EMV 3-D Secure (3DS) - Payment Authentication Protocol 4.3: 4.3 Browser UI: processing screen and challenge window content (Req 4.32 to 4.43)

The 3DS Requestor website shows a processing screen during the AReq/ARes cycle with a graphical progress element, the DS logo unless asked not to, no other design element and a minimum display of two seconds (Req 4.32 to 4.36), and is responsible for the iframe's size and placement (lightbox or inline). The ACS keeps HTML versions for every Challenge Window Size value and returns the one matching the size requested (Req 4.37), shows its own processing screen during the CReq/CRes cycle with the same rules (graphic, DS logo unless asked not to, nothing else, at least two seconds; Req 4.38 to 4.42), and uses a commercial certificate authority supported by the major browsers (Req 4.43).