[tor-bugs] #25277 [Webpages]: Publish regex for v3 hidden services

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#25277: Publish regex for v3 hidden services
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 Reporter:  ageisp0lis                           |          Owner:  (none)
     Type:  enhancement                          |         Status:  new
 Priority:  Medium                               |      Milestone:
Component:  Webpages                             |        Version:  Tor:
                                                 |  unspecified
 Severity:  Normal                               |     Resolution:
 Keywords:  hidden services, v3, next-           |  Actual Points:
  generation, regex                              |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by pastly):

 Just dropping by to mention that not all combinations of 56-characters
 long strings of base 32 text are valid v3 onions.

 So you can know that it definitely is NOT an onion service name if it
 doesn't match a simple regex. But you can't know if it definitely IS an
 onion service name with just regex.

 Put simply, a v3 onion address is (1) a 32-byte (not bit) public key, (2)
 a checksum, and (3) a version all encoded together (in that order) in
 base32. The version is always 3 (or 'd' in base32), thus they always end
 in 'd'. In addition, the checksum must work out.

 https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.txt#n2012
 (Section 6 ONIONADDRESS)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25277#comment:6>
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