EMV 3-D Secure (3DS) - Payment Authentication Protocol 5.8.2: 5.8.2 Browser challenge window (Req 5.81 to 5.86)

The 3DS Requestor selects the iframe size from the Challenge Window Size values (Req 5.81), uses a server-authenticated TLS session to the ACS (Req 5.82), creates the challenge window by building the CReq, creating the iframe and posting through it to the ACS URL from the ARes (Req 5.83), with the chosen window size in the CReq (Req 5.84); the ACS answers the CReq with the code that renders the challenge in the iframe, possibly over several interactions (Req 5.85), and after the RReq/RRes exchange posts the final CRes to the notification URL; the 3DS Requestor then closes the challenge window by reloading the parent page and taking out the iframe (Req 5.86).