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Proposal idea: Require majority of authorities to vote for consensus parameters
by Sebastian Hahn 22 Feb '11

22 Feb '11

Filename: xxx-param-voting.txt Title: Require majority of authorities to vote for consensus parameters Author: Sebastian Hahn Created: 16-Feb-2011 Status: Draft Overview: The consensus that the directory authorities create may contain one or more parameters (32-bit signed integers) that influence the behavior of Tor nodes (see proposal 167, "Vote on network parameters in consensus" for more details). Currently (as of consensus method 11), a consensus will end up containing a parameter if at least one directory authority votes for that paramater. The value of the parameter will be the low-median of all the votes for this parameter. This proposal aims at changing this voting process to be more secure against tampering by a non-majority of directory authorities. Motivation: To prevent a minority of the directory authorities from influencing the value of a parameter unduly, the majority of directory authorities has to vote for that parameter. This is not currently happening, and it was in fact not uncommon for a single authority to govern the value of a consensus parameter. Design: When the consensus is generated, the directory authorities ensure that a param is only included in the list of params if at least half of the total number of authorities votes for that param. The value chosen is the low-median of all the votes. We don't mandate that the authorities have to vote on exactly the same value for it to be included because some consensus parameters could be the result of active measurements that individual authorities make. Security implications: This change is aimed at improving the security of Tor nodes against attacks carried out by a minority of directory authorities. It is possible that a consensus parameter that would be helpful to the network is not included because not enough directory authorities voted for it, but since clients are required to have sane defaults in case the parameter is absent this does not carry a security risk. Specification: dir-spec section 3.4 currently says: Entries are given on the "params" line for every keyword on which any authority voted. The values given are the low-median of all votes on that keyword. It is proposed that the above is changed to: Entries are given on the "params" line for every keyword on which a majority of authorities (total authorities, not just those participating this vote) voted on. The values given are the low-median of all votes on that keyword. XXX note previous behaviour. The following should be added to the bottom of section 3.4.: * If consensus method 12 or later is used, only consensus parameters that more than half of the total number of authorities voted for are included in the consensus. The following line should be added to the bottom of section 3.4.1.: "12" -- Params are only included if a majority voted for them Compatibility: A sufficient number of directory authorities must upgrade to the new consensus method used to calculate the params in the way this proposal calls for, otherwise the old mechanism is used. Nodes that do not act as directory authorities do not need to be upgraded and should experience no change in behaviour. Implementation: An example implementation of this feature can be found in https://gitweb.torproject.org/sebastian/tor.git, branch safer_params.

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Re: [tor-dev] xxx-draft-spec-for-TLS-normalization.txt
by Nick Mathewson 21 Feb '11

21 Feb '11

Aha. Let's see if I have the tor-dev address right at long long last. Apologies to Peter, who will have received more than one copy of this already. (Apparently , I am told, the "lists." in tor-dev(a)lists.torproject.org is not optional.) On Mon, Feb 21, 2011 at 12:52 PM, Nick Mathewson <nickm(a)freehaven.net> wrote: > On Sun, Feb 20, 2011 at 10:49 PM, Peter Gutmann > <pgut001(a)cs.auckland.ac.nz> wrote: >> Nick Mathewson <nickm(a)freehaven.net> writes: >> >>>Preliminary results suggest that there wasn't actually a crowd here: the >>>reason that we switched the browser DH paramaters in the most recent releases >>>is that the old (standard!) primes were in fact blocked by at least one >>>nation-level censor because we used them. It seems that in practice, if we >>>want to blend with a crowd, we need to use the hardwired DH parameters from >>>mod_ssl. >> >> So the SSL handshake was blocked if you used the Oakley (RFC 2412) DH values? > > Just the 1024-bit one, I would guess (the one in section E.2 of > RFC2412, a.k.a. the one from RFC2409 section 6.2, a.k.a Second Oakley > Group). Or to be precise, we used to use that group, and then we were > blocked, and when we changed to a different group, we weren't. It > might be that they were blocking based on more than one factor, only > one of which was the use of the prime in a TLS ephemeral DH handshake. > >> Is there a server in said location for which access gets blocked that I could >> test against? I'd love to try some variations on SSL handshakes to see what >> gets blocked and what doesn't. > > The use in question was a client in the country trying to connect to a > server outside the country, and the server providing this DH parameter > value. I'll ask our contacts if they can get you shell access there.

