[tor-talk] WFU, Entry Guards and Service Location Attack

[mirimir]

On 10/05/2013 01:28 PM, Christoph Schulthess wrote:

> Hi everyone,
> 
> I've been thinking and reading a bit about Tor and especially hidden
> servers, now I have a couple of questions:

Better would be creating questions on https://tor.stackexchange.com/ :)

> 1. What are the exact criteria for applying the guard flag to a relay? The
> older blog entry at
> https://blog.torproject.org/category/tags/entry-guardsnames 3 criteria
> with exact numbers but there is a newer post which
> suggests that the system has been changed since 2011.
> 
> 2. How is the Weighted Fractional Uptime number calculated exactly? Could
> you give an quick example? I found one explanation online but when I
> calculated it, I always got quite different numbers than the example that
> was given.
> 
> 3. The Locating-paper mentions three attacks to locate hidden servers and
> the entry guard concept as effective countermeasure. I understand how entry
> guards protect from the predecessor attack and the distance attack, but so
> far I don't see how they prevent the service location attack. Is there
> another countermeasure against that kind of attack or did I miss something?
> 
> Would be great if anyone could help me out.
> 
> Christoph
>