# MVG Air‑gapped Verifier Kit — Key Rotation & Keyring Policy (Public‑safe)

**Version:** v1.0.0  
**Issued (UTC):** 2026-02-12T04:00:00Z  
**Scope:** Offline verification of MVG air‑gapped verifier kit supply‑chain artifacts.

> Boundary language (procurement‑grade): This document is informational only and **non‑binding unless signed**.
> Public materials do **not** grant any patent license by publication. This is **not** a compliance certification.

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## 1) Goals

1. **Rotation without breaking verification**  
   Reviewers must be able to validate historical artifacts even after signing keys rotate.

2. **Fail‑closed behavior**  
   Missing/unsupported crypto yields **HOLD**. Cryptographic or integrity mismatches yield **FAIL**.

3. **Offline‑first**  
   Verification is designed to be performed with no network access.

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## 2) Objects

### 2.1 Trust anchors (root)
File: `MVG_Airgapped_Verifier_Kit_Keyring_TrustAnchors_PUBLIC_v1.0.0.json`  
A small set of pinned public keys that can verify a **signed keyring snapshot**.

### 2.2 Signed keyring snapshot (DSSE)
File: `MVG_Airgapped_Verifier_Kit_Keyring_PUBLIC_v1.0.0.dsse.json`  
Payload type: `application/vnd.mvg.airgapped_verifier_kit.keyring_snapshot+json`  
Contains the list of currently recognized signing keys, their roles, and lifecycle metadata.

### 2.3 Signing keys (in keyring)
Keys are scoped by **role**, for example:

- `airgap_kit.release.dsse.sign` — kit release receipts
- `airgap_kit.commitments.dsse.sign` — commitment log heads + private receipts
- `airgap_kit.headchain.dsse.sign` — commitment headchain heads (log‑of‑heads)

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## 3) Lifecycle states

Each key has a `status`:

- **active** — valid for signing new artifacts
- **deprecated** — valid for verification within a grace window
- **revoked** — MUST NOT be accepted for verification (FAIL)

Recommended evaluator behavior:

- `active` → accept
- `deprecated` and `now ≤ grace_until_utc` → accept (mark as deprecated)
- `deprecated` and `now > grace_until_utc` → **HOLD** (unless an explicit legacy override is enabled)
- `revoked` → **FAIL**

> Why HOLD after grace? Offline machines can have inaccurate clocks. HOLD is fail‑closed without creating false accusations.

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## 4) Rotation procedure (public‑safe)

1. MVG issues a new signing key (new `kid`) for the relevant role.
2. MVG publishes an updated **signed keyring snapshot** (DSSE), verified by the pinned trust anchor(s).
3. MVG marks the previous key as `deprecated` and sets `grace_until_utc`.
4. After the grace window, MVG may mark the old key as `revoked` (or keep it deprecated for historical verification under agreement).

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## 5) Audit attachment set (recommended)

For a procurement/audit record, the recommended attachment set is:

- Artifact ZIP (kit or pack)
- Artifact DSSE receipt
- Signed keyring snapshot DSSE (the snapshot used for verification)
- Any referenced logs/heads (if applicable)
- Verifier print summary (PASS/FAIL/HOLD) with Approval ID / QR re‑verification

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## 6) Non‑binding boundary language

- **Non‑binding unless signed.** Binding terms exist only in fully executed agreements.
- **No patent license by publication.** Public materials are informational only.
- **Not a certification.** This is a verification format + toolchain, not a compliance stamp.