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They're using the NaCl library for cryptography and proper encryption of messages before leaving the phone can be validated here: http://threema.ch/validation/
(I'm not affiliated with Threema, just a regular user who likes the product)
That second bullet point set off my BS detector (and is where I stopped reading). No system on earth lets you reliably delete a message sent to another device over the Internet, after the fact. Neither can any such system reliably prevent users from sharing pictures that they can see on their device.
This site reads like an add for a perpetual motion engine.
Which is too bad, because open-source encrypted mobile chat is an interesting thing in and of itself, without impossible pie-in-the-sky claims.
"Only the person you send the message to can read it. Period." To use this kind of sentences on new software not reviewed by the comunity is dangerous. There is people that risk their lifes using this kind of app. The thing that puzzles me is that sentence: "You can delete your message from the receivers phone." I don't see in the 'how it works' any information about it. Do they do that in a cryptographic way somehow…
It is also false, since it seems that their threat model also includes the server being able to transparently MITM you and read all your messages. A pretty egregious overstatement, I think.
You can delete your message from the receivers phone. That second bullet point set off my BS detector (and is where I stopped reading). No system on earth lets you reliably delete a message sent to another device over the Internet, after the fact. Neither can any such system reliably prevent users from sharing pictures that they can see on their device. This site reads like an add for a perpetual motion engine. Which…
Also check out https://threema.ch/en/ - it has the same functionality as WhatsApp (except of group chat), but secure/encrypted and is available for Android and iOS. They're using the NaCl library for cryptography and proper encryption of messages before leaving the phone can be validated here: http://threema.ch/validation/ (I'm not affiliated with Threema, just a regular user who likes the product)
* No details of threat model
* No details of crypto protocols used
* No discussion of how key exchange problem is solved
* Makes misleading security claims "when you delete a sent message it will be removed from the receivers phone"
Basically falls into "don't touch with a barge pole" category of crypto software.
Crypto software isn't a category where you can make it up as you go along, it has to be designed upfront with a set of security considerations for it to have a chance of survival in the real world.
You can delete your message from the receivers phone. That second bullet point set off my BS detector (and is where I stopped reading). No system on earth lets you reliably delete a message sent to another device over the Internet, after the fact. Neither can any such system reliably prevent users from sharing pictures that they can see on their device. This site reads like an add for a perpetual motion engine. Which…
Well, they didn't say "reliably". Many apps do this on a best-effort basis, it's usually good enough but people shouldn't trust it too much.
> Be confident sending private information and pictures.
... be confident? That kinda implies it's reliable enough to be confident in it.
"When a user is created and its public keys uploaded to the server, the server signs the public keys. Clients that download the public key then validate the signature of the key against the hardcoded server public key in the client. This ensures a MITM attack trying to use a rogue key pair to impersonate a user will be prevented." This doesn't look good to me. Process implies trusting central server for cryptographic…
"When a user is created and its public keys uploaded to the server, the server signs the public keys. Clients that download the public key then validate the signature of the key against the hardcoded server public key in the client. This ensures a MITM attack trying to use a rogue key pair to impersonate a user will be prevented." This doesn't look good to me. Process implies trusting central server for cryptographic…
FWIW, that's exactly what happens with Verisign (or DigiNotar) when you connect to your banks SSL website…
"When a user is created and its public keys uploaded to the server, the server signs the public keys. Clients that download the public key then validate the signature of the key against the hardcoded server public key in the client. This ensures a MITM attack trying to use a rogue key pair to impersonate a user will be prevented." This doesn't look good to me. Process implies trusting central server for cryptographic…
FWIW, that's exactly what happens with Verisign (or DigiNotar) when you connect to your banks SSL website…