Bitcoin Identity

# HODLXXI Bitcoin Identity

Overview

Use this skill to integrate HODLXXI (Universal Bitcoin Identity Layer) for agent authentication, LNURL-Auth linking, and JWT-based identity claims.

Installation

1. Fetch the skill file from the repository (raw link works for installable agents):

```bash curl -L -o SKILL.md \ https://raw.githubusercontent.com/hodlxxi/Universal-Bitcoin-Identity-Layer/main/skills/public/hodlxxi-bitcoin-identity/SKILL.md ```

1. Install helper dependencies for local verification scripts:

```bash python -m pip install ecdsa pyjwt requests ```

Quick start

1. Set a base URL for the HODLXXI deployment.
2. Register an OAuth client to obtain `client_id` and `client_secret`.
3. Run the OAuth2/OIDC authorization code flow (PKCE recommended).
4. Start an LNURL-Auth session for Lightning wallet login.
5. Verify JWTs with the JWKS endpoint.

Usage steps

1) Configure the base URL

Set the base URL to the HODLXXI deployment (update as needed):

```bash BASE_URL="https://hodlxxi.com" ```

2) Register an OAuth client

Register a client to get credentials:

```bash curl -X POST "$BASE_URL/oauth/register" \ -H "Content-Type: application/json" \ -d '{"client_name": "YourAgentName", "redirect_uris": ["https://your-callback-url"], "scopes": ["openid", "profile"]}' ```

Store `client_id` and `client_secret` securely.

3) Run OAuth2/OIDC authorization code flow

Discover endpoints:

```bash curl "$BASE_URL/.well-known/openid-configuration" ```

Create an authorization request (PKCE recommended):

```bash curl "$BASE_URL/oauth/authorize?client_id=your_client_id&redirect_uri=your_callback&response_type=code&scope=openid%20profile&code_challenge=your_challenge&code_challenge_method=S256" ```

Exchange the authorization code for tokens:

```bash curl -X POST "$BASE_URL/oauth/token" \ -H "Content-Type: application/x-www-form-urlencoded" \ -d "grant_type=authorization_code&code=received_code&redirect_uri=your_callback&client_id=your_client_id&code_verifier=your_verifier" ```

Expect an access token, ID token (JWT), and optional refresh token.

4) Start an LNURL-Auth session

Create a session and show the LNURL to the user:

```bash curl -X POST "$BASE_URL/api/lnurl-auth/create" \ -H "Accept: application/json" ```

Poll for completion after the user scans the LNURL with a Lightning wallet:

```bash curl "$BASE_URL/api/lnurl-auth/check/your_session_id" ```

5) Verify JWTs

Fetch JWKS:

```bash curl "$BASE_URL/oauth/jwks.json" ```

Verify with Python (example uses PyJWT):

```python import jwt import requests

jwks = requests.get("https://your-hodlxxi-deployment.com/oauth/jwks.json", timeout=10).json() public_key = jwt.algorithms.RSAAlgorithm.from_jwk(jwks["keys"][0]) claims = jwt.decode(your_jwt, public_key, algorithms=["RS256"], audience="your_audience") print(claims) ```

6) Monitor health and metrics

Check liveness and OAuth system status endpoints:

```bash curl "$BASE_URL/health" curl "$BASE_URL/oauthx/status" ```

Code examples

Register a client from a JSON template

```bash curl -X POST "$BASE_URL/oauth/register" \ -H "Content-Type: application/json" \ -d @templates/oauth-client.json ```

Create LNURL session and poll

```bash session_json=$(curl -s -X POST "$BASE_URL/api/lnurl-auth/create") session_id=$(python3 -c 'import json,sys; print(json.loads(sys.argv[1])["session_id"])' "$session_json") curl "$BASE_URL/api/lnurl-auth/check/$session_id" ```

Best practices

• Always use HTTPS and verify TLS certificates in production.
• Keep client secrets in a secrets manager or environment variables.
• Use PKCE for public clients and rotate secrets for confidential clients.
• Treat LNURL sessions as single-use and enforce short TTLs.
• Validate `aud`, `iss`, and `exp` claims for JWTs.

Advanced features

• Use `/oauthx/docs` for live OAuth/OIDC API documentation.
• Use `/oauthx/status` to monitor database and LNURL session health.
• Rotate JWKS keys via the server configuration (JWKS directory + rotation days).

PAYG billing for OAuth clients

Paid API calls are billed per OAuth `client_id` (agent/app), not per session pubkey. When balance or free quota is exhausted, paid endpoints return HTTP 402 with a Lightning top-up path.

Billing endpoints (OAuth token required)

• `POST /api/billing/agent/create-invoice`
• `POST /api/billing/agent/check-invoice`

Example create invoice:

```bash curl -X POST "$BASE_URL/api/billing/agent/create-invoice" \ -H "Authorization: Bearer $ACCESS_TOKEN" \ -H "Content-Type: application/json" \ -d '{"amount_sats": 1000}' ```

Example check invoice:

```bash curl -X POST "$BASE_URL/api/billing/agent/check-invoice" \ -H "Authorization: Bearer $ACCESS_TOKEN" \ -H "Content-Type: application/json" \ -d '{"invoice_id": "your_invoice_id"}' ```

402 response shape

When a paid endpoint is called with insufficient balance, expect:

```json { "ok": false, "error": "payment_required", "code": "PAYMENT_REQUIRED", "client_id": "your_client_id", "cost_sats": 1, "balance_sats": 0, "create_invoice_endpoint": "/api/billing/agent/create-invoice", "hint": "Top up via Lightning PAYG" } ```

Supporting files

• `scripts/verify_signature.py` validates LNURL-Auth signatures locally.
• `HEARTBEAT.md` describes periodic health checks for the deployment.
• `templates/oauth-client.json` provides a ready client registration payload.

Optional helper script

Use `scripts/verify_signature.py` to validate LNURL signatures locally. Install the dependency first:

```bash python -m pip install ecdsa python scripts/verify_signature.py --k1 <hex> --signature <hex> --pubkey <hex> ```