[tor-bugs] #16645 [Tor]: Write guide about using offline ed25519 keys on relays

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#16645: Write guide about using offline ed25519 keys on relays
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     Reporter:  asn     |      Owner:
         Type:  task    |     Status:  new
     Priority:  normal  |  Milestone:
    Component:  Tor     |    Version:  Tor: 0.2.7
   Resolution:          |   Keywords:  tor-relay doc
Actual Points:          |  Parent ID:
       Points:          |
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Comment (by s7r):

 I will start to write an easy and complete FAQ. My concern is with people
 not reading it more than how to write it. I want to make sure that if
 someone wants to use this feature, he read the documention _before_ (which
 is why I want to keep the FAQ page small, simple, explicit even for non
 technical people, so that it will be read entirely).

 Can we create an ascii-armor version of the encrypted ed25519 master id
 key easily?

 I would like to offer the possibility to store it in as many different
 places as possible: sending it in an email, printing it in a QR code or
 saving a small image of the QR code somwhere, storing it in a cloud
 service (maybe with an optional additional layer of PGP encryption for
 operators who also use PGP). Given the fact that most of relays are
 probably run in datacenters, I don't think many operators can plug a
 storage media in the servers and cut/paste the key, so they will have to
 export it thorugh the internet via a secure channel.

 While discussing with nickm usuability, I was thinking to make Tor ask
 some questions when started (no ed25519 key found, generate one? encrypt
 it? what SigningKeyLifetime? [...]) and to make it also at the same time
 noninteractive, use the defaults if no input from the user within 'n'
 seconds. Thinking more about this approach, I don't think it would be a
 great idea, as it would require more code and will also maybe make the
 operator 'curious' and probably use the feature without reading the entire
 documentation or understanding how it works exactly. Operators playing
 with this feature in a wrong way will affect the network in a bad way. If
 an operator is interested into using this feature, a big clear FAQ / HOWTO
 page will be available and we should limit the possibility for someone
 using this feature without knowing about it or reading the instructions.

 I see 3 major points an operator needs to pay attention to:
 - Don't forget to attend to the relay within the SigningKeyLifetime period
 and create a new signing key + cert. Keeping the master ID key offline
 will not work for relays which run for long time unattended. Better not
 use this feature if you don't have time to attend to the relay as required
 by the SigningKeyLifetime period;

 - Don't lose the master id key - save backups in multiple places.
 Understand that losing this means losing the identity of the relay
 forever. Would require to start a new fresh relay from scratch;

 - Use a strong password and remember it;

 (maybe) don't even allow to use silly passwords like and require min. 8
 chars length, at least one upper case, one lower case, one number and one
 symbol. The tradeoff with this is that we could force the operator to use
 a more complicated password which will be easier to forget (and forgetting
 the password == losing the master id key forever).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16645#comment:1>
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