Opened 6 years ago

Closed 4 years ago

Last modified 3 years ago

#8950 closed defect (duplicate)

Comments on the formula calculating the number of Introduction Points

Reported by: asn Owned by:
Priority: Medium Milestone:
Component: Core Tor/Tor Version:
Severity: Keywords: tor-hs
Cc: hellais Actual Points:
Parent ID: Points:
Reviewer: Sponsor:

Description

While looking at #3521 with hellais, we noticed that popular hidden services only have 3 introduction points, which is supposed to be the minimum number of introduction points a hidden service could have.

Maybe the formula at https://gitweb.torproject.org/tor.git/blob/ab3d5c049032651a9c9164262f9a8f81de9709d4:/src/or/rendservice.c#l1001 is not working very well, or Tor underestimates its own popularity, or all those services use an older version of tor.

As an example, here is the HS descriptor of DDG:

rendezvous-service-descriptor 4twtd2fpuz2xakzqpiuehdfp63ff2jp4
version 2
permanent-key
-----BEGIN RSA PUBLIC KEY-----
MIGJAoGBAJ/SzzgrXPxTlFrKVhXh3buCWv2QfcNgncUpDpKouLn3AtPH5Ocys0jE
aZSKdvaiQ62md2gOwj4x61cFNdi05tdQjS+2thHKEm/KsB9BGLSLBNJYY356bupg
I5gQozM65ENelfxYlysBjJ52xSDBd8C4f/p9umdzaaaCmzXG/nhzAgMBAAE=
-----END RSA PUBLIC KEY-----
secret-id-part wpuxu5zpsgzgoqp7dq5yjay26vhachrx
publication-time 2013-05-23 19:13:59
protocol-versions 2,3
introduction-points
-----BEGIN MESSAGE-----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-----END MESSAGE-----
signature
-----BEGIN SIGNATURE-----
R8seD+2Xeb5zXOK3j3LDHDDskkGxRVjJ8u3EqoFEiLXfSdxjZ3tRJSlXj2WbWhHA
FAGrTZgzGcAr4ma9kRatchsbKEmIQW5cnsY8rk+gJwW+SHewFvV/iAGYLQ7pQ6dD
6+P0sPkLC47n1mvLFp81ie/WJqMGKDdZg1vS7FhATrI=
-----END SIGNATURE-----

Child Tickets

Change History (10)

comment:1 Changed 6 years ago by asn

Cc: hellais added

comment:2 Changed 6 years ago by arma

See also #4862

comment:3 Changed 5 years ago by nickm

Milestone: Tor: 0.2.5.x-finalTor: 0.2.???

comment:4 Changed 5 years ago by asn

It might also be worth pondering whether we actually want this feature. If this feature works, an adversary can get a very rough approximation on the number of introductions an HS has performed.

I haven't done the math, to see how accurate such an approximation can be, but it's obvious that busy HSes will be easily distinguished from idle HSes.

comment:5 Changed 5 years ago by hellais

I wrote a quick tool to enumerate the HS descriptors of a list of hidden services and found something quite surprising (here you can find the hackish script that does it: https://gist.github.com/hellais/a1a63df6e9f4958c9ab0).

While most do indeed have 3 intro points I stumbled into one that had 7. If somebody is interested I can give the output of the run of the tool, but you can also do it yourself by compiling the above branch of tor and giving it as list of hidden services the list of most popular HS's by ahmia (https://ahmia.fi/stats/viewer).

comment:6 Changed 5 years ago by hellais

I did some statistics on the number of intro points of the hidden services listed by ahmia.fi.

Here is what came out:

Intro point count: hidden service count
9: 1
8: 2
4: 2
3: 1315
2: 14

comment:7 Changed 4 years ago by asn

Closing this in favor of #4862

comment:8 Changed 4 years ago by asn

Resolution: duplicate
Status: newclosed

comment:9 Changed 3 years ago by teor

Milestone: Tor: 0.2.???Tor: 0.3.???

Milestone renamed

comment:10 Changed 3 years ago by nickm

Milestone: Tor: 0.3.???

Milestone deleted

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