IoTHub device SASToken generation in react-native application

Question

Hi,

In microsoft document (https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-dev-guide-sas?tabs=node#sas-token-structure) the method to generate the Azure IoTHub device SAS Token is provided for Node.js platform using crypto. But the same method is failing in react-native application.

Can anyone suggest a method/library which will work on react-native application?

Note: I have tried using react-js npm module using below method

import CryptoJS from 'crypto-js'  
  
var hmac = CryptoJS.algo.HMAC.create(CryptoJS.algo.SHA256, deviceKey);  
hmac.update(stringToSign);  
var hash = CryptoJS.enc.Base64.stringify(hmac.finalize());  
 console.log('hash: ', hash)  

But the signature generated with above method is failing to authenticate with IoTHub device.

Answer 1

Hello @Naveen Kumar Jain S ,

Most likely, it is an encoding problem of the key and URI. You can try the following code:

var hmac = CryptoJS.algo.HMAC.create(CryptoJS.algo.SHA256, CryptoJS.enc.Base64.parse(deviceKey));   
hmac.update(stringToSign);   
var hash = encodeURIComponent(CryptoJS.enc.Base64.stringify(hmac.finalize()));  
console.log("hash: ", hash);  
  

Answer 2

Hi @chbeier ,

Actually I had also tried this combination where Base64 encoded deviceKey is used for HmacSHA256 generation.

I was able to generate device SAS token which is correctly authenticated with IoTHub by following the below blog.

https://javascript.plainenglish.io/using-core-node-js-modules-in-react-native-apps-e6002a33b6ff

Thank you for following my question.