3DS response data above and beyond token data

[ianbjacobs]

At yesterday's 3DS task force call [1], it was suggested that if a browser or third party payment handler initiates 3DS flows, it may be necessary to include additional data (above and beyond token data, for example) in the response, namely: 3DS crypto and XID data.

This issue is a place-holder for that discussion.

Ian

[1] https://www.w3.org/2018/02/27-wpwg-minutes.html