[Cryptography] Suggestions for wearable wireless technology ?

[Henry Baker]

I'm working with a small medical device company which is making wearable devices.

The problem is: what wireless technologies are there that have the following characteristics:

* Extremely low power when not in use (most of the time)
* Short range (body area network -- ~1 meter)
* High data rates (10-100 Mbits/sec) occasionally -- e.g., in the doctor's office
* Exceedingly robust: waterproof, even at scuba depths, useful in contact sports -- e.g., football; (radio doesn't have to *work* underwater, but it does have to *survive* being underwater)
* Exceedingly secure & private -- e.g., no "Bluetooth beacons" that can be tracked by store monitors or street monitors
* Relatively small & cheap in HW & SW (i.e., no 100MB or 1GB SW stacks!)

Bluetooth -- even Bluetooth Low Energy -- is a horrendous mess, requiring expensive licensing and has very poor security & privacy.

The other low power protocols -- e.g., Zigbee -- don't seem to have security & privacy necessary for a human wearer designed in.

I was thinking about some sort of low power optical signaling which could wake up a wifi radio for brief high bandwidth bursts.  Alternatively, it might be possible to utilize some sort of optical sensor and a high frequency LED to establish a high bandwidth optical link, but what kind of protocol would be ideal?

There still needs to be highly encrypted signaling and the highest quality authentication (e.g., for the doctor's office and/or firmware upgrades).

Any ideas?