Technical FAQ on the Digital Markets Act

2022-03-30 — General — Matthew Hodgson

Hi all,

We've been flooded with questions about the DMA since it was announced last week, and have spotted some of the gatekeepers jumping to the wrong conclusions about what it might entail. Just in case you don't want to wade through yesterday's sprawling blog post, we've put together a quick FAQ to cover the most important points based on our understanding.

What does DMA mean for the gatekeepers?

The gatekeepers will have to open and document their existing APIs, so that alternative clients and/or bridges can connect to their service. The DMA requires that the APIs must expose the same level of privacy for remote users as for local users. So, if their service is end-to-end-encrypted (E2EE), the APIs must expose the same E2EE semantics (e.g. so that an alternative client connecting would have to implement E2EE too). For E2EE-capable APIs to work, the gatekeeper will likely have to model remote users as if they were local in their system. In the short term (one year horizon) this applies only to 1:1 chats and file transfers. In the long term (three year horizon) this applies to group chats and voip calls/conferences too.

Who counts as a “gatekeeper”?

The DMA defines any tech company worth over €75B or with over €7.5B of turnover as a gatekeeper, who must open their communication APIs. This means only the tech giants are in scope (e.g. as of today that includes Meta, Apple, Google, Microsoft, Salesforce/Slack - not Signal, Telegram, Discord, Twitter).

Does this mean the gatekeepers are being forced to implement an open standard such as Matrix or XMPP?

No. They can keep their existing implementations and APIs. For interoperability with other service providers, they will need to use a bridge (which could bridge via a common language such as Matrix or XMPP).

Are bridges secure?

If the service lacks end-to-end-encryption (Slack, Teams, Google Chat, non-secret chats on Facebook Messenger, Instagram, Google Messages etc) then the bridge does not reduce security or privacy, beyond the fact that bridged conversations by definition will be visible to the bridge and to the service you are interoperating with.

If the service has E2EE (WhatsApp, iMessage, secret chats on Messenger) then the bridge will necessarily have to decrypt (and reencrypt, where possible) the data when passing it to the other service. This means the conversation is no longer E2EE, and thus less secure (the bridge could be compromised and inspect or reroute their messages) - and so gatekeepers must warn the user that their conversation is leaving their platform and is no longer E2EE with something like this:


Why is the DMA good?

The upside is that the user has the freedom to use an infinite number of services (bots, virtual assistants, CRMs, translation services, etc) as well as speak to any other user in the world, regardless what platform they use.

It also puts much-needed pressure on the gatekeepers to innovate and differentiate rather than rely on their network effects to attract new users - creating a much more vibrant, open, competitive marketplace for users.

See "What's driven the DMA?" for more details.

If the DMA requires that remote users have the same security as local users, how can bridges work?

The DMA requires that the APIs expose the same level of security as for local users - ie E2EE must be exposed. If the users in a conversation choose to use a bridge and thus reencrypt the messages, then it is their choice to tradeoff encryption in favour of interoperability for a given conversation.

Does this undermine the gatekeepers’ current encryption?

Absolutely not. Users talking to other users within the same E2EE-capable gatekeeper will still be E2EE (assuming the gatekeeper doesn’t pull that rug from under its users) - and in fact it gives the gatekeepers an excellent way to advertise the selling point that E2EE is only guaranteed when you speak to other users on the same platform.

But why do we need bridges? If everyone spoke a common protocol, you wouldn’t ever have to decrypt messages to convert them between protocols.

Practically speaking, we don’t expect the gatekeepers to throw away their existing stacks (or implement multihead messengers that also speak open protocols). It’s true that if they natively spoke Matrix or XMPP then the reencryption problem would go away, but it’s more realistic to focus on opening the existing APIs than interpret the legislation as a mandate to speak Matrix. Perhaps in future players will adopt Matrix of their own volition.

Where do these bridges come from?

There is already a vibrant community of developers who build unofficial bridges to the gatekeepers - eg Element, Beeper and hundreds of open source developers in the Matrix and XMPP communities. Historically these bridges have been hampered by having to use unofficial and private APIs, making them a second class citizen - but with open documented APIs guaranteed by the DMA we eagerly anticipate an explosion of high quality transparent bridges which will be invisible to the end user.

Can you run E2EE bridges clientside to make them safer?

Maybe. For instance, current iMessage bridges work by running iMessage on a local iPhone or Mac and then reencrypting the messages there for interoperability. Given the messages are already exposed on the client anyway, this means that E2EE is not broken - and avoids decrypting them on a server. There is lots of development in this space currently, and with open APIs guaranteed by DMA the pace should speed up significantly.

How can you tell what service you should use to talk to a given remote user?

For 1:1 chats this is easy: you can simply ask the user which service they want to use to talk to a given user, if that user is not already on that service.

For group chats it is harder, and this is why the deadline for group chats is years away. The problem is that you need a way to verify the identity of arbitrary numbers of remote users on different platforms - effectively looking up their identity in a secure manner which stops services from maliciously spoofing identities.

One possible way to solve this would be for users to explicitly link their identity on one service with that on the gatekeeper’s service - eg “Alice on AliceChat is talking in the same room as Bob on BobChat; Bob will be asked to prove to AliceChat that he is the real Bob” - and so if AliceChat has already validated Bob’s identity, then this can be used to spot him popping up on other services. It also gives Bob a way to block themselves from ever being unwittingly bridged to AliceChat.

There are many other approaches too - and the onus is on the industry to figure out the best solution for decentralised identity in the next 3-4 years in order to realise the most exciting benefits of the DMA.


For a much deeper dive into the above, please check out our post at "How do you implement interoperability in a DMA world?"