User devices

Primary device

• Every user on Comm has a primary device
  • This can either be a cell phone, or a full-fledged keyserver (see below)
• Your primary device owns your private keys and personal data
  • When you send messages to your friends, those messages get stored on their primary device
• Your other devices all "proxy" through your primary device
  • When you send a message on a secondary device, it goes to your primary device first so that it can be signed with your private key
  • When you receive a message on a secondary device, it is initially received on your primary device and then decrypted with your private key, before being forwarded to your secondary devices

Keyservers

• A keyserver is a primary device that can also host communities
  • Keyservers are necessary to host communities because they can handle background processing and respond to queries on-demand
• You can use our desktop app on your laptop (macOS or Windows) to host a keyserver, or you can host a keyserver as a Linux service
• Comm is not able to control who has access to the data on a keyserver
  • For instance, if your friend is hosting a keyserver on a parent's computer, presumably the parent has access to that data
  • Or if you choose to host a kesyerver on a cloud service like AWS, then presumably Amazon has access to that data
• Multiple users can share the same keyserver

Core Concepts

Communities

• Communities in Comm are like servers in Discord
• Each community is hosted on a specific user's keyserver
• Users in Comm can be a member of any number of communities
• You don't need a keyserver to join a community, but you do need one to host a community

Chats

• There are two distinct kinds of chats in Comm:
  • DMs DMs are similar to chats in iMessage, WhatsApp, or Signal. When you send a message to a local thread, your primary device encrypts that message separately for each recipient, and then sends it directly to each recipient.
  • Communities & channels Chats inside a community are called channels, and they are similar to channels in Slack or Discord. When you send a message to a channel, your primary device encrypts that message for the community host's keyserver, and the community host's keyserver handles sending it to participants.
• Because they are hosted on a keyserver, channels are more full-featured than DMs
  • Channels can have complex roles and permissions
  • You can scroll back or search through all of the historical messages of a channel, even if those messages were sent before you joined the channel
  • Channels can have other channels as children

Threads