# PACCART: Reinforcing Trust in Multiuser Privacy Agreement Systems

## TL;DR

PACCART is an open-source agent designed to enhance trust in multiuser privacy agreements by adhering to criteria like concealment, equity, collaboration, and explainability, demonstrated to increase user trust through simulations and user studies.

## Contribution

This paper introduces PACCART, a trustworthy agent that supports multiuser privacy agreements with novel features to improve user trust and address privacy management challenges.

## Key findings

- PACCART significantly increases user trust in privacy agreement systems.
- Simulations and user studies validate the effectiveness of PACCART.
- PACCART adheres to key trust criteria: concealment, equity, collaboration, and explainability.

## Abstract

Collaborative systems, such as Online Social Networks and the Internet of Things, enable users to share privacy sensitive content. Content in these systems is often co-owned by multiple users with different privacy expectations, leading to possible multiuser privacy conflicts. In order to resolve these conflicts, various agreement mechanisms have been designed and agents that could participate in such mechanisms have been proposed. However, research shows that users hesitate to use software tools for managing their privacy. To remedy this, we argue that users should be supported by trustworthy agents that adhere to the following criteria: (i) concealment of privacy preferences, such that only necessary information is shared with others, (ii) equity of treatment, such that different kinds of users are supported equally, (iii) collaboration of users, such that a group of users can support each other in agreement and (iv) explainability of actions, such that users know why certain information about them was shared to reach a decision. Accordingly, this paper proposes PACCART, an open-source agent that satisfies these criteria. Our experiments over simulations and user study indicate that PACCART increases user trust significantly.