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This whole discussion is about the E2E case. That's what the CEO was referring to. There's a twitter thread link somewhere.

I think I read that Zoom do decrypt AES-GCM server side already. They have to so they can put the little green box around the person currently speaking. EDIT - this is incorrect for AES-GCM, it's not decrypted server side.

Edit - at least e2e is the angle I'm approaching it from as it's the new information.

2 comments

This is what you said:

> Meetings will still be encrypted and meeting content is still not going to be used for tracking users.

And the person responding to you asked "how will you show this?".

Which is a fairly ambiguous question and could be interpreted several ways so I went mainly for the E2E case (as it's the new thing).

Could also be interpreted as how can we show only paid users can access it? Or that certain features will be disabled with E2E?

What I replied with covers both E2E and the current state equally tbh (the linked article did it before with ECB). There are always limitations to what is possible.

I could break into the Zoom servers to make sure everything is kosher. But that's illegal.

If WhatsApp started transmitting E2E keys back to their servers people would find that out client side through network packet inspection, not server side.

Security researchers are limited in the tools/methods they can use. We have to work with what we've got at our disposal.

> Security researchers are limited in the tools/methods they can use. We have to work with what we've got at our disposal.

Which is exactly why "trust us, we're not going to do anything with these keys" is a ridiculous state of affairs and shouldn't be tolerated. We can't show that they're actually doing what they say, and it'll be years after they implement mass surveillance on the behest of law enforcement before someone leaks something.

Perfect security doesn't exist. If humans are involved at any point, it's not perfectly secure. The One time pad is a great testament to that.

Should we work towards an ideal? Sure. Should we stress out that things aren't perfect? Probably not.

It's an iteresting technical idea though. Would be interesting to see if any existing systems have a "canary" element to them.

There's a very simple solution to "the provider cannot prove that it will not misuse its access to the stream" - it's to use e2e encryption.

> I think I read that Zoom do decrypt AES-GCM server side already. They have to so they can put the little green box around the person currently speaking.

Why is this not a client thing?

Edit: Civility

* it used to be with ECB. not anymore. My bad.

> Matthew Green, a cryptographer and computer science professor at Johns Hopkins University, points out that group video conferencing is difficult to encrypt end to end. That’s because the service provider needs to detect who is talking to act like a switchboard, which allows it to only send a high-resolution videostream from the person who is talking at the moment, or who a user selects to the rest of the group, and to send low-resolution videostreams of other participants. This type of optimization is much easier if the service provider can see everything because it’s unencrypted.

https://theintercept.com/2020/03/31/zoom-meeting-encryption/

This was 2 months ago so their new white paper clarifies the current situation:

> For use cases such as meeting real-time content (video, voice, and content share), where data is transmitted over User Datagram Protocol (UDP), we use AES-256 GCM mode to encrypt these compressed data streams. Additionally, for video, voice, and content share encrypted with AES, once it’s encrypted, it remains encrypted as it passes through Zoom’s meeting servers until it reaches another Zoom Client or a Zoom Connector, which helps translate the data to another protocol.

https://zoom.us/docs/doc/Zoom%20Encryption%20Whitepaper.pdf

Ah, so their proprietary codec has come back to bite them in the ass.

(I realize codec is not the correct term.)