Info on the key service error.

| Enums ||
|---|---|
| `KEY_SERVICE_ERROR_INFO_UNSPECIFIED` | Error info not specified. |
| `MALFORMED_JSON` | The response has malformed JSON. |
| `MISSING_KEY` | The response did not contain the wrapped/unwrapped key. |
| `MISSING_SIGNATURE` | SMIME sign only: The sign response did not contain the signature. |
| `MISSING_ALGORITHM_NAME` | SMIME only: The sign response does not include the algorithm name. |
| `UNSUPPORTED_ALGORITHM` | SMIME only: the algorithm name in the response is not supported by the client. |
| `FETCH_REQUEST_ERROR` | Fetch request on the client has failed. |
| `SERVER_SIDE_FETCH_REQUEST_ERROR` | Fetch request from the Google server to the key service has failed. |