That's really interesting. But the leaked information doesn't need to be collected at anything close to clock-cycle sampling periods. For example, there have b

That's really interesting. But the leaked information doesn't need to be collected at anything close to clock-cycle sampling periods. For example, there have been successful timing attacks demonstrated from sampling only the time taken by the overall private key operation (millseconds). Note that these guys demonstrated a side channel attack with an ultrasonic microphone. Yes, the standard assumption is that an attacker will be able to prompt the server to perform a large number of private key operations at predictable times. This is not unrealistic, it usually only takes a half-dozen TCP packets or so to get a web server to do it immediately. (e.g. http://thehackerschoice.wordpress.com/2011/10/24/thc-ssl-dos/ http://thehackerschoice.wordpress.com/2011/10/24/thc-ssl-dos... ) This paper discusses some effective attacks on LED leakage using telescopes. http://www.ma.rhul.ac.uk/static/techrep/2011/RHUL-MA-2011-07.pdf http://www.ma.rhul.ac.uk/static/techrep/2011/RHUL-MA-2011-07... : "A practical upper boundary on data rates by optical emanations was estimated at 10 Mbps (Megabits per second), but they thought that greater data rates may be feasible."