[tor-bugs] #20573 [Core Tor/Tor]: The build_mac() function in hs_descriptor.c should be made generic for the entire code base

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#20573: The build_mac() function in hs_descriptor.c should be made generic for the
entire code base
-------------------------------------------------+-------------------------
 Reporter:  dgoulet                              |          Owner:  dgoulet
     Type:  enhancement                          |         Status:
                                                 |  accepted
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.0.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tor-hs, prop224, crypto,             |  Actual Points:
  TorCoreTeam201611                              |
Parent ID:                                       |         Points:  0.2
 Reviewer:                                       |        Sponsor:
                                                 |  SponsorR-can
-------------------------------------------------+-------------------------

Comment (by dgoulet):

 More information. Turns out that the one in #19043 is different as it
 doesn't take the key/iv length in the construction and is called "HMAC"
 which is not entirely accurate. So what I propose here is that in the
 process of reviewing #19043, we can take this branch as a fixup commit for
 #19043 or once merged upstream, this ticket will become "fix upstream with
 better version of the function".

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20573#comment:4>
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