Andrew Richardson on how he thinks Apple’s new EasyPay feature may work:

Combine the authorized-by-EasyPay transaction record, the customer’s location within the store as reported by the app, and an RFID tag inside the product box. An automated system can determine which products may pass through the security portal without sounding an alarm and which cannot. The key is the customer’s phone.Hand the paid-for product to your buddy and hear the alarm sound as he walks out the door without your iPhone in hand.

I have no idea how it works and how they stop people from stealing.