# Polar Coding for Common Message Only Wiretap Broadcast Channel

## TL;DR

This paper introduces a novel polar coding scheme for a wiretap broadcast channel that securely delivers the same confidential message to two receivers without assuming channel symmetry or degradedness.

## Contribution

It extends polar coding techniques with a new chaining construction enabling secure, reliable transmission of a common confidential message to multiple receivers in a wiretap setting.

## Key findings

- Achieves secure communication without channel symmetry assumptions
- Introduces a chaining construction for reliable, secure message delivery
- Provides a new analysis of dependencies for secrecy proof

## Abstract

A polar coding scheme is proposed for the Wiretap Broadcast Channel with two legitimate receivers and one eavesdropper. We consider a model in which the transmitter wishes to send a private and a confidential message that must be reliably decoded by the receivers, and the confidential message must also be (strongly) secured from the eavesdropper. The coding scheme aims to use the optimal rate of randomness and does not make any assumption regarding the symmetry or degradedness of the channel. This paper extends previous work on polar codes for the wiretap channel by proposing a new chaining construction that allows to reliably and securely send the same confidential message to two different receivers. This construction introduces new dependencies between the random variables involved in the coding scheme that need to be considered in the secrecy analysis.