want to developer a simple app can
1) store user credit number, storing card number on user phone is ideal (use cache)
2) have 4 digit login pin for user (see upload photo)
.png?1447563302]
3) can only browse my eCommerce site (site similar to grubhub)
4) when during check out, user can apply credit number store on their phone with just a "tap"
Please provide answer in detail. thanks you