Why the “WhatsApp-backdoor” is not a WhatsApp-backdoor

Post by mattcoles » Fri, Jan 13, 2017, 2:07 PM UTC

MyNameIsFred wrote: post #13

I do not see this as an actual rebuttal to the idea of it being a backdoor. The article makes two points: 1. Ultimately, verification falls to the user, so even in a secure system, user error, misunderstanding, and/or laziness can result in becoming compromised 2. Clients can lie to us anyway The point about this "backdoor" business is that the WhatsApp client does not even give the user the chance to even make a mis…

Post by rocqua » Fri, Jan 13, 2017, 2:10 PM UTC

taneq wrote: post #14

jMyles wrote: post #8

It is sad, and misinformative, that this article is currently #1 on HN, while the much more accurate and better-written Guardian piece "WhatsApp backdoor allows snooping on encrypted messages" is #2. The linked piece is hard to critique because it's borderline incoherent. The "conclusion" is simply not a conclusion, particularly this passage: > A provider always has the ability to intercept messages as long as the us…

Apart from the horrifying punctuation, I can't see how the quoted paragraph is technically incorrect. Some kind of real-world validation is required before you can trust that a public key really represents a given entity (at least, that's how I'm interpreting "verify fingerprints") and so it follows that if users don't validate the public keys of their correspondents, they can't know for sure that their conversations…

Post by rocqua » Fri, Jan 13, 2017, 2:20 PM UTC

Eyas wrote: post #9

venomsnake wrote: post #2

No it is a backdoor. Becuase the app fucks you on purpose, even if you go to great lenghts to verify the keys. Also the vulnerabilty matches perfectly one scenario - when a person is in custody, the LEO cannot open its phone, but they can create account on new device with his sim card and continue "trusted" chats.

I understand why that is a concern for the security conscious. But for the 90% use case, e.g.: I lost my phone and got a new one. Or my phone isn't turning on and I get a new one. I install WhatsApp. How do I roll over my identity? The way I see it is that WhatsApp is delegating the task of identity verification to the network provider (admittedly a weak link for the security conscious). But it _is_ the easiest way f…

Post by slashcrypto » Fri, Jan 13, 2017, 2:26 PM UTC

rocqua wrote: post #23

taneq wrote: post #14

Earlier quoted context omitted.

Apart from the horrifying punctuation, I can't see how the quoted paragraph is technically incorrect. Some kind of real-world validation is required before you can trust that a public key really represents a given entity (at least, that's how I'm interpreting "verify fingerprints") and so it follows that if users don't validate the public keys of their correspondents, they can't know for sure that their conversations…

The paragraph is correct but misses the point. Whatsapp will re-transmit messages with a key provided by whatsapp without ever giving the user the option to verify that key. Even with the opt-in, the message will be re-transmitted. All the opt-in ensures is that you are notified of the key change (a notification you receive after the message has already been re-transmitted under the new key)

Post by sfifs » Sat, Jan 14, 2017, 6:35 AM UTC

jMyles wrote: post #20

sfifs wrote: post #18

Earlier quoted context omitted.

It's actually very accurate technically. The Guardian article seems to miss the basic point. The encryption in WhatsApp and Signal and Apple messaging all are all built to protect data from others in transit not necessarily from the service provider itself. No system where a central service provider manages both key infrastructure and message delivery can ever be secure from MITM by the service provider unless you do…

But the actual point here is the retransmission vulnerability. That's what makes WhatsApp different. That's the backdoor.