PPSE and CRS relation when using INTERNAL mode

Question

When use Internal mode of PPSE (Proximity Payment System Environment) I found that CRS(Contactless Registry Service) is coming to play in the process of Application selection. But could not found exact details about logical dependecy of each other.

Could anyone explain the logical relation of PPSE and CRS at Application selection process when PPSE is set to Internal mode?

Answer 1

There are two CRS-related concepts : the CRS as a registry within the card, and the CRS application which exposes the former to device a application (typically EMV's AAUI) to display the configuration and query user's choice. Currently the CRS application is an optional part of the standard.

The PPSE's role is to expose a list of payment applications to the point of sale (PoS). In order to do this, it listens to application activation events that are broadcast by the CRS (register). For this to work the banking apps will be instantiated specifying explicitly the PPSE as a destinator of their activation events. In EMV "internal mode", bank apps typically have the contactless self-activation priviledge, which means that the bank mobile app will send a set-status command to the banking card app, which activates itself using the CRS APIs. In turn the CRS will broadcast this event to all authorised registered listeners, including the PPSE.

On top of that, in some markets, another application receives the broadcast in order to implement a market-specific policy. For instance AEPM requirements (which apply broadly in Europe) state that the PPSE's response shall only ever contain one application at a given point in time. To enforce this rule, there is a dedicated application (AEPM CREL) which will deactivate all other apps but the latest activated.

This is described in details in the EMVCo and AEPM specifications. CRS is covered in details in GlobalPlatform's Amendment C to the card specification.