[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:  Tor: 0.2.8.x-final
Component:  Tor                 |        Version:
 Severity:  Normal              |     Resolution:
 Keywords:  hs key-observatory  |  Actual Points:
Parent ID:  #17242              |         Points:
  Sponsor:                      |
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Changes (by teor):

 * keywords:  .onion hidden service => hs key-observatory
 * parent:   => #17242
 * milestone:   => Tor: 0.2.8.x-final


Comment:

 Tor already has a field for this, each hidden service descriptor has a
 monotonically strictly increasing sequence number.

 Descriptors created using a stolen key are somewhat more likely to be
 rejected in the first period, if setup naïvely. The newly created hidden
 service will use a sequence number of 1, whereas the existing hidden
 service will have incremented for each descriptor change in the period.

 If we randomised the sequence number, a hidden service could check that
 the descriptor corresponds to the sequence number it posted.

 Alternately, the hidden service could check the hash of the descriptor
 against the one it posted.

 Either of these schemes would have to allow for OnionBalance and similar
 load-balancing schemes.

 A (python-based) ControlPort client could do these checks, maybe that
 would be the best way to implement this feature.

 (See also proposal 224 tickets like #17242.)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17957#comment:1>
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