> For the complete documentation index, see [llms.txt](https://docs.lingoql.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.lingoql.com/sub0/apis-abi/authentication.md).

# Authentication

Authentication in Sub0 has two parts:

1. issue a token with `tokenize`
2. protect later endpoints with `protected`

### Issue a token

Use `tokenize` on sign-up or sign-in style endpoints.

```json
"tokenize": {
  "type": "JWT",
  "algorithm": "HS256",
  "expiration": 3600,
  "encryption_key": "$ENV.JWT_KEY",
  "custom_claim_fields": ["id", "email"],
  "property_name": "token"
}
```

Supported token types:

* `JWT`
* `PASETO`

For `PASETO`, the encryption key must be 32 characters long.

### Protect an endpoint

Use `protected` when a request must include a valid token.

```json
"protected": {
  "provide_as": "Authorization",
  "extract_claims": ["id"]
}
```

Protected endpoints should also define `tokenize` so Sub0 knows how to verify the token.

Default header format:

```json
"Authorization": "Bearer <token>"
```

Custom header example:

```json
"provide_as": "x-api-key"
```

### Use extracted claims

Claims from a verified token are available through `$PROTECTED`.

```json
"parameters": ["$PROTECTED.id"]
```

```json
"upload_folder": "/gallery/$PROTECTED.id"
```

This keeps access control on the server side.

### What Sub0 verifies

Sub0 validates:

* token signature
* token expiration
* token structure

Invalid or missing tokens return `401 Unauthorized`.

### WebSockets

WebSocket connections can include a `uid` for targeted delivery.

Protected WebSocket resources still require a valid token when the resource is marked `protected`.

Use the connection pattern documented in [Websockets](/sub0/apis-abi/websockets.md).

### Best practices

* Keep secrets in `$ENV`
* Extract only the claims you need
* Protect every state-changing endpoint
* Trust `$PROTECTED.id`, not a user ID from the payload

### Next step

Pair authentication with [Making API Requests](/sub0/apis-abi/making-api-requests.md) to see how clients send protected requests.


---

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