What’s that? How does it work?

What is Matrix?

Matrix is an open standard for messaging, similar in usage to WhatsApp, Telegram, etc., but unlike these apps, you don’t need to sign up with the same provider to write with your friends. Think of something like email rather than WhatsApp: you don’t need a Gmail account to write to someone with an @gmail.com address, and the person you’re writing to doesn’t care what program you use to retrieve your messages. It’s the same with Matrix. You can use it from your smartphone, desktop or browser, your messages will always arrive.

Plus, Matrix has all the features you’d expect from a modern messenger:

  • Group chats with any number of participants
  • Easy sharing of images and files
  • End-to-end encryption (optional)
  • Emojis and stickers
  • Voice and video calls

How does Matrix work?

  • You need a client
    As mentioned above, you can choose which software to use to access your Matrix account. The easiest way is to go to element.physik.kit.edu in your browser, where the web application ‘Element’ is installed. Which software can be used depends on your device. Here are a few recommendations that we have already tested:
    • Desktop: Element (for Linux, MacOS and Windows)
    • Andriod: Element
    • iOS: Element
    • There are of course numerous others that you can use. It is important that the client supports login with Shibboleth, unfortunately not all of them do.
  • The login process
    If you are using an external app, you will need to change the ‘Homeserver’ to https://matrix.physik.kit.edu/. Then you should be able to log in via ‘Single Sign-On’. If you are in the browser, just go to the page.
    • You click on ‘Sign in with single sign-on’.

    • You will be taken to the login page of the SCC, enter the login data of your uxxxx account here as usual.

      • If you are using an app that we do not know, you will be asked to confirm that you trust this app. If you do so, click on ‘OK’.
      • If you use Element Desktop on Linux, it may happen with some distributions, that nothing happens after clicking on ‘OK’. In this case copy the link of the ‘OK’ button (which should start with riot://) and execute element-desktop '<complete link>' in the terminal.
    • You confirm that you have read the (very short) privacy policy.

      • Some clients do not show you the privacy notice directly, but you must accept it before you can start chatting. In this case you must accept the invitation to the chat “Bekanntmachungen” (“Announcements”) and click on the link you get there.
    • You are happy and write to your fellow students.

  • Create rooms
    In Matrix every chat is a ‘room’. Direct messages are also rooms in which only two people are in. You can find people in ‘Direct Messages’ with the ‘+’ symbol. If you have already logged on to the server, you should already be in a room: #all. This is the matrix equivalent to physik-l, everybody gets added when they sign up. Of course you can also quit if it gets too much for you.
  • Private vs. public rooms
    When you create a room you can choose if the room should be public. Public rooms can be joined by anyone and everyone can see which public rooms are available. Only members of non-public rooms know about them and you can only join by invitation. Public rooms are therefore ideal to have a common group for a lecture or as an off-topic chat for the whole semester. Private rooms are good if you want to form a study group with only your friends in it or if you want to decide what to give to your fellow students for their birthday.
  • Encrypting rooms
    When you create a room, it is not encrypted for the time being. This has the advantage that you can view the messages again even if you lose your phone, for example, and have not set up a key backup, so it is ideal for public rooms. But it also has a disadvantage: Your messages are not encrypted! To keep your private conversations private, go to the room settings (in Element small cog in the top right corner), select ‘Security & Privacy’ and flip the ‘Encrypted’ switch. Trust is good, encryption is better.
  • Important: No backup, no pity
    You can use the key-backup function to view your encrypted messages on other devices you log on to later. Element will inform you about this function as soon as you have encrypted the first room. If you lose your keys the old messages are lost forever! So: Always make backups.
  • Communities
    In Matrix, communities are groups that are connected beyond a single room. An example would be a semester that has several rooms for different lectures or minor subjects. To keep the usage of rooms and communities consistent, only admins can create rooms. Just ask an admin if you have an idea for a community.
  • Markdown messages
    You can use some Markdown syntax elements in your messages. This is the same format that HedgeDoc uses.