[messaging] WhatsApp & OWS team up

[Thijs Alkemade]

> On 19 nov. 2014, at 11:40, Mike Hearn <mike at plan99.net> wrote:
> 
> Note that given everything was SSL protected before, and WhatsApp I believe does not log messages so could not provide past messages anyway (except perhaps if they were buffering up waiting to be delivered?) and keys can be changed at any time or forward security disabled entirely for certain user populations without them knowing .... then using the TextSecure protocol inside SSL doesn't actually change much immediately. I see it more as a useful next step, that can be built upon to achieve more impactful change in future.

WhatsApp doesn’t use SSL for the messages, at least did not last year. They used a hand-rolled protocol based on RC4, making elementary mistakes such as using the same keystream for the client->server and server->client data.

Whether the protocol classifies as forward secret is debatable. After connecting, the server sends a message “use this key for the next login”, so it does use ephemeral keys, but compromising one key does reveal every future session (as long as all have been captured).

Regards,
Thijs
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