# Policy-Gated SSH Signing (design)

Date: 2026-06-17  
Status: **design only** — not implemented in WARDEN-WP-0006

Today `warden sign` authorizes via **inventory allow-list** and TTL policy only.
This document proposes flex-auth integration so SSH issuance matches the
NetKingdom authorization path before OpenBao/SSH engine signing.

---

## Problem

Inventory-only gating is sufficient for early ops but weak for:

- many agents and automations across tenants
- temporary elevation without inventory edits
- unified audit with flex-auth decision envelopes
- aligning SSH issuance with IAM Profile claims

---

## Target flow (v2)

```text
warden sign <actor> --pubkey <path>
        |
        v
Load actor from inventory (type, principals, ttl)
        |
        v
Obtain identity claims (optional v2.1)
  OIDC token / env-injected JWT from key-cape session
        |
        v
flex-auth Evaluate
  resource: ssh-certificate / actor:<name>
  action: sign
  context: tenant, principal list, pubkey fingerprint, requestor
        |
        +-- DENY -> CAError with flex-auth explanation
        |
        v ALLOW
CABackend.sign()  (local or OpenBao SSH engine)
        |
        v
Append signatures.log (+ optional flex-auth audit correlation id)
```

---

## flex-auth request shape (proposed)

| Field | Source |
| --- | --- |
| `subject` | IAM Profile `sub` or service identity |
| `tenant` | `tenant:platform` or `tenant:coulomb` |
| `resource` | `ssh-cert:actor/<actor-name>` |
| `action` | `sign` |
| `context.principals` | From inventory |
| `context.actor_type` | adm \| agt \| atm |
| `context.pubkey_fingerprint` | SHA256 of pubkey |
| `context.ttl_hours` | Requested TTL |

Decision envelope should return `allow` \| `deny` and `audit_correlation_id`
stored in `signatures.log`.

---

## Versioning

| Version | Gate | Notes |
| --- | --- | --- |
| **v1 (today)** | Inventory + TTL max | Shipped |
| **v2** | flex-auth required for `backend: vault` production | Config flag |
| **v2.1** | Identity claims required for `adm` signs | OIDC from key-cape |
| **v3** | Tenant-scoped policies per `tenant:*` | NK recursive rule |

---

## Configuration sketch (future)

```yaml
# warden.yaml — not implemented
policy:
  enabled: true
  flex_auth_url: http://flex-auth.flex-auth.svc.cluster.local:8080
  require_identity_for_adm: true
  fail_closed: true
```

`fail_closed: true` — if flex-auth unreachable, deny sign (no silent bypass).

---

## What stays in inventory (v2)

- Actor registration (name, type, default principals, default TTL)
- Host reference documentation
- Scorecard local checks

flex-auth decides **whether this sign request is allowed now**; inventory
defines **what the actor is allowed to request**.

---

## Non-goals (this design)

- flex-auth implementation changes in WP-0006
- Replacing OpenBao SSH engine with flex-auth
- Storing flex-auth policies in ops-warden repo

---

## Implementation follow-up

Promote to **WARDEN-WP-0007** (proposed) after:

1. flex-auth resource type for `ssh-certificate` agreed
2. NK platform policy for platform vs tenant sign paths
3. Operator approval for `fail_closed` production behavior

---

## See also

- `flex-auth/INTENT.md`
- `wiki/CredentialRouting.md`
- `net-kingdom/docs/platform-identity-security-architecture.md`