Asym Jwt

Library for encoding with asymmetrically signed JSON web tokens for the Arduino and ESP8266 platforms. Only supports P-256 Elliptic Curve keys.

Installation

Arduino IDE

1. Download the latest release from the releases page.
2. Unzip the downloaded file.
3. Rename the folder to AsymJwt.
4. Move the folder to your Arduino libraries folder.

PlatformIO

1. Add the library to your platformio.ini file:

lib_deps =
    qube-ai/AsymJwt

Usage

Generating keys

2. Install openssl
3. Install fish shell (optional)
4. Run gen_keys.fish or gen_keys.sh script in the scripts folder.

fish gen_keys.fish

output: 
Generating P-256 Elliptic Curve key pair
Generating private key
Enter device name:
read> Test-2
read EC key
writing EC key
read EC key
writing EC key
Keys have been created.

Uploading keys to the device

1. Upload the private key to the device in DER format.
2. Keep the public key in a safe place.

Arduino IDE

1. Open the Arduino IDE.
2. Open the Tools menu.
3. Select ESP8266 Sketch Data Upload.
4. Select the private key file.
5. Click Upload.

PlatformIO

1. Create a data folder in the root of your project.
2. Copy the private key file into the data folder. (The above script will create a private-key.der file inside data/.)
3. Add the following to your platformio.ini file (Optional):

[env:your_env]
build_flags = -D PIO_FRAMEWORK_ARDUINO_LWIP2_HIGHER_BANDWIDTH
upload_flags = --upload-port $UPLOAD_PORT --upload-file data/private-key.der

or

4. Go to PlatformIO Home > your_env > Platform > Build Filesystem Image > Upload Filesystem Image

Using the library

#include <Arduino.h>
#include <AsymJwt.h>


void setup()
{
  Serial.begin(9600);
  Serial.println("Reading private ket....");
  while (!AsymJWT::readPrivKey("/private-key.der"))
  {
    Serial.println("Failed to read private key. Retrying in 2 seconds");
    delay(2000);
  }
}


void loop()
{
  time_t iat = time(nullptr);
  String payload = "{\"iat\":" + String(iat) + ",\"exp\":" + String(iat + 300) + ",\"thing_id\":\"" + "THING_ID" + "\"}";
  Serial.println(AsymJWT::generateJwt(payload));
  delay(200000);
  Serial.println("Refreshing JWT.");
}

License

This project is licensed under the UnLicense - see the LICENSE file for details

Configuration

• Enable debug mode by defining ASYMJWT_DEBUG before including the library.

  #define ASYMJWT_DEBUG 1
  
  #include <AsymJwt.h>

TODO

• Add support for decoding JWTs (currently only encoding is supported)
• Add support for other key types
• Add support for other hashing algorithms