[tor-bugs] #8240 [Tor]: Raise our guard rotation period

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#8240: Raise our guard rotation period
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     Reporter:  arma     |      Owner:
         Type:  defect   |     Status:  new
     Priority:  major    |  Milestone:  Tor: 0.2.???
    Component:  Tor      |    Version:
   Resolution:           |   Keywords:  tor-client needs-proposal
Actual Points:           |  023-backport unfrozen
       Points:           |  Parent ID:
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Comment (by amj703):

 Replying to [comment:42 asn]:
 > To share Mike's concerns here, I had a long discussion with Paul about
 this during the latest dev meeting. He feels that increasing the guard
 lifetime to 9 months makes certain attacks much more plausible.
 >
 > This is especially the case for hidden services, where guard discovery
 attacks are easy. I feel persuaded that we should plug these attacks, or
 make them harder to succeed, before increasing the lifetime here.
 >
 > He was also afraid of the effects of this to regular Tor clients as
 well, since after we moved from 3 to 1 guard, the middle nodes can link
 clients to  their guards more reliably. He is afraid that this might allow
 profiling of specific users, etc.
 >
 > I think all the above means, "more research is required".

 I disagree with this course of action. We know of a clear threat due to
 passive surveillance that can be mitigated by increasing the guard
 rotation period. We don't know exactly how this might balance with active
 attacks that involve guard compromise, targeted surveillance, or middle-
 relay linking. Rather than do nothing because you don't know everything, I
 would do something to fix the thing that you do know about. Also, I think
 Paul's concerns are unlikely to argue strongly for or against increasing
 the guard rotation period, because they will depend strongly on adversary
 properties that we know nothing about, such as the speed of targeted
 compromise.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/8240#comment:44>
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