Signal extends encrypted group video calls to 40 people

The messaging app Signal can now support group video chat with 40 participants – up to five – and end-to-end encryption will still be intact.

The non-profit organization behind Signal announced the change Wednesday; end-to-end encryption means that only the participants in the call can see the messages or the video. No one, including the messaging provider, public authorities or hackers, can see the calls unless a participant accepts them in the video session or they snatch your device.

Signal is best known for offering end-to-end encrypted messages. However, the developers behind the app first started working on encrypted group video chat last year during the height of the pandemic, before rolling it out in December last year.

Signals new limit of 40 participants is higher than some competing messaging apps. WhatsApp offers end-to-end encrypted video calls for up to eight participants, for example, while Apple’s FaceTime supports up to 32 people at once.

Zoom on the other hand allows you to host an end-to-end encrypted video session with up to 200 participants, even if users have to go out of their way to enable the encryption option.

If you’re hoping the Signal Foundation can extend the video calls beyond 40 participants, there’s good news: The nonprofit said this could one day be possible.

In a blog post on Wednesday, the Signal Foundation explained that the expansion of the group video calling feature from five participants to 40 involved the creation of servers that can forward the video call to all participants without viewing or modifying the data. In the end, Signalfonden decided to write the computer code for the server from scratch using the programming language Rust.

“It has now served all Signal group calls for 9 months, scaling to 40 participants with ease (maybe more in the future),” the nonprofit wrote. The encryption keys needed to secure the calls also continue to come from user devices, not the servers.

“When a client joins the call, it generates a key and sends it to all other clients of the call via signal messages,” the Signal Foundation added. “When a user joins or leaves the call, each client in the call generates a new key and sends it to all clients in the call. It then starts using this key 3 seconds later.”

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