Apple Pay uses a sophisticated security system that makes it even more secure than using your actual credit card. For starters, you need the PIN and/or fingerprint ID to use Apple Pay on your device. Once you’ve added a card, your payment network/bank issues a Device Account Number that is specific to your device. This is encrypted and sent to Apple (who can’t decrypt it) who then adds it to the Secure Element in your device, along with other information. This Device Account Number is stored in the Secure Element and isolated from iOS. Apple never knows it and it is not backed up to iCloud. Apple also has no access to your credit card numbers – Apple Pay only stores a portion of each card number and Device Account Number.