---
type: entity
title: Matrix
tags: [protocol, communication, chat, decentralized, instant-messaging]
related: [instant-messaging, universitatsrechenzentrum-urz, element, ums, shibboleth, matrix-home-server, matrix-id, matrix-datenschutz]
created: 2026-06-30
updated: 2026-06-30
sources: ["output/rz_uni_greifswald_de_dienste_allgemein_instant_messaging_chat.md", "output/rz_uni_greifswald_de_dienste_allgemein_instant_messaging_chat_matrix.md", "output/rz_uni_greifswald_de_dienste_allgemein_instant_messaging_chat_matrix_anmelden.md", "output/rz_uni_greifswald_de_dienste_allgemein_instant_messaging_chat_matrix_datenschutz.md"]
---

# Matrix

**Matrix** is a modern, decentralized communication protocol and platform provided by the [[universitatsrechenzentrum-urz]] for both internal and external instant messaging and (video) calls. It is one of the two instant messaging platforms provided by the [[universitatsrechenzentrum-urz]] for real-time communication within the university's [[campus-it]] infrastructure.

## Service Characteristics
- **Decentralization**: Supports federation, allowing communication with users on other Matrix servers.
- **Security**: Supports End-to-End Encryption (E2EE) for 1:1 and group conversations.
- **Access**: Requires explicit consent via the account management system and authentication via Shibboleth.

## Implementation at Universität Greifswald
The URZ operates its own [[matrix-home-server]] at `matrix.uni-greifswald.de`, which is integrated into the worldwide Matrix network.

### Access and Prerequisites
To use the service, university members must fulfill the following requirements:
- **Consent**: Users must grant a consent declaration through the [[ums]].
- **Authentication**: Access is provided via [[shibboleth]] using their [[zentraler-nutzeraccount]].

### Identity and Clients
- **Identity**: Users are identified by a unique [[matrix-id]] (MXID).
- **Recommended Clients**: The URZ recommends using [[element]] as the primary client for interacting with the Matrix network (specifically [[element-classic]] for mobile).

### Security Features
- **Encryption**: The platform utilizes encrypted client-server connections and implements End-to-End Encryption (E2EE) as the standard for 1:1 and group conversations.
- **Security Keys**: Users must configure a security key for their Matrix ID to facilitate encrypted communication.
- **Sensitive Data**: Due to its security architecture, the URZ recommends Matrix for exchanging sensitive information. For comparison, the URZ explicitly advises against the use of external services like Skype for such tasks.

## Privacy and Data Retention
The service operates under strict privacy guidelines to ensure [[gdpr-compliance]]:
- **Log Retention**: System logs are deleted after 7 days.
- **Room Persistence**: Data in a chat room is only deleted from the university server once all participants have left the room.
- **Data Sovereignty**: While the URZ manages the internal server, [[federated-data-storage]] means that data sent to external partners is subject to the policies of those external servers.
- **Account Deletion**: Most personal data is removed upon account deletion, though the [[matrix-id]] remains as an anonymized identifier.