitter.

Uses cooperative jamming to enhance security.

Abstract

The Unshared Secret Key Cryptography (USK), recently proposed by the authors, guarantees Shannon's ideal secrecy and perfect secrecy for MIMO wiretap channels, without requiring secret key exchange. However, the requirement of infinite constellation inputs limits its applicability to practical systems. In this paper, we propose a practical USK scheme using finite constellation inputs. The new scheme is based on a cooperative jamming technique, and is valid for the case where the eavesdropper has more antennas than the transmitter. We show that Shannon's ideal secrecy can be achieved with an arbitrarily small outage probability.