95d1ff833c
Adds a "Configuration env vars" section listing every RELICARIO_* variable read by production code, with purpose and trust boundary. Splits user-facing vars from debug-only ones (cfg(debug_assertions)) to make the attack surface explicit for security reviewers. Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
93 lines
3.9 KiB
Markdown
93 lines
3.9 KiB
Markdown
# Relicario Security Model
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## Cryptographic Protection
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Relicario uses two-factor vault decryption:
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1. **Passphrase** — user-memorized, zxcvbn score ≥3 required
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2. **Reference image** — JPEG carrying 256-bit secret via DCT steganography
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Key derivation: Argon2id (64 MiB memory, 3 iterations, 4 parallelism)
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Encryption: XChaCha20-Poly1305 (192-bit nonce, 256-bit key)
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## Manifest Integrity
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The manifest (`manifest.enc`) is encrypted with AEAD, which provides:
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- **Confidentiality**: Contents unreadable without master key
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- **Integrity**: Any modification detected and rejected on decrypt
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- **Authenticity**: Only master key holders can create valid ciphertexts
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### What AEAD Does NOT Protect
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- **Item deletion**: An attacker with write access can delete `.enc` files
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or git-revert commits. The manifest decrypts successfully but won't
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contain the deleted items.
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- **Rollback attacks**: An attacker can replace `manifest.enc` with an
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older valid version. AEAD accepts any ciphertext created with the key.
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### Mitigation
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Item deletion and rollback are detectable via **git history**:
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```bash
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git log --oneline items/
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```
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For environments where git history could be rewritten (force-push):
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1. Enable device authentication (commit signing + pre-receive hook)
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2. Use a git server that rejects non-fast-forward pushes
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3. Regular backups with `relicario backup export`
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## Device Authentication
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When enabled, device authentication provides:
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- **Commit authorship**: All commits signed by registered device keys
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- **Push access control**: Deploy keys managed via Gitea API
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- **Instant revocation**: One command cuts off both signing and push
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See `docs/superpowers/specs/2026-05-02-device-authentication-design.md`.
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## Access Control
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Without device authentication, access control is transport-layer only:
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- **CLI**: SSH key authentication to git remote
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- **Extension**: Git credentials in browser storage
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Device registration was optional before v0.4.0. With device auth enabled,
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all commits must be signed by a registered device.
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## Configuration env vars
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Relicario reads the following environment variables. Each is a trust
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boundary: an attacker who can set them in the user's environment can
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influence Relicario's behavior. They are listed here for security
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reviewers to audit the surface in one place.
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### User-facing (active in all builds)
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| Variable | Purpose | Trust |
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|---|---|---|
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| `RELICARIO_IMAGE` | Override the reference-image JPEG path used during vault unlock. | Trusted: filesystem path under the user's control. Read-only; its bytes feed `imgsecret::extract_secret`. |
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| `RELICARIO_GITEA_URL` | Gitea API base URL for `relicario device add`. Equivalent to `--gitea-url`. | Trusted: HTTPS URL. Used only in the device-add code path. |
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| `RELICARIO_GITEA_TOKEN` | Gitea personal-access token. Equivalent to `--gitea-token`. | **Secret**: anyone who can read this env var can manage the user's deploy keys via the Gitea API. The CLI never logs it. |
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| `RELICARIO_GITEA_OWNER` | Gitea repository owner (e.g. `alee`). Equivalent to `--owner`. | Trusted: opaque string. |
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| `RELICARIO_GITEA_REPO` | Gitea repository name (e.g. `vault`). Equivalent to `--repo`. | Trusted: opaque string. |
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### Debug-only (compiled out of `cargo build --release`)
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The following variables are gated behind `cfg(debug_assertions)` and
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are **no-ops** in release builds. The env-var lookup is removed by the
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optimiser from any binary built without debug assertions (i.e. the
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standard `--release` profile).
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| Variable | Purpose |
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|---|---|
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| `RELICARIO_NO_GROUPS_CACHE` | Suppress the plaintext `groups.cache` write. Developer debugging tool for the cache logic. |
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| `RELICARIO_TEST_PASSPHRASE` | Bypass the `rpassword` prompt during integration tests. |
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| `RELICARIO_TEST_ITEM_SECRET` | Bypass the `rpassword` prompt for item-secret fields during integration tests. |
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| `RELICARIO_TEST_BACKUP_PASSPHRASE` | Bypass the `rpassword` prompt for backup export/restore passphrases during integration tests. |
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