Zoom Rolling Out End-to-End Encryption Offering

In both the "normal" case and in situations where end-to-end encryption is enabled, the audio and visual streams are individually encrypted with AES-GCM-256 using a key derived from a shared per-meeting key. The difference is that in the normal case, the per-meeting key is stable for the entire meeting and is available to Zoom (as is needed for POTS bridge, cloud recordings, etc...). When the meeting is E2EE, the key is generated by the host, distributed to the other attendees, and rotated as the meeting participants change.

Details: https://github.com/zoom/zoom-e2e-whitepaper/blob/master/zoom...

Zoom's development team is based in China [1]. Could the government there force these devs to "enhance" this encryption with a backdoor or two for "state security" reasons?

[1] https://www.forbes.com/sites/thomasbrewster/2020/04/03/warni...

What was published not too long ago: https://github.com/zoom/zoom-e2e-whitepaper

AES-GCM has serious problems with nonce reuse when you have encrypted a lot of data. As I recall, solving that problem was part of the CESAR competition a couple years back.

I'm also very curious about this. AES-GCM satisfies my threat model, "enhanced" does not.

I clearly read it as enhanced compared to the previous versions, which used to be AES-ECB until earlier this year.

Note how it mentions "How is this different from Zoom’s enhanced GCM encryption?", which means enhanced also applies to the normal Zoom meetings which are encrypted but not E2E, and supports this interpretation.

Yeah symmetric ciphers are easy (TM), it's the pub key shit that really gets you.

Perhaps enhanced means backdoor-ed.

The point of end-to-end encryption is to prevent a government from being able to access your communications afterwards. Zoom or any other private company is much more able to implement a standard technical solution like end-to-end encryption than to resist legal subpoenas for information they have but would prefer to not have.

They are not opening their source code, as far as I know, so who is auditing this supposed end-to-end encryption?

I agree. But I suppose it does have a slight benefit that if you trust the individuals at Zoom who implemented the encryption, now you no longer need to also trust the individuals at Zoom who have access to network traffic and/or server-side code but not client application code.

This slight benefit is fairly silly, because we have no reason to give greater credibility (regarding ethics) to one set over another. At least it's a smaller set, though.

Well they previously claimed their service was E2E, then there was a furore when it was discovered that was not true, after which they claimed their service was E2E, when it still was not.

Considering their growth throughout, why would they waste their time implementing it fully and correctly?

With a closed-source client, how do we know Zoom does not add itself as a un-anounced participant in a meeting??

I assume there will be analysis done in the near future by third parties, but even that analysis is not sufficient to protect against a future change or a one-off, court-mandated targeted "switch" to join a un-announced participant to a meeting. The client can be designed to be 'dumb' in this regard.

They acquired the Keybase team to implement this. If there is a backdoor, I'd expect a mass exodus of the team.

Honestly, I know they hired a good team to do it and stand to lose everything if they didn't implement it properly... but they lied about it once and that was so brazen that I won't believe it until it's confirmed by at least a few independent experts. Zoom, in my mind, is synonymous with invaded privacy, poor security and lies.

It appears to tick all the boxes other than verifiable client binaries...

So ahead of things like iMessage. About the same as stuff like Whatsapp. Behind things like Signal, Telegram, PGP and the like.

Noob question here: is it difficult to implement E2E encryption one would think Zoom has all the resources required to build such a system?

> Who of the readers here believe this is a true E2E encryption - so that even government can not see the content?

Pfahahahahahaha.

More seriously, my understanding is that Zoom uses automatic updates, so it can never be secure even in the unlikely event the code that's on your machine this week actually does correctly implement end-to-end encryption. Also, if you're trusting Zoom's servers to give you the encryption keys you have a MitM attack waiting to happen.

I think it won't be designed with a built-in backdoor, but probably also not designed very well. Like WhatsApp instead of Signal. Closed source, edge cases not covered well, etc. Not going to be anyone's go to for high-assurance protection from state actors.

It's kind of a moot point since the government already has backdoors built into operating systems, hardware chips, browsers (therefore can enable screen-sharing + other hardware settings remotely), etc.

"True" E2E encryption doesn't really exist nowadays, at least in the context of being spied on by governments.

Edit: Direct sources don't really exist for obvious reasons. Google it, and there's plenty of articles to help you read between the lines. If you think the govt isn't capable or interested in this, you're being naive.

IIRC they even were marketing their usage of SSL as e2ee in their website for some time.

>You can never trust that your connection is end to end encrypted unless you run encryption yourself

I also can't trust that the meat I buy in the supermarket actually has in it what it says on the packaging technically speaking unless I slaughter a pig myself. Obviously this isn't a reasonable standard to treat anything by.

When a company goes out of their way to actually sell you E2E encryption and the company actually is fairly known and thus liable I can at the very least assume, for practical purposes that they're not lying to me until proven otherwise because they're risking their entire reputation and probably a very costly legal battle.

Do-it-yourself encryption isn't really realistic because it's not going to be used by ~99% of people.

I have never "run encryption myself" when connecting to my bank's web site. Have you?

I think for us techy people, we image a future where people interact with each other virtually. Today in video calls, tomorrow will be in ever realistic virtual reality. Maybe at some point we will be so good at mimicking reality and also so good at creating new scenarios where it is not possible in reality. But after this experiencing this pandemic, staying home for more than half of the year, interacting people remotely, at least for me, I can't wait for the time to finally able to meet people face to face. Even though a lot of companies have offered forever working from home, I don't think I will take that offer. Its just feels so much better to talk to people, see people in person. Whether its the body language, people's emotions, or physical interactions, and the in the moment and immediateness of everything. I don't think computers, VR and AR will ever going to replace that experience.

For zoom though, I think that they will continue to find ways to extract more revenue per users. I think what will increase in the future is more and more economy will be digital economy, and people will be more willing to pay for and do commerce in a virtual platform. And companies will find ever more commerce opportunities with digital technologies. So I think they will continue to increase their revenue.

Zoom has quarterly revenue of $600 million, not annual.

I'm not sure it's still really cognitive dissonance when they admitted their error in marketing it that way, announced they were working on exactly this to provide what their claims said, and now they're saying it's done?

Sounds like they got a sudden spike in interest, realized that their customers were angry, admitted the error, bought keybase, and provided what their customers asked them for.

Zoom is guilty of alot of stupid stuff, but the "E2E" controversy is the among the dumber controversies. Zoom's characterization of end to end was referring to the transport layer between the clients and Zoom service endpoint. The more serious issue there was that until a point in the recent past, they weren't using an appropriate cipher mode.

E2E in the sense that security nerds bang their chests about isn't what customers want. Boards of directors of public companies, some attorneys, and some others need it. Almost nobody else does. It means that you don't have cloud recording, can't use POTS phones to connect to the meetings, etc. People with those needs have security controls beyond the software, so they probably need something like Webex, or should be using directly connected room systems. Someone who needs E2E for real reasons aren't doing it from home, for example, as you need to take other measures to protect that meeting content.

IMHO, the acquisition was mainly for two reasons: - signaling, to its customers and the market that they are taking this issue seriously - management "cover-my-ass": if somehow the overhaul is taking longer than expected, someone can claim "we tried everything we could"

There are secondary benefits, the acquisition did bring some probably-helpful talent around encryption/infosec, but as you said the rollout seems really fast vs acquisition time for a product that size.

Probably, the blog post itself is signed by Max Krohn, Keybase.io co-founder.