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Re: [tor-bugs] #3460 [Tor Hidden Services]: Replay-detection window for HS INTRODUCE2 cells causes HS reachability failures
#3460: Replay-detection window for HS INTRODUCE2 cells causes HS reachability
failures
---------------------------------+------------------------------------------
Reporter: rransom | Owner: rransom
Type: task | Status: needs_review
Priority: normal | Milestone: Tor: 0.2.2.x-final
Component: Tor Hidden Services | Version:
Keywords: | Parent:
Points: | Actualpoints:
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Comment(by nickm):
Okay, I've got some obvious stuff to sort out in my head before I can
review this.
Stupid questions: What if, after we replace an intro point, we
accidentally pick the same intro point later on? What if we stop, then
restart and pick the same intro point? Is it just service key rotation
that keeps this safe? (And am I right in thinking that everybody uses the
introduce format that include service keys?)
Also, it seems that this approach has a nasty possibility where I "just"
make 16K bogus introduce attempts -- I don't need to even do a g^x; I only
need to do the public RSA -- and make you choose a different intro point.
Probably I could keep doing this until you're using an intro point I like.
Not a terribly cheap attack, but could be worth analyzing. Maybe the
right answer is to change only the service key, but keep the same
introduction points until you would otherwise rotate them?
Here's another dumb question: Why take this approach rather than, say,
just incrementing the window from 30 minutes to 12 hours?
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/3460#comment:4>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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