<p align="center">
  <img src="extension/icons/relicario-logo.svg" alt="Relicario" width="128" height="128">
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# Relicario

> **Audience:** users + evaluators. This doc owns the pitch, security-model summary, quick-start commands, reference-image explanation, recovery-QR overview, and roadmap teaser. Goes no deeper — for the system tour see [DESIGN.md](DESIGN.md), for crypto see [docs/CRYPTO.md](docs/CRYPTO.md).

A git-backed, self-hostable password manager where decryption requires two independent factors: a passphrase you memorize and a reference JPEG that carries a hidden secret. Compromise of either factor alone is insufficient.

The server only ever sees opaque ciphertext. There is nothing else going on. This README is the security proof.

## How it works

```
Your passphrase (something you know)
        +
Your reference photo (something you have)
        |
        v
   [ Argon2id KDF ]  -->  master_key  -->  [ XChaCha20-Poly1305 ]  -->  encrypted vault
        ^                                                                      |
        |                                                                      v
   Never leaves                                                          Stored in git
   your device                                                         (opaque ciphertext)
```

At vault creation, Relicario embeds a random 256-bit secret into a carrier JPEG using DCT steganography. This photo becomes your **reference image** — a second factor that lives on your devices (and optionally as a "dead drop" on social media, since it survives JPEG re-encoding and mild cropping).

To unlock the vault, you provide your passphrase and point the client at the reference image. The client extracts the hidden secret, concatenates it with your passphrase, and runs Argon2id to derive the master key. Everything else follows from there.

## Security model

### What the server sees

A git repository containing:
- `manifest.enc` — opaque binary blob
- `items/*.enc` — more opaque binary blobs
- `attachments/<item-id>/*.enc` — encrypted attachment blobs
- `settings.enc` — encrypted vault settings
- `.relicario/salt` — a random 32-byte value (not secret)
- `.relicario/params.json` — Argon2id parameters (not secret)
- `.relicario/devices.json` — authorized device public keys

That's it. No plaintext. No metadata about what's inside. No keys, no passphrases, no reference images.

### What an attacker needs

| Scenario | Has | Needs | Result |
|---|---|---|---|
| Server breach | Encrypted vault + salt | Passphrase AND image secret | 256+ bits of entropy. Infeasible. |
| Server breach + stolen image | Vault + image secret | Passphrase | Passphrase entropy through Argon2id. 4 diceware words = ~7 million years. |
| Shoulder-surfed passphrase | Passphrase | Image secret | 256 bits. Infeasible. |
| Stolen device | Image + vault | Passphrase | Argon2id brute-force. Strong passphrase = safe. |

No single point of failure. The two-factor design means the passphrase alone can't decrypt the vault, and the image alone can't decrypt the vault.

### Compared to

| | Server breach entropy | KDF factors |
|---|---|---|
| LastPass | ~40-60 bits (master password only) | 1 |
| Bitwarden | ~40-60 bits (master password only) | 1 |
| 1Password | password + 128-bit Secret Key | 2 |
| **Relicario** | **password + 256-bit image secret** | **2** |

### What we don't protect against

- A compromised device with active malware. No software password manager can.
- Weak passphrases with a stolen reference image. Use 4+ diceware words.
- Rubber-hose cryptanalysis.

## Quick start

```bash
# Build from source
cargo build --release

# Create a vault (pick any JPEG as the carrier)
relicario init --image vacation.jpg --output reference.jpg

# Add a credential
relicario add

# Retrieve it
relicario get github

# List everything
relicario list

# Sync with your git remote
relicario sync

# Pack the vault into a single encrypted backup file
relicario backup export -o vault.relbak

# Print a recovery QR for your image_secret (see "Recovery" below)
relicario recovery-qr generate

# Generate a random password
relicario generate -l 32
```

### Environment variable

Set `RELICARIO_IMAGE=/path/to/reference.jpg` to avoid being prompted for the image path on every command.

## The reference image

The reference JPEG is generated once during `relicario init`. It looks like a normal photo — because it is one. The 256-bit secret is embedded in the DCT coefficients of the luminance channel using Quantization Index Modulation, with heavy redundancy and Reed-Solomon-style majority voting across multiple copies.

The embedding survives:
- JPEG recompression (tested down to quality 85)
- Up to ~10-15% cropping from any edge
- Social media re-encoding (Instagram, Discord, etc.)

This means your reference image can live on your Instagram, your personal website, or anywhere else. It's useless without your passphrase.

## Recovery: what if I lose my reference image?

Without your reference image, the vault is undecryptable — that's the security model. But it also makes a lost or corrupted image a single point of failure.

