archy/docs/adr/002-did-key-method.md

# ADR-002: DID Key Method for Node Identity

**Status**: Accepted
**Date**: 2026-03

## Context

Each Archipelago node needs a cryptographic identity for peer authentication, federation, and verifiable credentials. Multiple DID methods exist (did:web, did:ion, did:key, did:peer).

## Decision

Use `did:key` as the primary DID method.

## Consequences

### Positive
- **Self-contained**: The DID document is derived entirely from the public key — no external resolution needed
- **Offline-capable**: Works without internet, aligning with sovereignty principles
- **Simple**: No registration, no blockchain, no web server required
- **Fast**: DID resolution is a local computation, not a network request
- **Ed25519**: Uses Ed25519 keys which are fast, compact, and well-supported

### Negative
- **No key rotation**: The DID is bound to a single key; rotating requires a new DID
- **No service endpoints in DID**: Cannot embed service URLs in the DID document itself
- **No revocation**: Cannot revoke a did:key without out-of-band mechanisms

### Mitigation
- Use federation trust lists for key management and revocation
- Store service endpoints (onion address, pubkey) separately in federation state
- Support migration to did:peer or did:web in future versions if key rotation is needed
release(v1.7.41-alpha): post-OTA auto-rollback so a bad release cannot strand the fleet Closes failure mode FM5 from docs/bulletproof-containers.md: the v1.7.38 + v1.7.39 rollouts left every affected node on an unreachable UI (nginx 500) with no recovery path short of SSH. This release adds a self-check guardrail to the update flow. What changed: - apply_update() writes a pending-verify marker with old+new version and a 150s deadline immediately before scheduling the service restart. - verify_pending_update() runs from main.rs startup. If the marker is present and within its freshness window, the new binary waits 15s for nginx + backend to settle, then probes https://127.0.0.1/ every 5s for up to 90s (self-signed certs accepted). - On any probe success within the window, the marker is cleared and nothing else happens. - On window-exhaust, the new binary: 1. Moves the broken /opt/archipelago/web-ui to web-ui.failed.<ts> (quarantined, not deleted, so we can post-mortem). 2. Restores web-ui.bak on top of web-ui. 3. Calls rollback_update() to restore the previous binary. 4. Updates state.current_version to reflect the rollback. 5. systemctl --no-block restart archipelago so the OLD binary boots. - Markers older than 10 minutes are treated as stale and cleared without probing, so a crashed-during-startup marker from weeks ago cannot spontaneously roll back a healthy node on a later reboot. - rollback_update() binary copy now goes through host_sudo instead of tokio::fs::copy, so it escapes the service's ProtectSystem=strict mount namespace. Without this, the rollback silently failed with EROFS on /usr/local/bin and orphaned the rollback - the exact opposite of what auto-rollback is for. Tests: 4 new unit tests in update::tests covering marker round-trip, absent-marker noop, no-panic on verify_pending_update with nothing to verify, and an invariant assert that the 90s probe window stays below the 600s stale threshold. All passing. Side fix: scripts/create-release-manifest.sh was dying with exit 141 (SIGPIPE from tar tvzf pipe head pipe awk) under set -euo pipefail. Replaced with a single awk NR==1 that doesn't short-circuit the upstream pipe, so the release-build flow is idempotent again. 2026-04-22 16:14:35 -04:00			`# ADR-002: DID Key Method for Node Identity`

			`Status: Accepted`
			`Date: 2026-03`

			`## Context`

			`Each Archipelago node needs a cryptographic identity for peer authentication, federation, and verifiable credentials. Multiple DID methods exist (did:web, did:ion, did:key, did:peer).`

			`## Decision`

			Use `did:key` as the primary DID method.

			`## Consequences`

			`### Positive`
			`- Self-contained: The DID document is derived entirely from the public key — no external resolution needed`
			`- Offline-capable: Works without internet, aligning with sovereignty principles`
			`- Simple: No registration, no blockchain, no web server required`
			`- Fast: DID resolution is a local computation, not a network request`
			`- Ed25519: Uses Ed25519 keys which are fast, compact, and well-supported`

			`### Negative`
			`- No key rotation: The DID is bound to a single key; rotating requires a new DID`
			`- No service endpoints in DID: Cannot embed service URLs in the DID document itself`
			`- No revocation: Cannot revoke a did:key without out-of-band mechanisms`

			`### Mitigation`
			`- Use federation trust lists for key management and revocation`
			`- Store service endpoints (onion address, pubkey) separately in federation state`
			`- Support migration to did:peer or did:web in future versions if key rotation is needed`