[Cryptography] Business opportunities in crypto

[Jerry Leichter]

> All of your 'wireless window-open/window-break' detectors have to communicate with some alarm device; it is insane for an alarm system to 'publish' an SSID which can be hacked 24/7 by a battery-powered Raspberry Pi device left in a tree in your yard....
So lets think about this:  WiFi networks use cryptographic protocols - with authentication based on pre-shared secrets or something like Radius - to control access, and then establish keys to encrypt the data exchanged.  You don't trust those to be sufficient, which is arguably a reasonable position to take given the long history of successful attacks.

But you can add security on top of the link-level protocols.  To add a new device, you want some mechanism that's sufficiently secure - physical connection, NFC connection, human reading information from and entering information into the devices - that allows the new device and the AP to agree on authentication information.  That information would be used when a device connects at the link level to control whether it's allowed to stay on and use the WiFi network or is simply kicked off.  In fact, there are plenty of devices - used in hotels, for example - that already do this in a simple-minded way.

We're treating the underlying WiFi as completely insecure and establishing our own encrypted tunnel on top of it.  We don't even need to set up any encryption at the link level - we can just leave the link level open.

None of this requires any novel cryptography or protocol; none of it requires changing the low-level chips that implement the current over-the-air protocols.

Yes, your AP continues to broadcast an SSID - but if only your pre-authorized devices can effectively connect to it, why does that matter?

Now, getting this kind of thing installed in devices like window sensors is going to take some doing.  But since it's all "over the top" it's a hell of a lot easier than getting changes into the WiFi standards and then waiting years for new chips to implement it.  (Meanwhile, maybe the next set of WiFi standards will actually be secure:  WPA2 is a lot better than earlier protocols, but yes, it's still not there.)

In fact, there's probably some stuff like this (of varying quality/security) in the protocols for connecting home control devices.  Perhaps one of them is already "good enough."
                                                        -- Jerry