# Keeping the Smart Home Private with Smart(er) IoT Traffic Shaping

## TL;DR

This paper introduces stochastic traffic padding (STP), a novel privacy-preserving method for smart home IoT devices that significantly impedes traffic analysis by passive observers, outperforming existing defenses.

## Contribution

We propose STP, a new traffic shaping technique that enhances privacy for smart home IoT devices and provide a theoretical analysis of its effectiveness against passive traffic analysis.

## Key findings

- Existing defenses are insufficient against traffic analysis.
- STP effectively obscures user activities with manageable overhead.
- Theoretical bounds quantify STP's privacy guarantees.

## Abstract

The proliferation of smart home Internet of Things (IoT) devices presents unprecedented challenges for preserving privacy within the home. In this paper, we demonstrate that a passive network observer (e.g., an Internet service provider) can infer private in-home activities by analyzing Internet traffic from commercially available smart home devices even when the devices use end-to-end transport-layer encryption. We evaluate common approaches for defending against these types of traffic analysis attacks, including firewalls, virtual private networks, and independent link padding, and find that none sufficiently conceal user activities with reasonable data overhead. We develop a new defense, "stochastic traffic padding" (STP), that makes it difficult for a passive network adversary to reliably distinguish genuine user activities from generated traffic patterns designed to look like user interactions. Our analysis provides a theoretical bound on an adversary's ability to accurately detect genuine user activities as a function of the amount of additional cover traffic generated by the defense technique.