alt Hacker News> A cryptosystem is incoherent if its implementation is distributed by the same entity which it purports to secure against.
This is both true, and also useless: pretty much any E2E system is falling under this definition.
By definition you can't protect yourself from the entity that provides you the software you use, because you have now way to guarantee that they aren't going to backdoor you.
That doesn't mean it's snake oil though, as the entity you want protection against is generally not the software provider but a third party. Using e2e from a US-based entity means you are prone to spying from the US government, but at least you know you're reasonably secure against the IRGC, the Chinese intelligence service, the FSB, and so on.
It also means you are safe from data leaks, which are by far the most common threat today.
No system can be secure unconditionally, it's always secure under a particular threat model. And in practice “the attacker is able to deploy arbitrary code on your behalf for an extended period of time without being detected ” is a much narrower attack surface than “the attacker is able to obtain read-only access to your DB or your backups for at least a few minutes”. In the former case, the encryption being broken is also the least of your concern, as you've basically given remote access to all of your user's devices at this point…
Replies
> Using e2e from a US-based entity means you are prone to spying from the US government, but at least you know you're reasonably secure against the IRGC, the Chinese intelligence service, the FSB, and so on.
You don't need E2E for that, using https/TLS for transport and servers hosted in the US would be enough.
> By definition you can't protect yourself from the entity that provides you the software you use, because you have now way to guarantee that they aren't going to backdoor you.
But with repro builds and system transparency, hiding backdoors is impractical.
It's not useless, I don't think.
If the software is open source and you only install new versions after their source code has been audited, you should be ok.
> By definition you can't protect yourself from the entity that provides you the software you use, because you have now way to guarantee that they aren't going to backdoor you.
That's not completely true. If I can control when (and if!) the software updates and if there is some kind of vetting process to verify that the version I'm currently running does not contain a backdoor, I can treat it like a third party with respect to the server.
I agree with you though that most current software that are made to auto-update at any time without any oversight do not fall under this umbrella. Web apps definitely don't fall under it.
> the entity you want protection against is generally not the software provider but a third party.
This. The author is dismissing the whole web-based cryptography, or any end-to-end cryptography for that matter, on the basis of a one-dimension analysis.
a website can serve you a keylogger client and no one will ever know most likely, harder to do with binaries/sources
> This is both true, and also useless: pretty much any E2E system is falling under this definition.
This is not true. I can build Signal from source from GitHub, and use Signal-the-service with the client (which did not come from Signal, but GitHub/my compiler).
Many cryptosystems are like this. In any case, if you are getting something from the App Store, you can get it once and disable autoupdates, which prevents the service provider (presuming they are the same as the people who published the app) from backdooring you at some point in the future. Alternately, even with updates, unless Apple is colluding with them to serve only you* a specific backdoored app, you can at least be reasonably confident that it's not specifically backdooring only you* in an undetectable fashion.
>...pretty much any E2E system is falling under this definition.
The definition is quite clear. It does not apply when the implementation is not distributed by the same entity that creates it for example. There are other related issues but the message here is that web based cryptography has a particular weakness when it comes to things like end to end encrypted messaging which makes it so bad as to be worthless.
One thing you can do is have your adversary put their money where their mouth is and use the very same products, sourced independently, that they use to protect their own sensitive information.
There are limits to this of course. You can’t buy a TACLANE[1], but you can buy many of the other products[2] USG uses to protect its own classified information.
[1] https://gdmissionsystems.com/encryption/taclane-network-encr...
[2] https://www.nsa.gov/resources/Commercial-Solutions-for-Class...