[tor-dev] The Onion Name System (OnioNS)

[OnioNS Dev]

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Hello everyone,

I'm the one behind the Onion Name System (OnioNS), a Tor-powered distributed DNS for Tor hidden services. It's been several weeks since my project was selected for the SoP program, and I've finally got around to posting here about it. My project aims to solve the major usability issue that has been with hidden services from the beginning: their un-memorable addresses. I'd like to discuss a bit about how it works, where my project is described, and where I am with the implementation.

Under OnioNS, a hidden service operator can anonymously claim a meaningful domain name for their hidden service (a map between the .tor and .onion pseudo-TLDs) and then transmit it over a Tor circuit to an OnioNS server, which is also a Tor router. The claim propagates across the Tor network. Later, a user may type a .tor domain name into the Tor Browser. My software intercepts this domain, performs a lookup over a Tor circuit to an OnioNS node, and learns the corresponding .onion address. Then it tells the Tor client this, which contacts the HS in the normal way. The result of this process is that a hidden service loads transparently in the Tor browser under a meaningful name.

I introduce several data structures, but the most important one is the Pagechain, a distributed structure of linked Pages. Pages contain Records, Records contain .tor -> onion associations. Anyone who is familiar with blockchains will recognize the behavior and application of this structure immediately. However, here the head of the Pagechain is not managed by miners, but rather by a short-lived subset of Tor nodes called a Quorum. They receive Records and merge them into the Pagechain. At the moment I've decided to use 127 Quorum members and rotate them every week. They are randomly selected, but the process is deterministic; I am using the cached-certs + cached-microdesc-consensus documents, which everyone has, to seed a PRNG that then derives the Quorum. Clients don't need a copy of the Pagechain to use the DNS, but rather they can just rely on their existing trust of the Tor network (including the Quorum and name servers) and verify their signatures on data structures.
Also unlike a blockchain, my Pagechain has a finite length: the oldest Page will eventually drop off, which forces domains to be renewed periodically. I have also introduced mechanisms that 1) allows clients to authenticate the domain name to the hidden service, 2) allow clients to authenticate a denial-of-existence claim from a name server, and 3) prevent name servers from forging .tor -> .onion associations. These vulnerabilities are still generally open on the Internet DNS. I have also tried to minimize networking costs, since Tor circuits are slow.

To reduce CPU and network requirements, I want Tor routers to have Ed25519 keys. Let this project add additional pressure on that item on the to-do list.

Recommended readings:
http://onions55e7yam27n.onion -- the official hidden service for this project, but a work in progress.
https://github.com/Jesse-V/Thesis/blob/master/conference/acm-ccs.pdf -- the ACM paper pending peer review
I no longer recommending reading my original thesis, please use the above links instead.

My prototype can be found here: https://github.com/Jesse-V/OnioNS It's a bit unstable, but it does work once and sometimes twice. Please contact me (kernelcorn on IRC) before running the prototype, I need to ensure that the name server is up before you can try it out. You can also send me registrations over IRC and I can add them in.

I am asking for help with the client-side functionality. I'm currently doing the *.tor interception and lookup resume in connection_edge.c but the software frequently crashes with this approach, (I've learned why) and I'd like to migrate it to Stem for now. I need to intercept .tor domains, pause the lookup (letting the Tor Browser spin), send the hostname over a named pipe or TCP socket, read back a .onion address, then tell Tor to resume the lookup under the .onion address. This way, the HS loads under a .tor domain. All other lookups should load as normal. I've never used Stem before but I understand using it will be a lot easier than hacking Tor. I have Stem up and running now. Any recommendations for what I'm trying to do here?

- --
Jesse V. (kernelcorn)
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