These bugs is a big deal. I even had to answer customer questions on them. Interesting how you can use the cycle counter to deduct information out of that channel, forming a side-channel.
Adding random jitter only slows down the attack, as the average bias difference won't change. Cheers, Magnus On 01/07/2018 03:53 PM, David J Taylor via time-nuts wrote: > From: David > > Possibly not of immediate concern to time-nuts but an article had some > trigger words for them in the initial fixes to the much publicised > problems with Intel/AMD/ARM etc : > > "After these changes, the time stamp returned by |performance.now| will > be less precise due to lower resolution. Some browsers are going a step > further and degrade the accuracy by adding a random jitter." > > https://hackaday.com/2018/01/06/lowering-javascript-timer-resolution-thwarts-meltdown-and-spectre/ > > > meltdown/spectre background > https://www.theregister.co.uk/2018/01/04/intel_amd_arm_cpu_vulnerability/ > ================================ > > David, > > This API appears only to affect browsers. > > On my Windows systems most have been patched, and I see no visible > difference on either PPS-synced, LAN-synched or Wi-Fi devices as > recorded by NTP. One PC showed an increase in CPU usage, but other PCs > performing similar tasks have not. That same PC showed a doubling of > jitter from less than 2 microseconds to less than 4 microseconds. It's > an i5-4460 Haswell processor. > > http://www.satsignal.eu/mrtg/harstad-cpu-week.png > > Cheers, > David _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
