tor/changes/prop224

  o Major features (next-generation onion services):
    - Tor now supports the next-generation onion services protocol for clients
      and services! As part of this release, the core of proposal 224 has been
      implemented and is available for experimentation and testing by our
      users. This newer version of onion services (v3) features various
      improvements over the legacy system:
        a) Better crypto (replaced SHA1/DH/RSA1024 with SHA3/ed25519/curve25519)
        b) Improved directory protocol leaking less to directory servers.
        c) Improved directory protocol with smaller surface for targeted attacks.
        d) Better onion address security against impersonation.
        e) More extensible introduction/rendezvous protocol.
        f) A cleaner and more modular codebase.

      Furthermore, as part of this update, onion addresses increase in length
      and are now 56 characters long:
         4acth47i6kxnvkewtm6q7ib2s3ufpo5sqbsnzjpbi7utijcltosqemad.onion

      In the future, we will be releasing more options and features but we
      first need a testing period, so that the current codebase matures and
      becomes more robust. Here are some of the features we have planned:
        1) Offline keys for onion services
        2) Advanced client authorization for onion services
        3) Improved guard algorithm for onion services
        4) Next-gen onion service statistics

      Please see our proposal for more details:
        https://gitweb.torproject.org/torspec.git/tree/proposals/224-rend-spec-ng.txt

      The default version for onion services remains v2 (the legacy system)
      until this new codebase gets tested and hardened.

      Service operators who want to experiment with the new system can use the
      'HiddenServiceVersion 3' torrc directive along with the regular onion
      service configuration options.

      We will publish a blog post about this new feature soon! Enjoy!