# Error Responses

| Status Code | Error               | Description                                      |
| ----------- | ------------------- | ------------------------------------------------ |
| `401`       | `INVALID_SIGNATURE` | Signature verification failed                    |
| `401`       | `MISSING_SIGNATURE` | Required x-signature header missing              |
| `401`       | `MISSING_CLIENT_ID` | Required x-client-id header missing              |
| `401`       | `TIMESTAMP_TOO_OLD` | Request timestamp is too old (replay protection) |
| `403`       | `INVALID_CLIENT`    | Client credentials are invalid                   |