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by whyoh 3442 days ago
>if WhatsApp actually did what you expect, data would be lost when a person switched phones in the middle of someone sending them a message

Only temporarily lost. WhatsApp could ask you: "do you want to resend the message(s) to the contact's new phone?". An easy solution and it could be optional, even off by default.
1 comments
FabHK 3442 days ago
I like that idea.

OpenWhisperSystem's response was that due to the delay involved the (potentially compromised) server would know who has enabled notifications/blocking and who hasn't.

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whyoh 3442 days ago
>the (potentially compromised) server would know who has enabled notifications/blocking and who hasn't.

How would that be worse than the current situation, where everyone is vulnerable and we all know it?

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FabHK 3442 days ago
From Moxie's response in another thread:

[...] a fact of life is that the majority of users will probably not verify keys. That is our reality. Given that reality, the most important thing is to design your product so that the server has no knowledge of who has verified keys or who has enabled a setting to see key change notifications. That way the server has no knowledge of who it can MITM without getting caught. I've been impressed with the level of care that WhatsApp has given to that requirement. I think we should all remain open to ideas about how we can improve this UX within the limits a mass market product has to operate within, but that's very different from labeling this a "backdoor."

https://news.ycombinator.com/item?id=13394900

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FabHK 3442 days ago
As a counterpoint, though, see the discoverer of the vulnerability:

"As Eike Kühl pretty well describes, this functionality only increases usability in a rare corner case: When you dump your phone in the ocean and you need a month to get a new one. Then everyone who has sent you a message during this period will not need to press an additional "OK" button."

https://tobi.rocks/2017/01/what-is-facebook-going-to-do-a-su...

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silentiumest 3442 days ago
This response is not valid as Tobias Boelter points out in his follow-up blog post: https://tobi.rocks/2017/01/there-is-a-whatsapp-backdoor/

>> Those "blocking" clients could instead retransmit a message of the same length that just contains garbage, i.e. instead of "Login with the password d98y289whcma0", they'd send "0000000000000000000000000000000000000" and this message would just not be displayed by the receiver's phone. By the guarantees of encryption, those two messages are indistinguishable in the encrypted form. Hence, this technique would make identifying users with the additional security enabled on a large scale impossible. <<

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