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Fw: curvecpclient+curvecpserver alpha test
by Robert Ransom 21 Feb '11

21 Feb '11

See below. Robert Ransom Begin forwarded message: Date: 21 Feb 2011 02:51:21 -0000 From: "D. J. Bernstein" <djb(a)cr.yp.to> To: curvecp(a)list.cr.yp.to Subject: curvecpclient+curvecpserver alpha test Hi everybody, I've posted information about CurveCP at http://curvecp.org; and today's release of NaCl includes command-line curvecpclient and curvecpserver tools. There are many reasons that this curvecpclient+curvecpserver software isn't ready for users yet---among other things, * the software hasn't gone through anywhere near my usual levels of testing and security review; * the software prioritizes simplicity over efficiency in several ways, missing some of the speed that CurveCP can provide; and * the software handles only CurveCP, without HTTPCurve, SMTPCurve, etc. ---but if you're a programmer interested in CurveCP then I think this software is a reasonable starting point for experimentation and further development. ---D. J. Bernstein Research Professor, Computer Science, University of Illinois at Chicago

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Re: [tor-dev] Thoughts on https://trac.torproject.org/projects/tor/wiki/dev/SupportPolicy
by Lucky Green 21 Feb '11

21 Feb '11

On 2011-02-02 09:02, Nick Mathewson wrote: > > On Tue, Jan 25, 2011 at 9:04 AM, Lucky Green <shamrock(a)cypherpunks.to> wrote: >> >> On 2011-01-25 01:09, Erinn Clark wrote: [...] >> >> Erinn, >> >> My feedback is that the Tor Project really, really will want a written >> >> and published policy of how far back an OS is supposed to be supported. >> >> Otherwise, you will get to have this discussion every time a new OS >> >> version is released. >> >> >> >> Industry standard for consumer software that goes into the far corners >> >> of the world is "current and previous major version", which has >> >> different meanings depending on OS. > > > > Hi, Lucky! I generally agree with you, but I do want to point out a > > point that makes me balk at applying your experience without more > > consideration. > > > > It seems to me that the "industry standard for computer consumer > > software" is chosen to serve the goals of the software industry: that > > is, to sell software to people who can pay for it. As a means to that > > end, commercial software enterprises sometimes additionally support > > marginal userbases (those who can't pay, those who can't pay much) in > > order to increase the install base of their software and provide > > positive network effects for their paying customers. > > > > We're in a slightly different position: we're achieving our mission to > > the extent that lots of users -- whether they can pay or not! -- can > > use our software. Also, we want volunteers with free (to them) > > bandwidth to be able to run our server software on the hardware and > > software they have lying around. > > > > I suspect that, when all is said and done, the set of operating > > systems that it makes sense to support in the commercial software > > industry will work out to be almost the same as the ones Tor want to > > support -- but the reasoning is a little different, since industry > > needs to optimize profit-per-developer-hour, and we're trying to > > optimize social-benefit-per-developer-hour. Hmm. My emails on this topic must have been quite poorly written to result in your feedback about them focusing on what I had intended to be little more than a footnote or parenthetical at the very end of the communication thread. I am aware of and concur that Tor's success metrics are different from those of most commercial software vendors. My analysis was entirely focused on helping Tor devise the best OS version support policy possible while assuming Tor's goal of "social-benefit-per-developer-hour". My bad if that was not clear from my writings. Though I am not quite certain what the best path would have been for me to take: omit any references to commercial software development best practices, even in annexes and footnotes, when discussing open source software? Somehow that doesn't strike me as the optimal answer. But be that as it may, I assure you wholeheartedly that my analysis was solely intended to guide Tor and its ecosystem, not that of commercial software development. Either way, even more core to my advice than which particular OS versions to support (the one area where any dichotomy between open source and the commercial world may or may not come in) was my point that Tor needs a written and published OS support policy, agreed-upon by the Tor team. Whichever version support policy the Tor team may arrive at and for whatever reasons. And whether or not the Tor team takes my advice as to which particular versions to support. --Lucky

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Re: [tor-dev] or-dev mailing list migration February 19, 2011
by Andrew Lewman 20 Feb '11

20 Feb '11

And this is complete. Mail archive migration is coming soon. On Sun, 13 Feb 2011 21:37:20 -0500 Andrew Lewman <andrew(a)torproject.org> wrote: > A reminder that this migration occurs this weekend. > > On Mon, 24 Jan 2011 15:28:30 -0500 > Andrew Lewman <andrew(a)torproject.org> wrote: > > > Hello or-dev subscribers, > > > > On February 19, 2011, we are migrating or-dev from or-dev(a)seul.org > > to tor-dev(a)lists.torproject.org. We will migrate your e-mail > > address's subscription to the new list. You will receive a > > confirmation from the new mailing list software on the 19th. > > > > Current or-dev archives will be migrated. Roger plans to leave the > > current archives in place at seul.org as well. > > > > We're using this migration to spread administration out to Tor's > > sysadmin team rather than making Roger do everything himself. The > > secondary benefits of having the lists on the torproject.org domain > > include SSL-enabled login, archives, and easier account management. > > > > You can subscribe to the new list at > > https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev > > > > I will send out a reminder on the day of the migration. > > > > Please e-mail tor-assistants(a)torproject.org with any questions. > > > > Thank you. > > > > > -- Andrew pgp 0x74ED336B

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