Variable-Length Secret Key Agreement via Random Stopping Time

TL;DR

This paper introduces a new variable-length secret key agreement method that adapts key length to source realizations using random stopping times, inspired by variable-length source coding techniques.

Contribution

It proposes computationally efficient key agreement schemes with a novel variable-length uniformity constraint based on random stopping times.

Findings

Scheme adapts key length to source realizations

Efficient and computationally feasible implementation

Analogous to Huffman coding and Knuth-Yao generator

Abstract

We consider a key agreement setting where two parties observe correlated random sources, and want to agree on a secret key via public discussions. In order to allow the key length to adapt to the realizations of the random sources, we allow the key to be of variable length, subject to a novel variable-length version of the uniformity constraint based on random stopping time. We propose simple, computationally efficient key agreement schemes under the new constraint. The proposed scheme can be considered as the key agreement analogue of variable-length source coding via Huffman coding, and the Knuth-Yao random number generator.