[tor-talk] How evil is TLS cert collection?

Mike Perry mikeperry at fscked.org
Tue Mar 22 00:09:38 UTC 2011


Thus spake Robert Ransom (rransom.8774 at gmail.com):

> On Sun, 20 Mar 2011 17:58:06 -0700
> Mike Perry <mikeperry at fscked.org> wrote:
> 
> > However, I'm not sure that this is going to work for Tor Browser
> > Bundle users (which ships with HTTPS Everywhere) who may have the TBB
> > on readonly USB keys or live cds.  They may end up being asked each
> > time they start.
> > 
> > Is this a decent compromise? The other option is to not even bother to
> > ask users who have a working tor installed, on the assumption that
> > since we can submit certs through tor, it is always safe to do so. We
> > may end up doing this instead of always asking them. Is this wrong? If
> > so, why?
> 
> This ???phone-home??? behaviour is not safe for users who browse the web
> over Tor until proposal 171 is implemented in Tor.  At best, it would
> *only* fragment the anonymity set of Tor users.

The problem with 171 (SOCKS username/password to split streams across
different circuits, for those playing at home) is that Firefox also
lacks username and password fields in the proxy APIs for SOCKS, so we
cannot do this for anyone except for TBB users.

But, if the EFF runs an exit enclave at observatory.eff.org, shouldn't
this solve the same-circuit correlation problem? Tor should prefer
using that exit enclave in all cases when it is up in this case.


-- 
Mike Perry
Mad Computer Scientist
fscked.org evil labs
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