The mitigation is the **recovery QR**: a printable QR code that wraps your image secret behind a separate recovery passphrase you choose. If you ever lose access to the reference JPEG, scan or transcribe the QR, provide the recovery passphrase, and recover the 256-bit image secret. Combined with your normal vault passphrase, this restores access to the vault.

```bash
# Print a recovery QR (after the vault is unlocked).
# You'll be prompted for a separate recovery passphrase.
relicario recovery-qr generate

# Recover the image_secret from a stored QR payload.
relicario recovery-qr unwrap
```

The QR payload is an XChaCha20-Poly1305 envelope keyed by Argon2id over a domain-separated input (prefixed with `b"relicario-recovery-v1\0"`), so even if you reuse your vault passphrase as your recovery passphrase, the wrap key cannot collide with a vault master key. Both salt and nonce are freshly randomized per call, so two QRs printed from the same passphrase yield different bytes — the printed copy doesn't leak whether you've printed others.

Recommended practice: print the QR, store it offline (safe, deposit box), and forget about it. The recovery passphrase is what protects the printed copy from being useful to someone who finds it.

## Architecture

A short tour of the four codebases and how they fit together lives in [DESIGN.md](DESIGN.md). Crypto pipeline diagrams are in [docs/CRYPTO.md](docs/CRYPTO.md); the wire format reference is [docs/FORMATS.md](docs/FORMATS.md); the threat model is [docs/SECURITY.md](docs/SECURITY.md).

`relicario-core` is the platform-agnostic bytes-in/bytes-out heart — no filesystem, no network. The CLI binary and the browser-extension WASM bridge both consume it. See per-codebase deep-dives in `crates/*/ARCHITECTURE.md` and `extension/ARCHITECTURE.md`.

### Crypto primitives

| Primitive | Purpose | Why this one |
|---|---|---|
| Argon2id (64 MiB, 3 iter, 4 parallel) | Key derivation from passphrase + image secret | Memory-hard, GPU-resistant, OWASP recommended |
| XChaCha20-Poly1305 | Authenticated encryption of vault entries | 192-bit nonce (no collision risk), fast in WASM/ARM without AES-NI |
| ed25519 | Device key signing | Per-device commit authorization, revocable without KDF rotation |

### Encrypted file format

```
version (1 byte) | nonce (24 bytes) | ciphertext (variable) | auth tag (16 bytes)
```

Every write generates a fresh random nonce. The version byte allows future format changes.

## Vault layout

```
my-vault.git/
├── manifest.enc          # Encrypted item index (names, URLs, timestamps)
├── settings.enc          # Encrypted vault settings (retention, caps, generator defaults)
├── items/
│   ├── a1b2c3d4e5f6a7b8.enc   # One encrypted item per file
│   └── …
├── attachments/
│   └── <item-id>/
│       └── <aid>.enc     # Content-addressed encrypted attachment blob
└── .relicario/
    ├── salt              # 32-byte random salt (not secret)
    ├── params.json       # KDF parameters
    ├── devices.json      # Authorized device public keys
    └── revoked.json      # Revoked device records (when device auth is enabled)
```

Item IDs are random 16-char hex strings (64 bits of entropy). Git history is preserved — every add/edit/delete is a commit. "When was this password last rotated?" is answered by `git log` and by the per-item field history.

## Device management

Each device generates its own ed25519 keypair. The public key is stored in `.relicario/devices.json` (committed to the repo). Device keys are used for commit signing — they do NOT participate in vault decryption.

Revoking a device: remove its key from `devices.json` and commit. No passphrase or reference image rotation needed.

```bash
relicario device add --name laptop
relicario device list
relicario device revoke laptop
```

## Building

Requires Rust stable (1.70+).

```bash
git clone ssh://git@git.adlee.work:2222/alee/relicario.git
cd relicario
cargo build --release
cargo test
```

The binary is at `target/release/relicario`.

## Roadmap

- [x] WASM build + Chrome MV3 browser extension (inline crypto, no native messaging)
- [x] Firefox WebExtension build
- [x] Typed items: Login, SecureNote, Identity, Card, Key, Document, TOTP
- [x] Secure document storage (encrypted file attachments)
- [x] Backup & restore (`.relbak` encrypted envelope)
- [x] Recovery QR (paper-printable image_secret backup with separate passphrase)
- [x] LastPass CSV import
- [x] Device authentication (ed25519 commit signing + pre-receive hook)
- [ ] Import from Bitwarden / 1Password
- [ ] `relicario unlock` daemon (ssh-agent-style, holds master key for a TTL)
- [ ] Android/iOS clients (Rust core compiles to ARM)
- [ ] Safari extension

## License

GPL-3.0-or-later — see [LICENSE](LICENSE).

---

Built by [Aaron D. Lee](https://adlee.work). Design spec and threat model in `docs/superpowers/specs/`.

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**Next:** [DESIGN.md](DESIGN.md) — the system tour.
