Example: Using the JSON Web Token SL Library

Product: CODESYS IIOT Libraries SL

The JSON Web Token SL Example.project sample project, which includes a visualization to create a JWT (JSON Web Token) on a controller, shows how to use the JSON Web Token SL library.

Parameters

Internal memory has to be reserved in order to create a JWT. For this purpose, the amount of reserved memory has to be at least the size of the JWT. The maximum size can be changed in the Library Manager by means of a parameter list of the library (see Image 1).

Procedure. Getting Started

Create a private key.
A private key is required for the asymmetric signature algorithm (RS256).
1. To do this, you first need to install the CODESYS Security Agent add-on.
2. After that, you can use the Security Screen to create a new certificate on the device.
  The Common Name of the certificate is then passed to the JWT library.
Download the project to a controller and start the application.

Description

The JSON Web Token SL library contains a function block to create a JWT (JSON Web Token) on the controller. For this purpose, the HS256, HS384, HS512, and RS256 algorithms are supported.

Application: `JWT`

For symmetric signature algorithms (HS256, HS384, HS512):

Use the sSecret input.
Leave the sUseCaseName and sCommanName inputs blank.

For asymmetric signature algorithms (RS256):

Specify the data of the certificate in the sUseCaseName and sCommanName inputs.
Leave the sSecret input blank.

Visualization of the `JWT` example

System requirements and restrictions

Programming system	CODESYS Development System (version 3.5.18.0 or higher)
Runtime system	CODESYS Control Win (version 3.5.18.0)
Add-on components	-

Note

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