Elamur Groupantsmova-serve-auth
The groupant beside tools/mova-serve/src/auth.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| Approximant | partial | Approximant |
| Ast | partial | syntax.json |
| Cost | symbolic source derived | Cost |
| Descriptant | present | Descriptant |
| Invariant | partial | Invariant |
| Tests | executed bounded checks | Tests |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| relation | type | label | where |
|---|---|---|---|
| Behavior complement | behavior complement | partial source derived model | Behavior complement |
| Reverse reconstruction | reverse reconstruction | partial source derived model | Reverse reconstruction |
| Model presence | model presence | partial source derived model | Model presence |
Model text
Descriptant
Accounts: OpenID Connect authorization code flow with PKCE (S256) against Google; the ID token's RS256 signature checked against the JWKS with iss, aud, exp, nonce and a verified e-mail; sessions and API keys as SHA-256 hashes; the terms version and time of every acceptance; CSRF tokens as HMAC of the session.
Approximant
begin → (state, nonce, verifier); callback(code, state) = verify(exchange(code, verifier), jwks, aud, nonce) → sign_in; by_key(k) = account(hash(k)) if key.terms = current.
Invariant
No session token or key is stored in clear; a pending login is used once and expires in ten minutes; keys and sessions of outdated terms do not authenticate; deletion removes the account, its keys and its sessions.
Cost
Two HTTPS calls a sign-in (token, JWKS when expired); O(log n) lookups.
Behavior complement
No password, no e-mail sending, no OAuth server of its own (MCP uses API keys, not OAuth 2.1).
Reverse reconstruction
A key's prefix and hash identify it; the acceptance records recover who accepted which terms when.
Model presence
Without the settings file there are no accounts.
Tests
auth::tests: a token signed by a test key verifies, and each of audience, nonce, expiry, issuer, a changed claim,
an unknown key and an unverified e-mail is refused; PKCE equals RFC 7636 appendix B; accounts, sessions and keys
survive a restart as hashes, outdated terms refused, revoke and delete; CSRF bound to the session.
Provenance
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/tools/mova-serve/src/auth.rs.groupant/