Random Linear Network Codes for Secrecy over Wireless Broadcast Channels

TL;DR

This paper introduces a secure linear network coding scheme for wireless broadcast channels that ensures message secrecy for privileged clients while maintaining low decoding complexity.

Contribution

It presents a novel method combining linear network coding with coefficient hiding to achieve message secrecy in broadcast channels.

Findings

Unprivileged clients cannot obtain meaningful information from coded data.

The proposed method guarantees message secrecy even if unprivileged clients access all transmitted packets.

Decoding complexity remains low at the receiver side.

Abstract

We consider a set of $n$ messages and a group of $k$ clients. Each client is privileged for receiving an arbitrary subset of the messages over a broadcast erasure channel, which generalizes scenario of a previous work. We propose a method for secretly delivering each message to its privileged recipients in a way that each receiver can decode its own messages but not the others'. Our method is based on combining the messages using linear network coding and hiding the decoding coefficients from the unprivileged clients. We provide an information theoretic proof for the secrecy of the proposed method. In particular we show that an unprivileged client cannot obtain any meaningful information even if it holds the entire set of coded data packets transmitted over the channel. Moreover, in our method, the decoding complexity is desirably low at the receiver side.