I've seen a lot of discussions in the last week about the Web Environment Integrity proposal. Quite predictably from the moment it got called things like "DRM for the web", people have been arguing passionately against it on HN, Github issues, etc. The basic claims seem to be that it's going to turn the web into a walled garden, kill ad blockers, kill all small browsers, kill all small operating systems, kill accessibility tools like screen readers, etc.

The Web Environment Integrity proposal is basically:

  • A website can request an attestation from the browser
  • The browser forwards the attestation requests to an attester
  • The attester checks properties like hardware and software integrity
  • If they check out, the attester creates a token and signs it with its private key.
  • The attester hands off the signed token to the browser, which in turn sends it to the website.
  • The website checks that the token was signed by a trusted attester

Here's a funny thing I suspect few of those commenters know: A very similar mechanism already exists on the web, and is already deployed in production browsers (Safari), operating systems (iOS, OS X), and hosting infrastructure (Cloudflare, Fastly). That mechanism is Private Access Tokens / Privacy Pass.

Here's what PATs (as deployed by Apple, and on by default) do to the best of my understanding:

  • A website can request an attestation from the browser
  • The browser forwards the attestation requests to an attester
  • The attester checks properties like hardware and software integrity.
  • If they check out, the attester calls the website's trusted token issuer
  • The issuer checks whether to trust the attester and whether the information passed by the attester is sufficient, and then issues a token signed by its private key
  • The attester hands off the signed token to the browser, which passes it to the website.
  • The website checks that the token was signed by a trusted token issuer

This launching was hailed in the tech press as a win for privacy and security, not as an attempt to kill accessibility tools or build a walled garden. [1]

You might notice that the basic operating model of the two protocols is almost exactly the same. So is their intended use. From the "DRM for websites" perspective, I don't think there is a difference.

With both WEI and PATs, the website would be able to ask Apple to verify that the request is coming from a genuine non-jailbroken iPhone running Safari, and block the ones running Firefox on Linux. And in both, the intent is not for the API to be used for that kind of outright blocking.

Neither lists e.g. checking whether the browser is running an ad blocker extension as a use case. Both would have just the same technical capabilities for making that kind of thing happen, by just having the attester check for it, and I bet that in both cases the attester would be equally unmotivated in actually providing that kind of attestation.

It's also not that PATs would somehow make it easier for people to spin up new attesters for small or new platforms. Want to run your own attester for PATs? You could, but the issuers you care about will not trust it. [2]

Now, the technologies aren't quite identical, but the distinctions are subtle and would just matter for exactly the kind of anti-abuse work that both of the proposals were ostensibly meant for. The big one is the WEI proposal including the ability to content-bind the attestation to a specific operation. It's a feature anyone trying to use a feature like this for abuse prevention would think is needed, but that adds no power to the theorized "DRM for the web" use case. There is also a more obvious difference between the two, with whether the attester and issuer are the same entity or split seems. But that too is irrelevant in the discussion on how the technology could be misused. [3]

In principle there could also be differences in the exact things that the APIs allow attesting for. But neither standard really defines the exact set of attestations, just the mechanisms.

Given the DRM narrative would have worked exactly the same for the two projects, why such a different reception? I can only think of two differences, both social rather than technical.

One is that the PAT (and related Privacy Pass) draft standards were written in the IETF and are dense standardese. There was no plaintext explainer. Effectively nobody outside of the internet standardization circles read those drafts, and if they had they wouldn't have known whether they needed to be outraged or not. The first time it actually broke through to the public was when Apple implemented it.

The other is the framing. PATs were sold to the public exclusively as a way of seeing fewer captchas. Who wouldn't want fewer captchas? WEI was pitched as a bunch of fairly abstract use cases and mostly from the perspective of the service provider, not for how it'd improve the user experience by reducing the need for invasive challenges and data collection.

This isn't the first time I've seen two attempts at a really similar project, with one getting lauded while the other gets trashed for something that's common to both. But it is the one where the two things are the most similar, and it feels like it should be instructive somehow.

If the takeaway is that standards proposals should be opaque and kept away from the public for as long as possible, before being launched straight to prod based on a draft spec, that'd be bad. If it's that standard proposals should be carefully written to highlight the benefit for the end user, even starting from the first draft, that's probably pretty good? And if it's that only Apple can launch any browser features without a massive backlash, it seems pretty damn bad.

[1] Just to be clear, the one significant HN discussion on PATs had similar arguments about it being DRM, so my claim is not that absolutely everyone loved PATs. But it didn't actually get traction as a hacker cause celebre, and as far as I can see the general media coverage was broadly positive.

[2] What's the process for getting Cloudflare or Fastly to trust a non-Apple attester anyway? I can't find any documentation.

[3] The split version seems kind of superior for deployment, since it means each site needs to only care about a single key (their chosen issuer). This makes e.g. the creation of a new attester a lot more tractable. You only need to convince half a dozen issuers to trust your new attester and ingest the keys, not try to sign up every single website in the world one by one.