Tobias Boelter

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. <<

The dispute is really Facebook vs Tobias Boelter (https://tobi.rocks/), with Manisha Ganguly (freelance, so not really The Guardian) putting pressure on Facebook. I think it's more that the media is biased against corporations, because positive information about corporations sounds like an advertisement or is instead attributed to the employee. Headlines like "Zuckerberg fires 100 employees" or "Wal-mart saves puppy" seem to be either rare or nonexistent.

Stop believing the marketing, they can say message is end to end encrypted even if they encrypt it twice, once with apple key and once with "end" key (actually it is more complicated, but for the sake of this debate it is good enough, for a simple algorithm, check bellow) Before you start downvoting spree, read this: For Apple: https://mashable.com/2013/10/17/apple-nsa-imessage http://bgr.com/2015/08/06/iphone-fbi-imessage-facetime-backdoor/ https://www.tripwire.com/state-of-security/latest-security-news/apple-… For WhatsApp: https://tobi.rocks/ (encrypt data with random key with symmetric encryption algorythm (AES,...), which is then encrypted and stored with the mesage twice. Once encrypted with recipient public key (asymmetric: RSA,ECC) and once encrypted with apple public key. This way you can say that you are having end to end encryption while you can still read everything and you can also use all the nice words in marketing material, AES, end2end, RSA/ECC,...).

I am flagging this article, as the headline and first few paragraphs are very misleading, based on my understanding from: https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/ They make it sound like an intentional backdoor has been introduced to WhatsApp to facilitate monitoring. Rather, it seems like there's a weakness in the implementation, where if a message is undelivered, an attacker could trick the sender's client into sending the undelivered message to a new key they control. That does seem like a weakness, but not an intentional backdoor as the article initially lead me to believe. I could see how someone would trade off ease of use and message delivery with security and make that call. Yes, it could be a subtle backdoor (with limited exploitation), and yes, open source clients would be great. But real end users use WhatsApp to encrypt their private messages on a scale never before achieved, because of the usability tradeoffs they've made. I think we should bear that in mind before describing any implementation tradeoff as a 'backdoor'.

Switching SIMs means switching accounts, because phone numbers are usernames, right? Why would the application hide this by default? Also, why would the key change be hidden by default when the phone number doesn't change? This is the actual mechanism described by Tobias Boelter in his report: https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/ Is this done to facilitate the "same SIM, lost local storage" scenario? Then the phone number is not only username but also a password and anybody able to steal the phone (or just the number) can impersonate a WhatsApp user. Is this the level of security these experts are protecting?

response: https://tobi.rocks/2017/01/there-is-a-whatsapp-backdoor/

The discoverer of the vulnerability, t0b0, is weighing in again, saying there is a backdoor: https://tobi.rocks/2017/01/there-is-a-whatsapp-backdoor/ Edit to add: It's also on HN (empty so far): https://news.ycombinator.com/item?id=13404263

For those not wanting to watch 14 minutes of video, here is the author's blog post explaining the vulnerability: https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/

Adding to this reply, here is the actual complaint that generated the guardian's article: https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/

More details in "WhatsApp Retransmission Vulnerability" [1] from April last year. [1] https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/

I'm trying to understand this same thing. I don't see why triggering a client to generate new keys is a problem. Giving the client keys to use is a problem, but that's not what it's saying. Edit: it is described much better here: https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/ The idea is that in addition to the keys being regenerated, the recipient phone is spoofed (a key point not mentioned). So the FBI could tell the Whatsapp company to generate a fake recipient phone and connect the sender phone to that phone instead.

Some more background: This was presented in the lightning talks at 33c3, starting around minute 48: https://media.ccc.de/v/33c3-8089-lightning_talks_day_4 Here's the congress wiki with some more links: https://events.ccc.de/congress/2016/wiki/Lightning:A_Backdoor_(/Bug%3F… And a blogpost: https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/

because here it clearly says that signal had dealt with this problem https://tobi.rocks/2016/04/whats-app-retransmission-vulnerability/ So it is solely whatsapp's fault