ClearBlade IoT Enterprise supports various types of authentication.

Active key authentication

A ClearBlade user token is required to communicate with a broker. A token can be obtained via a REST endpoint call or MQTT.

Connect

Subscribe

• To receive the new JWT token, subscribe to the auth topic (recommended).

• To receive the legacy token, subscribe to the v/1/auth topic.

Extract token

• ClearBlade publishes the user token on the auth message topic with bit-level encoding.

• The payload is in this format:

• The length block is a 2-byte unsigned 16-bit integer.

• The data block is UTF-8 encoded bytes.

Block mapping in the above packet structure:

Once the client is authenticated, the token can be extracted, and the connection can be established.

Error codes

Referring to MQTT 3.1.1 spec

Public key (asymmetric) authentication

A device must create a private/public key pair. The private key is only left local on the device, while the public key is uploaded to the ClearBlade IoT Enterprise system’s device record.

See Creating key pairs to create the key pair.

To authenticate, the device will construct a JSON Web Token (JWT) based on the private key and present that on the MQTT authentication or REST endpoint’s connect packet. The JWT is used in place of the standard ClearBlade auth token.

• The device uses the private key to sign the JWT. The token is passed to ClearBlade IoT Core as proof of the device's identity.

• The service uses the device’s public key (uploaded before the JWT is sent) to verify the device's identity.

To add the public key to the device, use the following steps and example images:

1. Find the device in the system’s device table:
   

   

2. Right-click the device’s gear icon and choose Public Keys, then click the Add button:
   

   

   

3. Pick the appropriate key format:
   

   

   ClearBlade IoT Core supports the RSA and elliptic curve algorithms. For details on key formats, see Public key format.

Claims

ClearBlade IoT Enterprise requires these reserved claim fields. They may appear in any order in the claim set.

The optional nbf(not before) claim will be ignored.

A JSON representation of the required reserved fields in a ClearBlade IoT Core JWT claim set is shown below:

{
  "aud": "my-project",
  "iat": 1509654401,
  "exp": 1612893233
}

Only devices will be supported with this method.

Each time the client sends an MQTT message (including PINGREQ), the ClearBlade MQTT Broker checks the exp. If the current time is later than exp + 10m then the client will disconnected. The 10 minutes is to allow for time skew between client and server.

The Python file shows an example of generating a JWT for the MQTT client’s password.

mTLS

Devices may connect using an mTLS approach to gain their access token. ClearBlade handles mTLS auth and TLS termination.

Currently, no user interface administration is available to manage the loaded certificates. All certificates must be loaded to the server via API calls.

Requirements

The device name must be the cn (common name) in the cert presented. The platform verifies that the certificate passed in is for the device.

APIs

/admin/settings/mtls

GET, PUT (upsert), and DELETE support. Admin only.

PUT:

Body required:

{"root_ca": "certificate in PEM format. <required>", "crl": "certificate revocation list in PEM format. <optional>"}

Returns nil on success

GET:

No query support. Get the latest mTLS settings in JSON:

{"root_ca": "certificate in PEM format", "crl": "certificate revocation list in PEM format"}

DELETE:

No query support. Deletes mTLS settings.

/admin/revoked_certs

GET, POST, and DELETE support. Admin only.

POST:

Use to revoke a certificate. Body required:

{
“certificate_hash”: "sha256 hash of the ASN.1 DER format of the certificate <required>",
"description": <optional>
}

Returns nil on success.

GET:

Query supported. An empty query gets all revoked certificates, including those that match the query.

[
{"id": <id1>, "certificate_hash": <certificate1_hash>, "timestamp": <timestamp1>},
{"id": <id2>, "certificate_hash": <certificate2_hash>, "timestamp": <timestamp2>}
]

DELETE:

Query supported. An empty query deletes all revoked certificates and returns nil on success.

Authentication

A device can authenticate (i.e., receive a token) using mTLS by sending an HTTP POST request to port 444 of the relevant URL.

The following curl can be used as an example:

curl -X POST "https://yourURL.com:444/api/v/4/devices/mtls/auth" -H 'Content-Type: application/json' -H 'Accept: application/json' -d '{"system_key": "yourSystemKey", "name": "yourDeviceName"}' --cert "path/to/yourDeviceCert.pem" --key "path/to/yourDeviceKey.pem"

The returned response will contain a device token.

Similarly, this Python code can be used as an example:

import requests

url = "https://yourURL.com:444/api/v/4/devices/mtls/auth"
headers = {"Content-Type": "application/json", "Accept": "application/json"}
data = '{"system_key": "yourSystemkey", "name": "yourDeviceName"}'
resp = requests.post(url, headers=headers, data=data, verify=True, cert=("path/to/yourDeviceCert.pem", "path/to/yourDeviceKey.pem"))

deviceToken = str(resp["deviceToken"])

ALPN (Application Layer Protocol Negotiation)

ClearBlade supports mTLS authentication for devices connecting via MQTT using ALPN on port 444. The ALPN protocol name is clearblade_mqtt_mtls. Device Just-in-Time (JIT) provisioning is also supported. A Root CA certificate must be added via the mTLS admin endpoints before connecting devices via mTLS.

To connect to MQTT using mTLS, the device needs to set the following in the MQTT Connect packet:

1. The Username field must be a stringified JSON object with the device name set, amongst other column values, if required for JIT provisioning. For example: '{"name": "myDevice"}'

2. The Password field must contain the system key.

Here’s a Python example using the Paho MQTT client:

from __future__ import print_function
import sys
import ssl
import time
import datetime
import logging, traceback
import paho.mqtt.client as mqtt
IoT_protocol_name = "clearblade_mqtt_mtls"
cb_iot_endpoint = "<CLEARBLADE_URL>" # For example test.clearblade.com
cert = "<DEVICE_CERTIFICATE_FILE>"
private = "<DEVICE_PRIVATE_KEY_FILE>"
username = '{"name": "device-1"}'
password = "<SYSTEM_KEY>"
logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
handler = logging.StreamHandler(sys.stdout)
log_format = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(log_format)
logger.addHandler(handler)
def ssl_alpn():
    try:
        #debug print opnessl version
        logger.info("open ssl version:{}".format(ssl.OPENSSL_VERSION))
        ssl_context = ssl.create_default_context()
        ssl_context.set_alpn_protocols([IoT_protocol_name])
        ssl_context.load_cert_chain(certfile=cert, keyfile=private)
        return  ssl_context
    except Exception as e:
        print("exception ssl_alpn()")
        raise e
if __name__ == '__main__':
    topic = "test/date"
    try:
        mqttc = mqtt.Client(client_id="<CLIENT_ID>")
        ssl_context= ssl_alpn()
        mqttc.tls_set_context(context=ssl_context)
        mqttc.username_pw_set(username=username, password=password)
        logger.info("start connect")
        mqttc.connect(cb_iot_endpoint, port=444)
        logger.info("connect success")
        mqttc.loop_start()
        while True:
            now = datetime.datetime.now().strftime('%Y-%m-%dT%H:%M:%S')
            logger.info("try to publish:{}".format(now))
            mqttc.publish(topic, now)
            time.sleep(1)
    except Exception as e:
        logger.error("exception main()")
        logger.error("e obj:{}".format(vars(e)))
        logger.error("message:{}".format(e.message))
        traceback.print_exc(file=sys.stdout)