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commit 33308845cec54bfc0096b8ea0339a8ff183aa1b1 Author: Nick Mathewson nickm@torproject.org AuthorDate: Wed Mar 22 14:22:28 2023 -0400
{rend,tor}-spec: clarify linkspec ID multiplicity issues
We were previously a bit unclear on how to handle multiple linkspecs of type ed25519, and our spec didn't actually permit Tor's current behavior.
Now we say that both Ed25519 ID and Legacy ID linkspecs MUST appear at most once in a list of linkspecs, and that parties SHOULD enforce this.
This is "problem 1" on torspec#193. --- rend-spec-v3.txt | 11 ++++++----- tor-spec.txt | 6 ++++-- 2 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/rend-spec-v3.txt b/rend-spec-v3.txt index 3f76824..757fc1a 100644 --- a/rend-spec-v3.txt +++ b/rend-spec-v3.txt @@ -238,7 +238,7 @@ Table of contents: LSPEC (Link specifier) [LSLEN bytes]
Link specifier types are as described in tor-spec.txt. Every set of - link specifiers MUST include at minimum specifiers of type [00] + link specifiers SHOULD include at minimum specifiers of type [00] (TLS-over-TCP, IPv4), [02] (legacy node identity) and [03] (ed25519 identity key).
@@ -1380,7 +1380,7 @@ Table of contents: point section]
The link-specifiers is a base64 encoding of a link specifier - block in the format described in BUILDING-BLOCKS. + block in the format described in [BUILDING-BLOCKS] above.
As of 0.4.1.1-alpha, services include both IPv4 and IPv6 link specifiers in descriptors. All available addresses SHOULD be @@ -1392,8 +1392,9 @@ Table of contents: recognize; instead, it should use them verbatim in its EXTEND request to the introduction point.
- The client MAY perform basic validity checks on the link - specifiers in the descriptor. These checks SHOULD NOT leak + The client SHOULD perform the basic validity checks on the link + specifiers in the descriptor, described in `tor-spec.txt` + section 5.1.2. These checks SHOULD NOT leak detailed information about the client's version, configuration, or consensus. (See 3.3 for service link specifier handling.)
@@ -1903,7 +1904,7 @@ Table of contents:
The hidden service should handle invalid or unrecognised link specifiers the same way as clients do in section 2.5.2.2. In particular, services - MAY perform basic validity checks on link specifiers, and SHOULD NOT + SHOULD perform basic validity checks on link specifiers, and SHOULD NOT reject unrecognised link specifiers, to avoid information leaks.
The ONION_KEY_TYPE field is: diff --git a/tor-spec.txt b/tor-spec.txt index 34a3b44..8f30624 100644 --- a/tor-spec.txt +++ b/tor-spec.txt @@ -1128,7 +1128,9 @@ see tor-design.pdf. be listed.
Nodes MUST ignore unrecognized specifiers, and MUST accept multiple - instances of specifiers other than 'legacy identity'. + instances of specifiers other than 'legacy identity' and + 'Ed25519 identity'. (Nodes SHOULD reject link specifier lists + that include multiple instances of either one of those specifiers.)
For purposes of indistinguishability, implementations SHOULD send these link specifiers, if using them, in this order: [00], [02], [03], @@ -1154,7 +1156,7 @@ see tor-design.pdf. target OR did not prove its ownership of any such identity key. If only one identity key is provided, but the extending OR knows the other (from directory information), then the OR SHOULD also - enforce that key. + enforce the key in the directory.
If an extending OR has a channel with a given Ed25519 ID and RSA identity, and receives a request for that Ed25519 ID and a