Using Chrome, and Developer tools, you can see all this happening live.

Ĩ- The interface is now redraw to look like the WhatsApp app, and you continue to receive data on the WS, and sending when needed, and updates are made to the interface as data is arriving on the WS. So, to let the Servers know that the WS session belongs to a specific phone, you need to use the phone for QR readingģ- You grab your phone, which is authenticated (otherwise you wouldn't have access to the section to scan QR codes), and do the QR Code reading thingĤ- When your mobile reads the QR code, it contacts the WhatsApp servers and tells them : My number is XXXX, My auth creds are YYYYY, and the WS associated with this QR code can now receive my DATAĥ- The server now knows that it can direct Traffic to the specific WS socket that belongs to that QR Code, and does so !Ħ- On the Browser WS you can see the Server sending data regarding the user, regarding the conversations that you are having and which photo thumbnails to go and Grab.ħ- The Browser gets this data from the WebSocket, and makes the corresponding GET requests to get the Thumbs, and other resources it needs, like an MP3 for notificationsħ.1 - The WS listener on the Browser also makes Javascript calls, on the javascript files that were received at step 1, to redraw the page DOM with the new interface. It also does not require you to type it, because the server wouldn't be sure that the number really belongs to you. At this stage your browser is ready do the WhatsApp App work, but it does not know what is your ID (Whatsapp identifier which is your mobile number), because it can't really get you phone number from thin air. Ģ.3 - Notice that this specific WS that the server has open between the Server and the Browser is associated with the unique QR code !!! So, knowing the QR code, the server knows which WS is associated with it! This is sent by the Server to the Browser, throught the WebSocket (WS we call it from now onwards)Ģ.2- On each QR Code refresh received on the WS, your browser does a GET request for the new QR Code in BASE64 encode.

1- You open the following URL on your browser : Ģ- The Browser loads the page with all sorts of JS and CSS stuff, but also opens a WebSocket ( wss://w4./ws ) - Check this image :Ģ.1- Every 20000 milliseconds you see traffic on the WebSocket for a refresh on the QR code you have on you screen.

Whatsapp login qr code scan