[tor-talk] Practical deanonymization using CPU load covert channels

some_guy123 at Safe-mail.net some_guy123 at Safe-mail.net
Sat Jul 16 11:04:05 UTC 2016

> With two computers connected via Ethernet through a switch, I would
> normally get ping timings of around 250 microseconds.
> However, when the computer being pinged was pegged at 100% CPU on all
> cores, _ping latency would drop to about 170 microseconds._

This is probably caused by power management. Depending on the CPU, C3 wake latency can be >35us, C6 wake latency >100us.

You should try to disable these C-states in the BIOS or kernel:

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