Practical Secrecy: Bridging the Gap between Cryptography and Physical Layer Security

TL;DR

This paper demonstrates that artificial noise in physical layer security can achieve practical and perfect secrecy without secret keys or channel restrictions, bridging cryptography and physical layer security.

Contribution

It introduces a scheme using artificial noise as a one-time pad to achieve practical and perfect secrecy, even against powerful eavesdroppers, without key exchange.

Findings

Artificial noise can provide practical secrecy without key exchange.

Achieving perfect secrecy is easier than non-zero secrecy capacity.

Practical and strong secrecy are maintained even if artificial noise is removed.

Abstract

Current security techniques can be implemented either by requiring a secret key exchange or depending on assumptions about the communication channels. In this paper, we show that, by using a physical layer technique known as artificial noise, it is feasible to protect secret data without any form of secret key exchange and any restriction on the communication channels. Specifically, we analyze how the artificial noise can achieve practical secrecy. By treating the artificial noise as an unshared one-time pad secret key, we show that the proposed scheme also achieves Shannon's perfect secrecy. Moreover, we show that achieving perfect secrecy is much easier than ensuring non-zero secrecy capacity, especially when the eavesdropper has more antennas than the transmitter. Focusing on the practical applications, we show that practical secrecy and strong secrecy can be guaranteed even if the eavesdropper attempts to remove the artificial noise. We finally show the connections between traditional cryptography and physical layer security.