A New Secret key Agreement Scheme in a Four-Terminal Network

TL;DR

This paper introduces a new scheme for generating a shared secret key and private keys among three terminals in a network with an external eavesdropper, using correlated sources and a public channel, and derives capacity bounds.

Contribution

It proposes a novel secret and private key agreement scheme for a four-terminal network with an external eavesdropper, providing inner bounds and capacity regions for specific cases.

Findings

Inner bound of secret key-private keys capacity region derived

Single-letter capacity regions obtained for special cases

Scheme enhances secure communication among multiple terminals

Abstract

A new scenario for generating a secret key and two private keys among three Terminals in the presence of an external eavesdropper is considered. Terminals 1, 2 and 3 intend to share a common secret key concealed from the external eavesdropper (Terminal 4) and simultaneously, each of Terminals 1 and 2 intends to share a private key with Terminal 3 while keeping it concealed from each other and from Terminal 4. All four Terminals observe i.i.d. outputs of correlated sources and there is a public channel from Terminal 3 to Terminals 1 and 2. An inner bound of the "secret key-private keys capacity region" is derived and the single letter capacity regions are obtained for some special cases.