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by celoyd 5861 days ago
(Friend of the OP here.)

That’s true, but it’s a problem with pretty much everything. Google (or an impostor) could, once in a million requests, send you JS that posts your Gmail password to Twitter. You probably don’t trust this site as much as Google, but the JS is unobfuscated and you can dump your traffic. That’s about as much as anyone can offer.

Personally verifying the code and hashing it every time you use it (or whatever) is a big headache. But if you’re that serious about security, it applies to everything. Bonchat adds the unusual feature that, once you’ve done so, you know that the server can’t even theoretically read your chat. (Assuming AES is unbroken.) This is a step above Gmail etc.
1 comments
tptacek 5861 days ago
Yes. You are right. It is the problem with pretty much everything. The issue here is that you haven't solved that problem. So your application is no more secure than anything.
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celoyd 5861 days ago
No. Assuming it’s correctly implemented, it’s more secure than an identical app that sends the password over SSL to the server.

This is not an innovation in cryptographic theory, but it’s something you don’t usually see in a web app.

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tptacek 5861 days ago
It's something you don't see in web apps because the idea has been roundly rejected. Because in almost every setting where you could possibly implement crypto in JS, you have to run the app over HTTPS anyways, you gain only epsilon more security than if you would without added crypto --- and that's if you get everything right.
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celoyd 5861 days ago
Sure. As this is designed now, HTTPS’s prevention of malicious JS insertion is the big weak point I see. But it’s implicitly asking what you could do if you found ways of getting around that, for example by using client-side caches of the code after a strict initial check.

The real wow for me here is that JS is fast enough to do AES-128 at comfortable chat speed. That’s really suggestive. It’s an epsilon, but it’s a fertile and interesting epsilon.

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tptacek 5861 days ago
Nothing you just said is in the marketing material for this. Instead, it promises to be (paraphrased generously) so secure that not even the operators can tell what people are saying over the service.
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