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108 lines
3.9 KiB
Plaintext
108 lines
3.9 KiB
Plaintext
Filename: 098-todo.txt
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Title: Proposals that should be written
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Author: Nick Mathewson, Roger Dingledine
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Created: 26-Jan-2007
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Status: Meta
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Overview:
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This document lists ideas that various people have had for improving the
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Tor protocol. These should be implemented and specified if they're
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trivial, or written up as proposals if they're not.
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This is an active document, to be edited as proposals are written and as
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we come up with new ideas for proposals. We should take stuff out as it
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seems irrelevant.
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For some later protocol version.
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- It would be great to get smarter about identity and linkability.
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It's not crazy to say, "Never use the same circuit for my SSH
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connections and my web browsing." How far can/should we take this?
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See ideas/xxx-separate-streams-by-port.txt for a start.
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- Fix onionskin handshake scheme to be more mainstream, less nutty.
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Can we just do
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E(HMAC(g^x), g^x) rather than just E(g^x) ?
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No, that has the same flaws as before. We should send
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E(g^x, C) with random C and expect g^y, HMAC_C(K=g^xy).
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Better ask Ian; probably Stephen too.
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- Length on CREATE and friends
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- Versioning on circuits and create cells, so we have a clear path
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to improve the circuit protocol.
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- SHA1 is showing its age. We should get a design for upgrading our
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hash once the AHS competition is done, or even sooner.
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- Not being able to upgrade ciphersuites or increase key lengths is
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lame.
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- Paul has some ideas about circuit creation; read his PET paper once it's
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out.
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Any time:
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- Some ideas for revising the directory protocol:
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- Extend the "r" line in network-status to give a set of buckets (say,
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comma-separated) for that router.
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- Buckets are deterministic based on IP address.
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- Then clients can choose a bucket (or set of buckets) to
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download and use.
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- We need a way for the authorities to declare that nodes are in a
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family. Also, it kinda sucks that family declarations use O(N^2) space
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in the descriptors.
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- REASON_CONNECTFAILED should include an IP.
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- Spec should incorporate some prose from tor-design to be more readable.
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- Spec when we should rotate which keys
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- Spec how to publish descriptors less often
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- Describe pros and cons of non-deterministic path lengths
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- We should use a variable-length path length by default -- 3 +/- some
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distribution. Need to think harder about allowing values less than 3,
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and there's a tradeoff between having a wide variance and performance.
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- Clients currently use certs during TLS. Is this wise? It does make it
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easier for servers to tell which NATted client is which. We could use a
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seprate set of certs for each guard, I suppose, but generating so many
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certs could get expensive. Omitting them entirely would make OP->OR
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easier to tell from OR->OR.
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Things that should change...
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B.1. ... but which will require backward-incompatible change
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- Circuit IDs should be longer.
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. IPv6 everywhere.
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- Maybe, keys should be longer.
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- Maybe, key-length should be adjustable. How to do this without
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making anonymity suck?
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- Drop backward compatibility.
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- We should use a 128-bit subgroup of our DH prime.
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- Handshake should use HMAC.
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- Multiple cell lengths.
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- Ability to split circuits across paths (If this is useful.)
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- SENDME windows should be dynamic.
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- Directory
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- Stop ever mentioning socks ports
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B.1. ... and that will require no changes
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- Advertised outbound IP?
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- Migrate streams across circuits.
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- Fix bug 469 by limiting the number of simultaneous connections per IP.
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B.2. ... and that we have no idea how to do.
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- UDP (as transport)
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- UDP (as content)
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- Use a better AES mode that has built-in integrity checking,
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doesn't grow with the number of hops, is not patented, and
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is implemented and maintained by smart people.
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Let onion keys be not just RSA but maybe DH too, for Paul's reply onion
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design.
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