WhatsApp is still closed-source though, and I'm unsure as to the veracity of the claim of end-to-end encryption, I sure hope that's the case. In the Panorama documentary about Edward Snowden on the BBC, when discussing the death of Lee Rigby, a representative of Facebook says they're capable of decrypting messages (whether that applies to WhatsApp or just Facebook messenger is not clarified.)

https://www.youtube.com/watch?v=SjVxqlncS2I&t=46m15s (also see 49:00+)

You might be interested in this set of videos[1] of public testimony by WhatsApp's Deputy General Counsel at a hearing on cybercrime in Brazil in December 2015, where he explains in some detail the type of information they have and don't have. He explicitly notes that they are incapable of accessing message content for end-to-end encrypted messages, and also explains that they don't retain copies of any communications once they've been delivered to recipients.

[1] http://www2.camara.leg.br/atividade-legislativa/comissoes/co...

I think that only messages sent between two android devices are encrypted using E2E. If you send a message to your mom (who uses a blackberry), the message won't be encrypted with that protocol.

What about ios? And how does your device know whether to encrypt or not? It's useless talking about encryption if the code is hidden. What if tomorrow they turn off the encryption silently?

They can turn off the encryption silently whether or not the code is hidden.

How so? You can compile yourself if you like.

More importantly, you could change the client to show encryption status before a message is sent and add client-side key management.

Sorry, I meant for the pre-compiled versions on Google Play and the App Store. The vast, vast majority of Whatsapp users aren't going to want to or don't know how to compile the app for their phone.

It's easier to say "no" to Brazil.

If they're partnered with Open Whisper Systems, it sounds like they're serious about end-to-end encryption.

They still keep a copy of all client encryption keys. :\

They have to. A phone number is not a key, so there's no way to avoid that.

However I've seen leaked screenshots that suggest at least the Android client is getting the ability to see what the keys are and pin them. Hence, TOFU encryption. It's about the best you can do in a consumer product.

Last time I checked whats app didn't require any kind of OOB key exchange, or ability to set your own password. So any claims about having end to end encryption are misleading.

> Last time I checked whats app didn't require any kind of OOB key exchange, or ability to set your own password.

Neither does Signal/TextSecure. Signal most definitely has E2E encryption.

However, when your primary device is wiped (or changed)[0] your Signal crypto keys are changed and your conversation partners are alerted to this fact.

Do you know what happens when the same thing happens to a WhatsApp user? (I don't. :( )

[0] Or -yanno- one just clears all Signal app data

If someone generates the keys, same someone can decrypt. You cannot establish secure connection without someone's trusted server. By that definition same server could MITM you.

> If someone generates the keys, same someone can decrypt. You cannot establish secure connection without someone's trusted server. By that definition same server could MITM you.

Every word in your first and third sentences are true. As written, your second sentence is iffy at best. [0][1]

However, the situation that those sentences describes does not apply to end-to-end encryption in Signal. Signal's crypto keys are generated on the end-user's device and never leave that device.

Signal neither requires OOB key exchange, nor does it require that you set a password to encrypt Signal data while on disk.

Because Signal has the same properties that you claim are indicators of a lack of E2E encryption, but actually is E2E encrypted, it's clear that these properties are not proof positive of a lack of E2E encryption.

So, I reword my previous question, which you failed to address:

What happens when a WhatsApp user gets a new phone, wipes his existing phone, or simply clears all locally stored WhatsApp app data? Does he get a new set of crypto keys, and are his conversation partners alerted of this fact as happens in Signal?

I ask because I don't use WhatsApp and don't know the answer to the question.

[0] Consider Diffie-Hellman key exchange. This is a method whereby two parties who wish to communicate securely over a hostile channel can do so without divulging any key material to eavesdroppers listening in on the exchange.

[1] To address the possibility that you're talking about key verification, rather than secure peer-to-peer session creation: if you like, Signal will show you the fingerprint of your encryption key. You can use that fingerprint to perform any OOB key verification that you want.

You contradict with your previous statement that Signal does not provide OOB key verification when they show you the fingerprints. Because that is essential for not being MITM.

> You contradict with your previous statement that Signal does not provide OOB key verification...

I do no such thing because I never made such a statement. I addressed your claim about mandatory OOB key exchange, not optional verification. To jog your memory, the two times I brought up OOB exchange were as follows:

>> Last time I checked whats app didn't require any kind of OOB key exchange, or ability to set your own password.

> Neither does Signal/TextSecure. Signal most definitely has E2E encryption. [0]

and

> Signal neither requires OOB key exchange, nor does it require that you set a password to encrypt Signal data while on disk. [1]

Notice that I talk about how Signal doesn't require OOB key exchange, not that Signal doesn't provide OOB key verification.

[0] https://news.ycombinator.com/item?id=11124807

[1] https://news.ycombinator.com/item?id=11125534