End-to-end encryption (E2EE) is now also possible with Signal for conference calls with up to 40 participants.
The basics in brief
- Signal conference calls are now encrypted for up to 40 call participants.
- So-called selective forwarding modules make this possible.
Signal encrypts conference calls with up to five participants for about a year. so called End-to-end encryption (E2EE) is now possible with up to 40 participants.
This works thanks to what are called Selective Forwarding Units (SFUs). In a conference call, each participant must distribute audio and video to all other participants in the call. There are 3 possible generic constructs for this, like sign He announces on his blog:
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Each hub sends its media (audio and video) directly to every other hub. This works for very small calls, but cannot be passed on to many participants. Most people don’t have an internet connection fast enough to send 40 copies of their video at a time.
Each participant sends its media to the server. The server “mixes” the media together and sends it to each participant. This works for many participants, but is not compatible with end-to-end encryption. This is because the server must be able to view and change the media.
Each participant sends its media to the server. The server “redirects” the media to other participants without viewing or changing it. This works with multiple participants and is compatible with end-to-end encryption.
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