Comment by johnecheck
9 hours ago
I find this unconvincing. Isn't this the exact same security posture as a native app with automatic updates turned on?
If your thought is just "disable automatic updates", there's no reason you couldn't do the same by declining new versions of a web app. Unless you built it yourself (as a web app or native app), you need to include the servers and DNS in your trust model.
To me, it seems entirely isomorphic. The only material difference I see is whether automatic updates are on by default (an OS/browser vendor issue, not anything inherent to the tech).
> Isn't this the exact same security posture as a native app with automatic updates turned on?
It's not, I don't think so. For instance, if you install Signal on your Android, the apk was signed by Signal, sent to Google and distributed by Google. Google cannot modify it, because Signal has to sign it. So in order to make you install a "malevolent" version of Signal, Google has to collude with Signal.
Of course you can download and install the apk from Signal's website, in which case Signal may give you personally a malevolent version. But you can easily compare that file to someone else's. On Android there are verifier apps that allow you to check that.
Finally if E2EE does matter a lot to you, you can compile Signal yourself from the sources, and even go as far as auditing those sources yourself.
You don't get to do any of that on the web. When you load ProtonMail in your browser, you don't have any practical way to verify that the code your browser is running is the same as everybody else who is running it around that time. You have to trust Proton that they give you code that prevents them from reading your emails. It is better than nothing or course, but it still means that you have to trust Proton.
This can be solved by a nobus backdoor.
> if you install Signal on your Android, the apk was signed by Signal, sent to Google and distributed by Google. Google cannot modify it, because Signal has to sign
I'd stress that for specifically Signal this seems to indeed still be true, but almost apps on Google Play are now signed by Google (with keys either generated by them or provided to them), and even customized by Google for your specific system.
Google requires it for all apps created after August 2021. *
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> On Android there are verifier apps that allow you to check that.
If you mean Accrescent, it only checks the app's signature, not the hash of the individual versions.
I only know APK redistributors such as apkmirror that might let you check the individual app version, but they don't have API access and only host some apps.
And again, now almost apps on Google Play are signed by Google and customized on the fly for your device, so you typically can't really confront them.
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* Except that apparently, since a couple months ago Google allows you to use their HSMs?
Even this magnanimous concession though is “strictly for enterprise organizations with mandatory compliance, regulatory, or policy requirements to retain key custody in an external Google Cloud KMS instance” (https://developers.google.com/android-publisher/api-ref/rest...).
There's some chance that they can't access these keys; but the app needs to be compiled on their servers, so yeah, plenty of ways for them to meddle with it, and probably even to issue signing requests.
This seems to have been introduced in July, it's the first time I hear of it
> but almost apps on Google Play are now signed by Google (with keys either generated by them or provided to them),
Yes! Google's goddamn "bundles" seem to be enforced to everybody. I guess part of Google "not being evil" and all. Another reason why initiatives like EU's Digital Markets Act are needed, I guess.
And yet another reason to use GrapheneOS, of course.
> If you mean Accrescent, it only checks the app's signature, not the hash of the individual versions.
No, there is an app called "AppVerifier" actually. That's the one I meant.
1 reply →
Automatic updates should be read as "automatic backdoors".
> I find this unconvincing. Isn't this the exact same security posture as a native app with automatic updates turned on?
Mostly. But the alternative shouldn't be a native app that updates itself, but rather a native app that is updated by a package manager. The big difference is traceability and auditability: With a trusted package manager (and even in good app stores) the company can only decide to push an update to everyone or to no-one. There is no way to push an update just to the pesky journalist or whistle blower. A covert attack is really hard to accomplish this way.
Exactly, to me there are two requirements:
* The cryptography must be sound. That's the obvious one, if it's not encrypted then it's not "end-to-end" encrypted.
* There must be a practical way for the user to "verify" (with some definition of verifying) the client they are running.
A web browser doesn't provide that at all. It does not mean that everything else provides it: there are many ways to provide a Desktop app that break E2EE, but that is a different discussion. My point is that fundamentally, the web browser does not provide that. It's not that the laws of physics prevent it, it's just that the web browser never chose to provide that.
> it's just that the web browser never chose to provide that.
Yes, this exactly. If we wanted ‘verifiable’ app distribution via browser, then we’d need browsers to implement some way to cross check the code downloaded vs a publicly published list somewhere - similar to certificate transparency or what WhatsApp is trying to do with an extension [1]. Without that, web apps are left working with a weaker threat model.
[1] https://engineering.fb.com/2022/03/10/security/code-verify
6 replies →
> Isn't this the exact same security posture as a native app with automatic updates turned on?
Inconvenient truth, but it is so to a degree. I am disturbed by the lack of attention to that by many security gurus.
One difference is that with web apps you're practically updating them every single time you launch them.
It depends on how the automatic updates are handled.
App updates can be cryptographically signed with a key that’s kept offline and only held by a few people. Your trust in the app can be equal to your trust in those people, multiplied by your trust in the technology that keeps those offline keys safe from compromise.
Your trust in a web app will be equal to your trust in the people running the server multiplied by your trust that the server isn’t compromised. Since the server is necessarily always online, that trust will be much lower.