[tor-bugs] #18119 [Tor]: .onion domain names can be really short

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#18119: .onion domain names can be really short
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 Reporter:  azazar                 |          Owner:
     Type:  enhancement            |         Status:  closed
 Priority:  Medium                 |      Milestone:  Tor: very long term
Component:  Tor                    |        Version:
 Severity:  Normal                 |     Resolution:  wontfix
 Keywords:  tor-hs needs-proposal  |  Actual Points:
Parent ID:                         |         Points:
  Sponsor:                         |
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Comment (by azazar):

 Replying to [comment:13 yawning]:
 > Replying to [comment:11 azazar]:
 > > `spacebookcorewww.onion` won't be translated at all, since it already
 contains 16 characters. And the chance of address collision for shortened
 names is absolutely equal to complete 16-character addresses collision
 chance(you'll have to use vanity generator for getting shorter names
 anyway).
 >
 > Sigh. It was an example that I figure would have been obvious, but fine
 I'll be explicit and use a real domain.
 >
 > Entering `facebookcorewww.onion` should fail, and ideally without
 hitting up the HSDirs. (The real HS being `facebookcorewwwi.onion`).

 It will fail, unless someone is able to bruteforce secret for
 `facebookcorewwwa.onion`(which is resolved from `facebookcorewww.onion`).
 And this isn't easier, than bruteforcing hash for
 `facebookcorewwwi.onion`(difficulty of those tasks are exactly equal).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18119#comment:14>
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