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fix(server): accept $2x$ in hash check and equalize unusable-hash timing - #357
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…le hashes reload_users warned that users with a $2x$ bcrypt hash cannot log in, although verify_internal dispatches every $2 hash to bcrypt, which accepts version 2x. Add $2x$ to is_supported_hash_format, the warning text, and the UserDefinition::password_hash docs. Dispatch is unchanged. Users whose stored hash is unusable (unsupported prefix, malformed Argon2, malformed bcrypt) returned without any hash work, unlike unknown users. Call verify_dummy_hash on those three paths so they cost the same as other failures; the malformed Argon2 case still returns the same Err and the auth provider still rejects. A cfg(test) counter on verify_dummy_hash lets tests assert this deterministically instead of by wall-clock time. Tests: cargo test --lib server::auth::password, cargo clippy --lib --tests and --lib with -D warnings, cargo fmt --check. Closes #356
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An Argon2 PHC string such as `$argon2id` or one missing the salt or hash output parses, so it passed the load-time format check with no warning, and argon2 reports PasswordInvalid for it without hashing, so it also skipped the dummy hash added for unusable hashes. Reject such hashes in `is_supported_hash_format` and return the malformed-hash error from `verify_argon2`, which routes them through the dummy-hash path. Login outcome is unchanged: these users still cannot authenticate. Found by the security review of this PR. Tests cover the three incomplete forms in the format check and the dummy-hash counter test, and both fail without the fix. Also rename the bad-version bcrypt fixture variable to match what it holds. Refs #356
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Nov 10, 2026
Bump the crate, lockfile, and manpages to 3.1.2 and add release entries to README, CHANGELOG, and debian/changelog covering #355 and #357: the load-time warning for unusable server password hashes, the dummy-hash timing fix for unusable and malformed stored hashes, and the hash format documentation.
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Follow-up to #354 / #355. Users with a
$2x$bcrypt hash can log in but triggered the load-time "cannot log in" warning, and users with an unusable stored hash returned faster than users with a real hash, which the 100 ms floor inverifyonly hides on fast hosts. Login outcomes are unchanged for every input;verify_internal's$2dispatch is untouched.is_supported_hash_format, the load-time warning text and theUserDefinition::password_hashrustdoc now list$2x$.verify_dummy_hashnow runs, matching the invalid-username and unknown-user branches, for: unsupported-format hashes (*,!, empty,$6$), malformed Argon2 hashes (the originalErris still returned, soverify_passwordstill logs it and rejects), and malformed bcrypt hashes (bad version, truncated).$argon2idor$argon2id$v=19$m=19456,t=2,p=1) are now treated as malformed:is_supported_hash_formatrejects them, so they get the load-time warning, andverify_argon2returns the malformed-hash error, so they take the dummy-hash path. Before, argon2 reported them as a wrong password without hashing anything.#[cfg(test)]call counter onPasswordVerifierlets tests assert exactly one dummy hash per unusable-hash or unknown-user attempt and none for valid users, with no wall-clock assertions. It is absent from non-test builds.Changes during review
The incomplete-Argon2 case was found by the security review and folded in here since it is the same unusable-hash timing gap #356 targets. Both tests covering it fail with the check removed.
Verification
cargo fmt --all -- --check,cargo clippy --all-targets --all-features -- -D warningsandcargo clippy --lib -- -D warningsare clean.cargo test --no-fail-fastpasses every target except the fourtests/integration_test.rstests, which fail identically on cleanmainlocally (localhost SSH sandbox) and are left to CI.Closes #356