This method used to simplify other IoT node such as ESP8266 and ESP32 or the others. Just send to this gateway via MQTT and... voila... it is on Tangle. As default, this code work on Chrysalis Devnet. If you want to use in production, please install hornet or collaborate with someone who has a hornet API to Chrysalis Mainnet.

• Python 3.x
• pip

• Install Mosquitto

sudo apt-get install mosquitto
sudo apt-get install mosquitto-clients

• Install Paho MQTT

pip install paho-mqtt

Since newer mosquitto didn't support anonymous message, you need to allow it manually.

sudo nano /etc/mosquitto/mosquitto.conf

and add this lines

listener 1883
allow_anonymous true

• Digital Signature

pip install starkbank-ecdsa

When start subscribing MQTT topic, it will fetch latest message in topic. This is called retained message. If retained message is on, gateway will create new IOTA submission every time gateway is started. This will create duplicate data. To prevent gateway from this action, please follow steps below.

• Open terminal and type

sudo nano /etc/mosquitto/mosquitto.conf

• Change value of persistance from true to false

persistence false

• Stop mosquitto and start again

sudo service mosquitto stop
sudo service mosquitto start

• Open terminal and

git clone https://github.com/SuryaAssistant/iota-raspberrypi-gateway

• Go to src folder and run the program

cd iota-raspberrypi-gateway/src
python3 main.py

When you start the program from terminal, it will show you a gateway id.

• You need to subscribe MQTT topic to receive response from the gateway (Optional)

  • On linux or Windows
    • Syntax

    mosquitto_sub -h test.mosquitto.org -t "<your_gateway_id>/<your_return_topic>"
    

    • Example :

    mosquitto_sub -h test.mosquitto.org -t "0xb827eba5f9f6/myTopic"
    

• For upload process, run the step below

  • On Linux or Windows

    • Syntax

    mosquitto_pub -h test.mosquitto.org -t "0xb827eba5f9f6/submit" -m "data/{<your_data>}/<your_return_topic>"
    

    • Example : It is real warning, don't use " for json format, use ' instead.

    mosquitto_pub -h test.mosquitto.org -t "0xb827eba5f9f6/submit" -m "data/{'node':'node1','encrypt_data':'xasdjkafadhdioasid1'}/mytopic"
    

  • On ESP based microcontroller, the topic to publish is 0xb827eba5f9f6/submit and message format used is data/{<your_data>}/<your_return_topic>.

Other features are following MQTT Message Syntax section.

This project used secp256k1 elliptic curve to generate private key and public key. We are using python starkbank-ecdsa library to generate and validate digital signature for the data. When you run the main.py for the first time, it will generate private key automatically and store the private key. As long as not re-installed, private key will still remain there.

The data that signatured is in yellow box. The result is in base64 format signature. Format to validate the signature is defined below

Data : "message":{"timestamp":1686382764,"uuid":"0xb827eba5f9f6","data":{"node":"esp32-client-78:21:84:88:63:10","nodeTimestamp":1686382764,"temperature":40.60,"humidity":43.00}}
Data is without whitespace

Public Key (compressed) : 02fc8d163ee74b6e972bcc94481d0006f13c8e20896087fbfbda3ebc326ce2269b

Public Key PEM Format :

-----BEGIN PUBLIC KEY-----
MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAE/I0WPudLbpcrzJRIHQAG8TyOIIlgh/v7
2j68MmziJpt+3/KrkvZ8CecdV53OXlOLNBRfU7ZtKbRSLOZQPAsBoA==
-----END PUBLIC KEY-----

Signature (base64) : MEUCIQDYFt7gzj3iXOSk1HcN9SW1pNr/js+oWePcD8sVb0VtYAIgdvC+x5jcjB2leSp51p+81A/lhpB3oDMg7634GpPGBUY=

For prooving, you can go here

When you want to use this code in production, please modify the configuration in config/config.py.

• MQTT Broker

  Since this example using free to use MQTT Broker that have some limitations, please change config.py

  mqtt_addr = "<your_premium_broker>"
  

• IOTA Hornet Node Change url from chrysalis devnet to hornet url that connect to mainnet in config.py

  chrysalis_url = "<your_mainnet_hornet_address>"