[tor-bugs] #31223 [Core Tor/Tor]: Research approaches for improving the availability of services under DoS

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#31223: Research approaches for improving the availability of services under DoS
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     Reporter:  asn             |      Owner:  (none)
         Type:  defect          |     Status:  new
     Priority:  Medium          |  Milestone:  Tor: 0.4.3.x-final
    Component:  Core Tor/Tor    |    Version:
     Severity:  Normal          |   Keywords:  tor-hs tor-dos
Actual Points:                  |  Parent ID:
       Points:  15              |   Reviewer:
      Sponsor:  Sponsor27-must  |
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 We've been improving the health of the network during onion service DoS,
 but not the onion service availability. This is a task for looking at this
 angle.

 During the related Stockholm session we looked into various approaches
 that could help us towards that goal. Here are some of them:

 - Introducing application-layer anonymous tokens that allow legit clients
 to get priority over DoS attacker
 - PoW approaches like argon2
 - CAPTCHA approaches like introducing a token server giving reCAPTCHA
 tokens
 - Hiding introduction points by rate limiting how quickly clients can find
 them. Valet nodes?
 - Having intros check that clients don't use the same IP over and over.
 Proof-of-existence?
 - Pay bitcoin to introduce

 Each of the above solutions has problems and this is a ticket to
 investigate at least the most promising of them, and attempt to move
 forward with something.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31223>
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