vaid-mint (Python)

The Python mirror of the Rust vaid-mint crate: the open, self-hostable reference mint for the VAID (Verifiable Agent Identity) standard.

• mint_root — mint a root/operator VAID (BYO-key with proof-of-possession, or generate-and-discard), gated by an explicit AuthorizationGate.
• mint_child — attenuated delegation: an authenticated parent mints a child whose authority is always a subset of its own (child ⊆ parent).

Trust model — read this before using the mint

Upgrading from 0.1.1? Expiry enforcement is a ⚠️ breaking behavioral change despite the patch version bump: verify_vaid now returns False for expired VAIDs that previously passed. Read CHANGELOG.md before upgrading. Note that 0.1.2 is not yet on PyPI — pip install vaid-mint still serves 0.1.1, which has neither the seam nor expiry enforcement described below.

Revocation now has a pluggable seam, but the shipped default is still non-durable. As of 0.1.2 there is a RevocationCheck protocol: a self-hoster can inject their own durable, restart-surviving backend via ReferenceIssuer.with_revocation_check without patching the package. What ships by default, however, is still the concrete in-memory revoked set — it does not survive a restart. If the mint process restarts and you have not wired a durable RevocationCheck, previously revoked VAIDs are revocable again. The seam closes the "no extension point" gap; it does not by itself make revocation durable. That is your responsibility to wire, or the hosted authority's to provide.

from vaid_mint import InMemoryRevocationList, ReferenceIssuer

class MyDurableRevocations:
    """Your own restart-surviving store (or a refreshed snapshot of one)."""
    def is_revoked(self, vaid_id: str) -> bool:
        return vaid_id in load_deny_list()

# The injected check is consulted IN ADDITION TO the built-in in-memory set —
# a VAID is rejected if EITHER reports it revoked.
issuer = ReferenceIssuer.ephemeral(1).with_revocation_check(MyDurableRevocations())

# Or wire the seam with the shipped in-memory list before a durable backend exists:
revocations = InMemoryRevocationList()
issuer = ReferenceIssuer.ephemeral(1).with_revocation_check(revocations)
revocations.revoke(vaid["vaid_id"])
assert not issuer.verify_vaid(vaid)

If you're running this in production, mitigate as follows:

• Mint short-lived VAIDs. vaid_ttl_hours controls issuance TTL, and DEFAULT_VAID_TTL_HOURS (1h) is the recommended baseline. Expiry is now enforced at verification — an expired VAID hard-fails verify_vaid, not merely reported — so a short TTL is a real backstop that shrinks the exposure window for a leaked or compromised VAID even without durable revocation. Treat TTL as your primary control today.
• Inject a durable RevocationCheck (e.g. backed by a shared store or a periodically-refreshed snapshot of one) if you need revocation to survive restarts. The injected check is consulted in addition to the built-in in-memory set, so enabling it never disables existing behavior.
• Or front the mint with a revocation-aware proxy or allowlist — e.g. a sidecar or gateway that checks a durable deny-list before forwarding to verify_vaid.
• Do not rely on the default configuration alone for revocation guarantees that must survive a process restart.

The RevocationCheck seam mirrors the injection style of AuthorizationGate and AuditSink, with one deliberate difference: its default is not an honest no-op. For revocation, a no-op default would mean nothing is ever checked — a silent functional regression, not a neutral "not wired yet" state — so the reference keeps its working in-memory set as the default. A NeverRevoked no-op is available as an explicit opt-in. The hosted product additionally offers a durable, hash-chained revocation store; the open package now gives you the seam to plug your own into.

Unguarded defaults: authorization and delegation

This is a reference implementation with two deliberate, unguarded defaults:

1. mint_root has no authorization gate by default (PermitAll). Anyone who can call this code can mint a root VAID. Supply a real AuthorizationGate for anything beyond local experimentation.
2. mint_child is intentionally ungated — attenuation is the authorization. Any holder of a valid parent VAID can mint children from it; a child can only narrow scope/capabilities relative to its parent, never widen (child ⊆ parent). Possession of a parent VAID is itself the authorization boundary for delegation here. Treat parent-VAID custody with the same care as a credential.

Neither of these is a security recommendation for production use — they are the honest defaults of a self-hostable reference mint. See the sections below for where each is enforced in code.

from vaid_mint import ReferenceIssuer, InMemoryAudit, MintService, VaidSeed

issuer = ReferenceIssuer.ephemeral(24)
mint = MintService(issuer, InMemoryAudit())
root = mint.mint_root(VaidSeed(
    agent_class="orchestrator", version="1.0.0", tenant_id="acme",
    scope_boundary=["data.acme"], capability_set=["read", "write"],
))
assert issuer.verify_vaid(root)

The split

This is the open engine of a HashiCorp-Vault-style split. KMS-backed kernel keys and the audit-of-record are the closed managed authority and are not here. Revocation is the seam worth naming plainly rather than filing under "commercial": as of 0.1.2 this package ships a pluggable RevocationCheck seam — additive, with a non-durable in-memory default — and VAID expiry (TTL) is hard-enforced at verification. What stays commercial is durable revocation itself: a restart-surviving, hash-chained store. The package ships the seam, not the durability.

mint_root is gated by an AuthorizationGate that defaults to PermitAll — a reference-implementation choice, not a security recommendation; production deployments should pass a real gate to MintService.

mint_child is intentionally ungated because attenuation is the authorization: any holder of a valid parent VAID can mint children from it, and a child can only narrow scope/capabilities relative to that parent, never widen (child ⊆ parent). So possession of a parent VAID is itself the authorization boundary for delegation — treat parent-VAID custody with the same care as a credential.

Cross-language byte-identity

Proof-of-possession reuses the vaid-pop primitive verbatim. The signed VAID document is proven byte-identical to the Rust mint by the vendored frozen vector vaid_mint/vectors/mint_v1.json (the same mint_v1.json the Rust mint_conformance test asserts). Run the packaged firewall:

vaid-mint-conformance          # exit 0 = PASS (installed mint == frozen vector)

Per Decision B this is self-consistent within this repo (Rust == Python); it is not byte-conformant against the managed authority's (still-moving) VAID format.

Install (local dev)

vaid-mint depends on vaid-pop. For a local checkout, install both editable:

pip install -e python/vaid-pop
pip install -e python/vaid-mint --no-deps