[tor-bugs] #22791 [Core Tor/Tor]: Prop 224 encrypted public key

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#22791: Prop 224 encrypted public key
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 Reporter:  Dbryrtfbcbhgf  |          Owner:
     Type:  defect         |         Status:  closed
 Priority:  High           |      Milestone:  Tor: 0.3.2.x-final
Component:  Core Tor/Tor   |        Version:
 Severity:  Normal         |     Resolution:  invalid
 Keywords:                 |  Actual Points:
Parent ID:                 |         Points:
 Reviewer:                 |        Sponsor:
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Changes (by dgoulet):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 There seems to be many confusion here.

 The `HS-DESC-FIRST-LAYER` is not encrypted differently per client. If you
 don't know the onion address, you can't log the ciphertext _from_ the
 descriptor because you can't get it in the first place without the onion
 address. So the attackers move here is to run a bunch of HSDir and log all
 ciphertext it sees. But because that ciphertext is always the same, I
 don't see how you would correlate this with the number of clients
 visiting...? You can do that by counting the number of descriptor request
 you get for that descriptor and extrapolating by 3 (because 3 directories
 by default).

 Furthermore, that layer *IS* padded but it is ultimately to hide if a
 onion address is using client authorization and the number of introduction
 points. See section 2.5.1.1.:

 {{{
    Before encryption the plaintext is padded with NUL bytes to the nearest
    multiple of 10k bytes.
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22791#comment:1>
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