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tor-spec: clean-ups and a new proposal (357) related to use of KH.

Merged tor-spec: clean-ups and a new proposal (357) related to use of KH.
nickm/torspec:kh_clarification into main
1 unresolved thread
Merged Nick Mathewson requested to merge nickm/torspec:kh_clarification into main
1 unresolved thread

In this branch:

  • We clean up some of our usage of CREATE, to make sure that "CREATE" never means "CREATE or CREATE2".
  • We clarify some points about the generation and use of the KH field.
  • We add a new proposal for a better way to use KH in the future.

Closes #191 (closed).

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Merge request pipeline #262528 passed

Stage: test

Merge request pipeline passed for 1704f527

Approved by
David Goulet

Merged by Nick MathewsonNick Mathewson 3 weeks ago (Mar 27, 2025 7:10pm UTC)

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Pipeline #262652 passed

Stage: test
Stage: deploy

Pipeline passed for 08f09290 on main

Deployed to produ‎ction‎ 3 weeks ago
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proposals/357-circ-key-exporters.md 0 → 100644
46 - S (customization string) as a customization string starting with "Tor:"
47 - L (the output length) as desired.
48
49 We denote this exported secret as:
50
51 ```
52 CircExporter(Circuit[Hop], Custom, Len)
53 = cSHAKE128(X=Circuit[Hop].KH, L=Len, N="", C=Custom)
54 ```
55
56 > For example, in the future when we're computing our MAC
57 > for an ESTABLISH\_INTRO message,
58 > instead of using KH directly as our MAC key,
59 > we might use
60 > `CircExporter(Circuit[Hop], "Tor:ESTABLISH_INTRO MAC", 32)`
61 > as our MAC key.
  • David Goulet
    David Goulet @dgoulet
    Owner

    So does this mean we'll have to reserve in our spec the namespace for every places that requires a KH?

    In other words, reserve the ESTABLISH_INTRO_MAC string.

  • Nick Mathewson
    Nick Mathewson @nickm
    Author Owner

    So, there's only one place that uses KH right now, since TAP is dead. But yes, in the future we'll need to make sure we use different customization strings for every place that uses KH.

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  • David Goulet approved this merge request

    approved this merge request

  • Nick Mathewson merged

    merged

  • Nick Mathewson mentioned in commit 08f09290

    mentioned in commit 08f09290

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