The integration of encryption end to end of WhatsApp was great news for users, who finally could be confident about the privacy and security that gave this instant messaging service.
Everything seemed to be perfect until a few hours ago The Guardian publish a story in which he warned of a WhatsApp security hole that could allow an attacker to intercept encrypted messages and view its contents. That security hole does not exist , and what happens is that some media have not understood how key encryption system work. WhatsApp encryption works just the way you should.
What was the alleged problem?
In The Guardian they explained how WhatsApp could force a mobile customer service to generate new encryption keys, which would enable those responsible for the service could intercept the key exchange and, therefore, intercept subsequent messages.
As explained by a security expert in his blog, " this is the way in which a man-in-the-middle attack works, and only works when both parties which communicate with the other not verify the fingerprint of those exchanged keys ".
Both Signal and WhatsApp make use of a system called TOFU ( "Trust Of First Use", "Trust in the first use"), and according to that principle when a key is exchanged, that is the key that is trusted for communication As long as the key does not change.
Although Signal works in a different way if that key changes (blocks outgoing messages and sends new until manually check the new keys), the way of working of WhatsApp is equally valid , although this expderto notes that WhatsApp is still proprietary code And that does not really "audit" how the company works when this happens. Other experts also explained the functioning of WhatsApp in the past and the superiority of Signal in this area.
It is not a fault, but a characteristic
Security experts responded to the Guardian article with harsh criticism at what was simply a misconception . The use of the Signal encryption protocol developed by the company Open Whisper Systems works through some encryption keys that must be verified.
Frederic Jacobs, head of iOS development for that company, commented how the only thing that happens is that you have to verify the keys, otherwise a man-in-the-middle attack may occur: someone could be in the middle of the communication And intercept those messages. The problem is that this is not a security hole, but a feature of the encryption system : until the keys are not verified its authenticity is not guaranteed.
In fact, another expert named Alex Muffet revealed after talking with Gizmodo that this " is not a bug, it works as it was designed to do and someone is saying it is a" hole "and pretending that it is a chaos when the fact is that you can totally ignore . " According to Muffet:
There is a feature in WhatsApp that - when you switch phones, buy a new one, do a factory reset, whatever - when you install WhatsApp for the first time on the new phone and continue a conversation, the encryption keys are renegotiated to fit the new phone.
In fact taking advantage of this to try to intercept a conversation would be very complex. Firstly they would have to be messages that are stored waiting to be received by the other person (if for example has the mobile off). In this case someone who would work on Facebook or WhatsApp would have to simulate that the receiver has a new phone to return messages are encrypted and will be sent to a new fake phone.
In short: the problem of accusing WhatsApp is a well known systems exploit encrypted messages (EFF discussed the issue in October last year), but also that exploit is very difficult to exploit. So, do not worry: no security hole, and your messages are safe.