No, I meant the preventive measures. Would encryption be such a big battery-hog that they preferred security through "obscurity" or did they just overlook the fact that those devices were broadcasting users' keystrokes to the open air? It's unjustifiable in either case but just wondering. (BTW I also don't get the down-vote. Did I say something unrelated?)
The datasheet for the nRF24LE1 talks about it's AES encryption/decryption accelerator (section 15) and thermal noise random number generator (section 16), but the power consumption specs (section 26.1) talk about the rng using 0.5mA and don't even mention the AES hardware (even though they list other modules all the way down to 0.5uA). The RX/TX modules use over 10mA, so an order of magnitude more than the hardware RNG, and possibly 4 orders of magnitude more than the AES hardware.
I doubt the encryption would even register in battery life - completely obscured by the power consumed by the TX/RX modules.
