This list of open Tor proposals is based on one I sent out in May of last year. Since I'd like to do this more regularly, I have added to each description the date when I wrote it. Most of the summaries from older proposals are unchanged since last May; the later ones in the list for 6/2012 I wrote pretty quickly since I want to get out the door tonight for an appointment, but I want to send this list out without further delay.

OPEN, DRAFT, AND ACCEPTED PROPOSALS:

117 IPv6 exits

IPv6 is still the future, but now it's the kind of future that's unevenly distributed. It's time to do this one so that IPv6 traffic can be sent over Tor.

It needs updating to work properly with microdescriptors; it also has some open questions about DNS. (6/2012)

127 Relaying dirport requests to Tor download site / website

The idea here was to make it easier to fetch and learn about Tor by making it easy for relays to automatically act as proxies to the Tor website. It needs more discussion, and there are some significant details to work out. It's not at all clear whether this is actually a good idea or not. (5/2011)

131 Help users to verify they are using Tor

Here's a proposal for making a torcheck-like website more reliable. If anybody wants to pick it up (especially somebody working on torcheck) and see whether it should be reopened or rejected, that would be a fine thing. (5/2011)

132 A Tor Web Service For Verifying Correct Browser Configuration

This proposal was meant to give users a way to see if their browser and privoxy (yes, it was a while ago) are correctly configured by running a local webserver on 127.0.0.1. I'm not sure the status here. (5/2011)

133 Incorporate Unreachable ORs into the Tor Network

This proposal had an idea for letting ORs that can only make outgoing connections still relay data usefully in the network. It's something we should keep in mind, and it's a pretty neat idea, but it radically changes the network topology. Anybody who wants to analyze new network topologies should definitely have a look. (5/2011)

140 Provide diffs between consensuses

This proposal describes a way to transmit less directory traffic by sending only differences between consensuses, rather than the consensuses themselves. It is mainly languishing for lack of an appropriately licensed, well-written, very small, pure-C implementation of the "diff" and "patch" algorithms. (The good diffs seem to be GPL (which we can't use without changing Tor's license), or spaghetti code, or not easily usable as a library, or not written in C, or very large, or some combination of those.) (5/2011)

141 Download server descriptors on demand

The idea of this proposal was for clients to only download the consensus, and later ask nodes for their own server descriptors while building the circuit through them. It would make each circuit more time-consuming to build, but make bootstrapping much cheaper.

Microdescriptors obsolete a lot of this proposal, and present some difficulties in using in a way compatible with it. (6/2012)

143 Improvements of Distributed Storage for Tor Hidden Service Descriptors

Here's a proposal from Karsten about making the hidden service DHT more reliable and secure to use. It could use more discussion and analysis. (5/2011)

144 Increase the diversity of circuits by detecting nodes belonging the same provider

This is a version of the good idea, "Let's do routing in a way that tries to keep from routing traffic through the same provider too much!" There are complex issues here that the proposal doesn't completely address, but I think it might be a fine idea for somebody to see how much more we know now than we did in 2008, particularly in light of the relevant paper(s) by Matt Edmann and Paul Syverson. (5/2011)

145 Separate "suitable as a guard" from "suitable as a new guard"

Currently, the Guard flag means both "You can use this node as a guard if you need to pick a new guard" and "If this node is currently your guard, you can keep using it as a guard." This proposal tries to separate these two concepts, so that clients can stop picking a router once it is full of existing clients using it as a guard, but the clients currently on it won't all drop it.

It's not clear whether this has anonymity issues, and it's not clear whether the imagined performance gains are actually worthwhile. (5/2011)

146 Add new flag to reflect long-term stability

From time to time we get the idea of having clients ship with a reasonably recent consensus (or a list of directory mirrors), so instead of bootstrapping from one of the authorities, they can bootstrap from a regular directory cache. The problem here is that by the time the client is run, most of the directory mirrors will be down or will have changed their IP. This proposal tries to address that.

It needs analysis based on behavior of actual routers on the network to see whether it could work, and what parameters might work.

Nevertheless, we should really do something like this, so that we can ship a list of initial directory mirrors with Tor (possibly via the "fallback consensus" deisgn), so that new bootstrapping Tor clients don't all hammer the directory authorities. (6/2012)

147 Eliminate the need for v2 directories in generating v3 directories

This proposal explains a way that we can phase out the vestigial use of v2 directory documents in keeping authorities well-informed enough to generating the v3 consensus. It's still correct; somebody should implement it before the v2 directory code rots any further. (5/2011)

156 Tracking blocked ports on the client side

This proposal provides a way for clients to learn which ports they are (and aren't) able to connect to, and connect to the ones that work. It comes with a patch, too. It also lets routers track ports that _they_ can't connect to.

I'm a little unconvinced that this will help a great deal: most clients that have some ports blocked will need bridges, not just restriction to a smaller set of ports. This could be good behind restrictive firewalls, though.

The router-side part is a little iffy: routers that can't connect to each other violate one of our network topology assumptions, and even if we do want to track failed router->router connections, the routers need to be sure that they aren't fooled into trying to connect repeatedly to a series of nonexistent addresses in an attempt to make them believe that (say) they can't reach port 443.

