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fix(ssh): make PublicKey equality match OpenSSH sshkey_equal - #43
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🔵 Needs a closer look
The new signature comparison can panic on valid caller-controlled input and needs a non-panicking implementation.
Review effort: Balanced
Findings: None
What changed in this PR
Fixes public-key comparisons so differing comments do not cause false mismatches.
Changes:
- Compares encoded keys during signature and private-key validation.
- Adds regression tests for commented and mismatched keys.
| File | Review |
|---|---|
tests/signature.rs |
Adds public-key verification regression coverage. |
src/ssh/signature.rs |
Uses encoded-key comparison, but introduces a moderate panic path for caller-constructed security keys. |
src/ssh/privkey.rs |
Uses encoded-key comparison; nit: add coverage for RSA algorithm aliases. |
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encode() panics on sk keys built without an application, and would make such keys equal to keys with an empty application. Comparing the plain key type and key data still ignores the comment, without either issue.
Compare the plain key type, cert-ness and key data, ignoring the comment and RSA signature algorithm names (rsa-sha2-256/512), which share the ssh-rsa key format per RFC 8332. Replaces PublicKey::equal_public, so both call sites go back to using ==.
timweri
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Sep 24, 2026
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This is a bug flagged by Opus 5.5.
PublicKeyderivedPartialEqover all of its fields, so the same key with a differentcomment(orssh-rsavsrsa-sha2-512label) fails the equal check. Signature verification failed when the key has a comment.The fix is a manual
PartialEqthat compareskey_type.plain,key_type.is_certandkind, matching OpenSSH'ssshkey_equal.BREAKING CHANGE:
==onPublicKeynow ignores comments.Evidence
struct sshkeyhas no comment field (sshkey.h), and sshd(8) says the comment "is not used for anything" (sshd.8).rsa-sha2-256/rsa-sha2-512"reuse the "ssh-rsa" public key format" (RFC 8332). OpenSSH maps all three toKEY_RSA(ssh-rsa.c).sshkey_equalrequires the same type (cert != plain), then compares key material (sshkey.c). OpenSSH uses it for the private-key envelope check (sshkey.c) and sshsig signer matching (sshsig.c).