Change payment amount from SPC call within a payment app?

[w3c]

Change payment amount from SPC call within a payment app?

[danyao]

• User agrees with merchant to pay $100

What constitute an "agreement"? Who, if any, needs to be able to verify this "agreement" took place?

• When user chooses payment method, the payment method supports installments (e.g., $25 every week)
• The SPC transaction window should say "Do you agree to pay $25?"

This sounds like the browser UI should display $25. What would be the amount that the issuer wants to see in the Transaction Confirmation / Dynamic Linking signature?

• Subsequent payments are handled by card-on-file

Do these subsequent payments need to carry Dynamic Linking signatures?

[ianbjacobs]

cc @frank-hoffmann

[ianbjacobs]

The way the API has evolved, if it is callable at all in a payment handler, then it is callable with data provided by the payment handler. So the answer to the original issue is "Yes, the payment handler can specify a total that is different from what the merchant displayed." The resulting assertion will include the signed data that was displayed, and the RP can accept or reject it.