On Mon, Jan 31, 2011 at 3:52 PM, Karsten Loesing <karsten.loes...@gmx.net> wrote: > On Mon, Jan 31, 2011 at 03:03:57PM -0500, Ian Goldberg wrote: >> On Mon, Jan 31, 2011 at 08:37:00PM +0100, Karsten Loesing wrote: >> > Here's a sample bridge pool assignment from September 2010 that is >> > sanitized as described above (all IP addresses set to 127.0.0.1, contained >> > fingerprints are SHA-1 hashes of the original fingerprints): >> > >> > http://freehaven.net/~karsten/volatile/bridge-pool-assignment-sample >> > >> > This sample is there, so that everyone gets a better idea of what is meant >> > by a bridge pool assignment. Does anyone object to publishing tarballs of >> > these sanitized bridge pool assignments on the metrics website, so that we >> > (and anyone else) can analyze them? >> >> Is there enough entropy in the things you're hashing to prevent >> reversing the hash? > > Well, I guess so. We're hashing the bridge identity fingerprints. From > dir-spec.txt: > > "fingerprint" fingerprint NL > > [At most once] > > A fingerprint (a HASH_LEN-byte of asn1 encoded public key, encoded in > hex, with a single space after every 4 characters) for this router's > identity key. > > Does this mean we're safe here?
I think we're okay. A censor could in theory correlate this with certificates, if it had them, but I think most automated certificate crawlers will wind up with link certs only, so the censor will need to do their own crawling to find bridges. If we care a lot, we could instead have the sanitization process use some secret X and report H(X|H(ID key)) in place of H(ID key). -- Nick
