[tor-bugs] #10887 [Obfsproxy]: ScrambleSuit should make it easy for bridge admins to learn password

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#10887: ScrambleSuit should make it easy for bridge admins to learn password
-------------------------+-------------------------------------------------
     Reporter:  phw      |      Owner:  phw
         Type:           |     Status:  needs_revision
  enhancement            |  Milestone:
     Priority:  normal   |    Version:
    Component:           |   Keywords:  scramblesuit, password, shared
  Obfsproxy              |  secret
   Resolution:           |  Parent ID:
Actual Points:           |
       Points:           |
-------------------------+-------------------------------------------------

Comment (by asn):

 I fixed the above errors and another one (I caught `b32decode()`
 exceptions) and it can be found in `bug10887` in my repo.

 Unfortunately, it still doesn't work perfectly:
 {{{
 # cat pt_state/scramblesuit/server_descriptor
 Bridge scramblesuit 0.0.0.0:33647
 password=S5JY6IRCLLNEGTWBWZMYVIXHFWTITZBE
 }}}
 That's because the bindaddr that is passed from Tor is `0.0.0.0`
 (`IPADDR_ANY`):
 {{{
  'config': {'ORPort': ('127.0.0.1', 42331),
             'allTransportsEnabled': False,
             'authCookieFile': None,
             'extendedORPort': None,
             'managedTransportVer': ['1'],
             'serverBindAddr': {'obfs3': ('0.0.0.0', 40674),
                                'scramblesuit': ('0.0.0.0', 33647)},
             'serverTransportOptions': None,
             'stateLocation': '/usr/local/var/lib/tor2/data/pt_state/',
             'transports': ['obfs3', 'scramblesuit']},
 }}}

 However, I'm still tempted to merge this since it's the only way for
 people to get their automatically-generated passwords. However, maybe we
 should remove the whole Bridge line and just leave the password bit, so
 that we don't give users the illusion that that bridge line would actually
 work.

 Also, on my way to fixing the above, I set the default state directory in
 external mode to be the current working directory. Is this a very bad idea
 that will open us to race conditions/symlink attacks etc.? Probably better
 than setting it to `/tmp/`.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/10887#comment:11>
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