Encryption over Hidden Services
rransom.8774 at gmail.com
Fri Aug 6 13:00:12 UTC 2010
On Fri, 6 Aug 2010 03:07:12 -0700
Mike Perry <mikeperry at fscked.org> wrote:
> In the real world, it is disturbingly practical to compute .onion urls
> that have a significantly large number of characters in common with an
> arbitrary target url, in arbitrary positions of the url.
> There was a program called 'shallot' which optimized hidden service
> key generation to accomplish exactly this using THC's Fuzzy
> Fingerprint technique. It seems to exist only in rumor and legend
> these days, but if you would like an arbitrary snapshot of the code
> that calls itself 0.0.1, I can post it somewhere.
> It was originally created for the sake of creating vanity .onion urls.
> However, the author optimized it far enough so that the hash could
> have something like 8 characters in common with a target .onion url,
> in either the prefix, or the suffix, or both, with just a few
> machine-days of computation. Their implementation also only created
> "strong" RSA keys for the resulting .onion urls. If they allowed weak
> key generation for their targets, much more optimization was possible
> (and if your goal is to deceive a user into visiting or chatting with
> your spoofed hidden service, why not use weak keys?).
From the README file for version 0.0.3:
| On my 1.5GHz x86-machine, I get about 500k hashes/sec.
| | chars | ~number of tries | ~time @ 500 KH/s |
| | 6 | 32^6 = 1g | 30 min |
| | 7 | 32^7 = 32g | 1 day |
| | 8 | 32^8 = 1t | 25 days |
| | 9 | 32^9 = 32t | 2.5 years |
Also, it can search for keys whose hashes match an arbitrary regular
expression, not just keys whose hashes have specified characters at the
beginning and end.
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