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Steinar H. Gunderson

Signal is a pretty amazing app; it manages to combine great security with great simplicity. (It literally takes two minutes, even for an unskilled user, to set it up.)

I looked at the Wikipedia article, and the list of properties the protocol provides is impressive; I had hardly any idea you would even want all of these. But I've tried to decode what they actually mean:

(There are more guarantees and features for group chat.)

Again, it's really impressive. Modern cryptography at its finest.

My only two concerns is that it's too bound to telephone numbers (you can't have the same account on two devices, for instanceit very closely mimics the SMS/MMS/POTS model in that regard), and that it's too clumsy to verify public keys for the IM part. It can show them as hex or do a two-way QR code scan, but there's no NFC support, and there's no way to read e.g. a series of plaintext words instead of the fingerprint. (There's no web of trust, but probably that's actually for the better.)

I hear WhatsApp is currently integrating the Signal protocol (or might be done alreadyit's a bit unclear), but for now, my bet is on Signal. Install it now and frustrate NSA. And get free SMS/MMS to other Signal users (which are growing in surprising numbers) while you're at it. :-)

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