Opened 11 months ago

Last modified 11 months ago

#32670 new enhancement

Provide and use higher resolution padding callback timers

Reported by: mikeperry Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version:
Severity: Normal Keywords: wtf-pad circpad-researchers-want
Cc: Actual Points:
Parent ID: Points:
Reviewer: Sponsor:


During testing, I noticed that the timers.c callbacks could be up to 10 milliseconds late on an otherwise idle Linux laptop tor client. They might be even later on busy relays.

Circuit fingerprinting results may be impacted by this delay. If a deep learning classifier is able to determine padding cells through recognizing this delay, padding will entirely ineffective.

It would be nice to have either high priority timers for things like this, or at least better idle resolution.

We do not yet have enough results to say with certainty if high accuracy padding timers are more important for clients, or for relays.

Child Tickets

Change History (2)

comment:1 Changed 11 months ago by mikeperry

Summary: Provide higher resolution callback timersProvide and use higher resolution padding callback timers

comment:2 Changed 11 months ago by nickm

Step one here is diagnosis. Is this happening because of Libevent's choices of how to interact with the kernel, because of our timing-wheel settings, or something else?

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