Abstract: Techniques are disclosed relating to authentication for user transactions. In some embodiments, a first device of the user provides an option for the user to transfer payment and device signature information to a second device of the user. The second device, in some embodiments, then uses the payment information for payment transactions (which may avoid manual input of payment information). The second device, in some embodiments, transmits the device signature information for the first device to an authentication system. The authentication system, in some embodiments, authenticates the second device based on a match for the signature information for the first device.

Abstract: A user interface of an automated teller machine receives a first input that identifies a transaction type. Next, a near field communication reader of the ATM detects a first near field communication message from a first mobile device so that the automated teller machine can extract a first account identification information from that message. The first account identification information comprises data related to a first account associated with a first user. A second NFC message from a second mobile device associated with a second user is detected in order to extract a second account identification information from the second NFC message. The second account identification information comprises data related to a second account associated with the second user. Once the ATM has the needed information, it can initiate a transaction based on the transaction type, the first account identification information, and the second account identification information.

Abstract: A method for alternate primary account number generation is described. The method comprises receiving, from a device, an input data string containing sensitive data. The input data string comprises a first portion, a second portion, and a third portion. A plurality of values is generated using the second portion of the input data string, wherein each of the plurality of values are of a predetermined amount of numbers, each of the plurality of values having a corresponding key. A first key is selected, based on the second portion, from the plurality of values. A second key is generated using the first key. An output value is selected, based on the second key, from the plurality of values. An output data string is generated using the first portion, the output value, and the third portion.