Systems and methods for conducting convenient and secure mobile transactions between a payment terminal and a mobile device, e.g., in a fueling environment, are disclosed herein. In some embodiments, the payment terminal and the mobile device conduct a mutual authentication process that, if successful, produces a session key which can be used to encrypt sensitive data to be exchanged between the payment terminal and the mobile device. Payment and loyalty information can be securely communicated from the mobile device to the payment terminal using the session key. This can be done automatically, without waiting for the user to initiate a transaction, to shorten the overall transaction time. The transaction can also be completed without any user interaction with the mobile device, increasing the user's convenience since the mobile device can be left in the user's pocket, purse, vehicle, etc.