Data Masking in SAP MDG-S

Hello Experts,

Could anyone please throw some light of how can we mask the data values in MDG, like there is a bank account number field which is having value as "123455", but in workflow for one of the approver we want that this field should be visible as "12XXXX".

How this can be achieved?

Any useful pointers will,be appreciated.

Regards

Prateek