Abstract: Computer recognition is performed to recognise whether a user interacting with a user device in an identified interval of time is the same user as a user that has interacted with the device at other times. First user behaviour data is derived by processing first data representative of a user interacting with the user device, generated by a plurality of different elements of the user device including a sensor. At least a first interval of time is identified relating to an interaction of a user with the user device. Second user behaviour data is derived by processing second data representative of a user interacting with the user device during at least the first interval of time. User verification data, based on the first user behaviour data and the second user behaviour data, is transmitted from the user device to an interaction verification system.