# Secure Network Coding in the Setting in Which a Non-Source Node May Generate Random Keys

## TL;DR

This paper studies secure network coding where only one non-source node can generate random keys, characterizing the secure communication rate in this intermediate model with an eavesdropper accessing multiple links.

## Contribution

It introduces and analyzes a new model of secure network coding where a non-source node generates keys, extending understanding beyond traditional source-only key generation scenarios.

## Key findings

- Secure rate characterized for the intermediate model.
- Analysis extends to scenarios with non-source key generation.
- Highlights complexity of secure multicast with multiple key-generating nodes.

## Abstract

It is common in the study of secure multicast network coding in the presence of an eavesdropper that has access to $z$ network links, to assume that the source node is the only node that generates random keys. In this setting, the secure multicast rate is well understood. Computing the secure multicast rate, or even the secure unicast rate, in the more general setting in which all network nodes may generate (independent) random keys is known to be as difficult as computing the (non-secure) capacity of multiple-unicast network coding instances --- a well known open problem. This work treats an intermediate model of secure unicast in which only one node can generate random keys, however that node need not be the source node. The secure communication rate for this setting is characterized again with an eavesdropper that has access to $z$ network links.