[tor-bugs] #17957 [Tor]: Detect stolen onion service key

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#17957: Detect stolen onion service key
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     Reporter:  ess2         |      Owner:
         Type:  enhancement  |     Status:  new
     Priority:  Medium       |  Milestone:
    Component:  Tor          |    Version:
     Severity:  Normal       |   Keywords:  .onion hidden service
Actual Points:               |  Parent ID:
       Points:               |    Sponsor:
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 Would it be possible to add a detection mechanism for stolen onion service
 keys?

 How it could work (I know very little about Tor internals):
 A HSDir could tell the tor client that someone else with the same key
 announced a hidden service just minutes ago.
 To determine that it was someone else, a random number could be sent with
 each announcement of an onion service, and that number randomly changes
 every time tor is restarted. If tor isn't restarted but the HSDir tells
 the announcing tor client that a different number was used to announce the
 onion service before, one could reasonably suspect that the key has been
 compromised. The user could then try to rule out a false positive, and get
 a new key.

 It might be problematic that the HSDir can lie to .onions it doesn't like,
 but as long as no automatic action but the notification is done, this
 shouldn't cause much harm.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17957>
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