On Secure Communication with Constrained Randomization

TL;DR

This paper explores how constraints on randomization sources impact secrecy capacity in wiretap channels, demonstrating that limited randomness reduces but does not eliminate secure communication, and proposing practical coding schemes.

Contribution

It characterizes secrecy capacity with rate-limited randomness and introduces secure communication methods using non-uniform sources.

Findings

Limited rate randomization incurs a secrecy penalty.

Secure communication remains possible with constrained randomness.

Practical coding schemes can be designed with non-uniform sources.

Abstract

In this paper, we investigate how constraints on the randomization in the encoding process affect the secrecy rates achievable over wiretap channels. In particular, we characterize the secrecy capacity with a rate-limited local source of randomness and a less capable eavesdropper's channel, which shows that limited rate incurs a secrecy rate penalty but does not preclude secrecy. We also discuss a more practical aspect of rate-limited randomization in the context of cooperative jamming. Finally, we show that secure communication is possible with a non-uniform source for randomness; this suggests the possibility of designing robust coding schemes.