[tor-relays] descriptor-id calc tool?

nusenu nusenu at openmailbox.org
Tue Feb 28 02:09:00 UTC 2017

>> Is there a tool out there that tells me which HSDir is/will probably be
>> responsible for a given onion address (and at what time)?
> There's no tool, unless you can reverse SHA1.
> (Or brute-force a set of popular onion addresses.)

I probably was not very clear in my question. I'm not aiming for the
reverse path, just the normal calculation a tor client does given an
onion address but instead of just calculating the current descriptor-id,
print descriptor-ids for the future N days for onion address M (for the
pre-prop224 world).

> In short, it's the first 3 fingerprints following descriptor-id:
> permanent-id = H(public-key)[:10]
> descriptor-id = H(permanent-id | H(time-period | descriptor-cookie | replica))
> where H is SHA1.

> The spec is:
> https://gitweb.torproject.org/torspec.git/tree/rend-spec.txt#n222
> https://gitweb.torproject.org/torspec.git/tree/rend-spec.txt#n505
> The implementation is:
> https://gitweb.torproject.org/tor.git/tree/src/or/rendcommon.c#n127

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