The demo app with info about how to use this extension is available, to learn more about HS256 signing read below article,

https://auth0.com/docs/get-started/applications/signing-algorithms

Also to understand difference between JWT, JWS,JWE and JWk refer below article,

https://medium.com/@goynikhil/what-is-jwt-jws-jwe-and-jwk-when-we-should-use-which-token-in-our-business-applications-74ae91f7c96b

This extension uses JOSE package internally for encoding and decoding.

The extension SignJSONUsingHS256 is used for signing a text using HS256 scheme. It has two server action Signing and VerifyAndDecrypt.

The first server action expects JSON/normal text as input and key that will be used for signing the input text. In response this action gives signed text which has three parts, Header-Payload-Signature. we can use this and pass as request in secure API calls such as that of Payment Gateway.

The next action is the VerifyAndDecrypt, this action verify whether the given signed payload is correct and if it is verified, It'll decrypt it and return us the Original JSON/text.

The signed text has two headers by default : "alg": "HS256",  "typ": "JWT"

One can go to jwt.io to decode the header and payload as shown below in scrrenshot,