Stage 1b. Still no enforcement wired — this adds the credential model the
identity cutover (stage 2) will read.
ApiKey holds one principal per key, deliberately. The reason to separate keys
from principals is so many keys share a grant set and rotating a key never
touches an ACL row, and that holds with one principal per key since nothing stops
two keys naming the same principal. A key belonging to several principals at once
buys little and costs a join table. UserAuthorizationState.Principals stays a
list, so adding it later needs no ACL-side change.
ApiKeySecret is the security-critical half and is pure, so it is tested on its
own: otua_<keyId>_<secret>, peppered HMAC-SHA256, FixedTimeEquals. Notes why a
plain HMAC rather than an iterated KDF (the secret is 32 bytes of CSPRNG, and the
call runs inline on session activation, which the SDK serializes server-wide
behind its SessionManager event lock), and fails closed on an unset pepper rather
than hashing under an empty key.
Found and fixed a bug in my own first draft: the key id was url-safe base64,
whose alphabet maps '/' to '_' — the very character TryParse splits on. Roughly
one key in five would have had its id truncated at a random position, an
intermittent auth failure reproducing only for SOME keys. The id is hex now, and
the guard is falsified: reverting the alphabet reds both
The_generated_key_id_never_contains_the_separator and, as a bonus signal,
Two_generated_keys_never_collide, because truncated ids collide.
ApiKeyId is NOT NULL, unlike the nullable NodeAclId precedent whose filtered
unique index would admit two NULL ids. Fine for a config row, not for a
credentials lookup key.
OpcUaServer.csproj now references Core. Until now it did not, so
IPermissionEvaluator was literally uncallable from the node manager — the place
enforcement has to happen. No new transitive package surface.
Schema doc updated for both, and its NodeAcl block flagged for pre-existing drift
(it still documents the GenerationId column v3 dropped) without fixing it here.
Core 247, OpcUaServer 364, Configuration 128 — all green.
Claude-Session: https://claude.ai/code/session_015p7wGqy3YpZNCpDzTpGMKo
Joseph Doherty
f88eb49bd1