This one is a paradigmatic "open" proposal: it needs more discussion. The patch probably also needs to be ported to 0.2.3.x; it touches some code that has changed. (5/2011)

157 Make certificate downloads specific

This proposal added cross-certification and signing-key-specific download URLs for directory authority certificates. It is IIRC mostly implemented on the server side; there are just some SHOULDs that we should turn into MUSTS if all sufficiently old authority certificates are now obsolete, and a client-side portion that we need to implement. (6/2012)

159 Exit Scanning

This is an overview of SoaT, with some ideas for how to integrate it into Tor. (5/2011)

162 Publish the consensus in multiple flavors

The initial proposal here is done, but more work is needed for forward-compatibility: we'd like to have caches be willing to cache and serve consensus flavors which they do not currently recognize. (6/2012)

164 Reporting the status of server votes

This proposal explains a way for authorities to provide a slightly more verbose document that relay operators can use to diagnose reasons that their router was or was not listed in the consensus. These documents would be like slightly more verbose versions of the authorities' votes, and would explain *why* the authority voted as it did. It wouldn't be too hard to implement, and would be a fine project for somebody who wants to get to know the directory code. (5/2011)

165 Easy migration for voting authority sets

This is a design for how to change the set of authorities without having a flag day where the authority operators all reconfigure their authorities at once. It needs more discussion. One difficulty here is that we aren't talking much about changing the set of authorities, but that may be a chicken-and-egg issue, since changing the set is so onerous.

If anybody is interested, it would be great to move the discussion ahead here. (5/2011)

168 Reduce default circuit window

This proposal reduces the default window for circuit sendme cells. I think it's implemented, isn't it? If so, we should make sure that tor-spec.txt is updated and close it.XXXXXXX (5/2011)

172 GETINFO controller option for circuit information 173 GETINFO Option Expansion

These would help controllers (particularly arm) provide more useful information about a running Tor process. They're accepted and some parts of 173 are even implemented: somebody just needs to implement the rest. (5/2011)

175 Automatically promoting Tor clients to nodes

Here's Steven's proposal for adding a mode between "client mode" and "relay mode" for "self-test to see if you would be a good relay, and if so become one." It didn't get enough attention when it was posted to the list; more people should review it. (5/2011)

177 Abstaining from votes on individual flags

Here's my proposal for letting authorities have opinions about some (flag,router) combinations without voting on whether _every_ router should have that flag. It's simple, and I think it's basically right. With more discussion and review, somebody could/should build it for 0.2.4.x, I think. (6/2012)

182 Credit Bucket

This proposal suggests an alternative approach to our current token-bucket based rate-limiting, that promises better performance, less buffering insanity, and a possible end to double-gating issues. (6/2012)

185 Directory caches without DirPort

The old HTTP directory port feature is no longer used by clients and relays under most circumstances. The proposal explains how we can get rid of the requirement that non-bridge directories have an open directory port. (6/2012)

186 Multiple addresses for one OR or bridge

This one is partially implemented, in that bridges can have IPv6 addresses. Still to go: we need to let ORs have IPv6 addresses too. Undecided: is one IPv4 and one IPv6 enough for anybody? (6/2012)

188 Bridge Guards and other anti-enumeration defenses

This proposal suggests some ways to make it harder for a relay on the Tor network to enumerate a list of Tor bridges. Worth investigating and possibly implementing. (6/2012)

189 AUTHORIZE and AUTHORIZED cells 190 Bridge Client Authorization Based on a Shared Secret 191 Bridge Detection Resistance against MITM-capable Adversaries

Proposal 187 reserved the AUTHORIZE cell type; these proposals suggests how it could work to try to make it harder to probe for Tor bridges. They need more alternatives and attention, and possibly some revision and analysis. (6/2012)

192 Automatically retrieve and store information about bridges

This proposal gives an enhancement to the bridge information protocol, where clients remember more things about bridges, and are able to update what they know about them over time. Could help a lot with bridge churn. (6/2012)

194 Mnemonic .onion URLs

Here's one of several competing "let's make .onion URLs human-usable" proposals. This one makes sentences using a fixed map. (6/2012)

195 TLS certificate normalization for Tor 0.2.4.x

Here's the followup to proposal 179, containing all the parts of proposal 179 that didn't get built, and a couple of other tricks besides to try to make Tor's default protocol less detectable. I'm pretty psychoed about the part where we let relays drop in any any self-signed or CA-issued certificate that they like. (6/2012)

196 Extended ORPort and TransportControlPort

Here are some remaining pieces of the pluggable transport protocol that give Tor finer control over the behavior of its transports. (6/2012)

197 Message-based Inter-Controller IPC Channel

This proposal is for an architectural enhancement in Tor deployments, where Tor coordinates communications between the various programs (Vidalia, TorBrowser, etc) that are using it. (6/2012)

198 Restore semantics of TLS ClientHello

Partially implemented. We have the new client behavior in place in 0.2.3.x, but not the new server behavior which it permits. (6/2012)

199 Integration of BridgeFinder and BridgeFinderHelper

Here's a proposal for how Tor can integrate with a client program that finds bridges for it. (6/2012)

200 Adding new, extensible CREATE, EXTEND, and related cells

We'd like to moved to better authentication and key agreement mechanisms in future versions of Tor. This proposal gives us an extensible replacement for our current CREATE/CREATED cell mechanism. (6/2012)

201 Make bridges report statistics on daily v3 network status requests

Here's a proposal for bridges to better estimate the number of bridge users. (6/2012)