It's great to see this kind of work published. It is worth noting however that the US government is well aware of these kind of attacks. The Snowdon docs show that the CIA have been performing side-channel analysis since 2012 on the Iphone 4s and Ipad 2: https://theintercept.com/2015/03/10/ispy-cia-campaign-steal-...

Cryptography Research demonstrated this on an ipod in 2011: https://www.youtube.com/watch?v=4L8rnYhnLt8

In any case, great stuff.