A method for selecting an authentication process for identifying and/or authenticating a user on a device, the method comprising: (a) selecting a first authentication process from a set of authentication processes; (b) passively testing the availability of the selected first authentication process for use in identifying and/or authenticating the user, comprising: identifying a sensor device configured to capture data for the first authentication process; passively enabling the identified sensor device so as to measure one or more environmental parameters; and determining, in dependence on the measured parameters, whether the identified sensor device is capable of capturing data sufficient for performing the first authentication process; (c) if it is determined that the identified sensor device is capable of capturing data sufficient for performing the first authentication process, then: indicating that the first authentication process is available for identifying and/or authenticating the user on the device; (d) if it is determined that the identified sensor device is not capable of capturing data sufficient for performing the first authentication process: selecting a second authentication process from the set of authentication processes; and passively testing the availability of the selected second authentication process for use in identifying and/or authenticating the user, comprising: (i) identifying a second sensor device configured to capture data for the second authentication process; (ii) passively enabling the identified second sensor device so as to measure one or more environmental parameters; and (iii) determining, in dependence on the measured parameters, whether the identified second sensor device is capable of capturing data sufficient for performing the second authentication process. (a) selecting a first authentication process from a set of authentication processes; (b) passively testing the availability of the selected first authentication process for use in identifying and/or authenticating the user, comprising: identifying a sensor device configured to capture data for the first authentication process; passively enabling the identified sensor device so as to measure one or more environmental parameters; and determining, in dependence on the measured parameters, whether the identified sensor device is capable of capturing data sufficient for performing the first authentication process; identifying a sensor device configured to capture data for the first authentication process; passively enabling the identified sensor device so as to measure one or more environmental parameters; and determining, in dependence on the measured parameters, whether the identified sensor device is capable of capturing data sufficient for performing the first authentication process; (c) if it is determined that the identified sensor device is capable of capturing data sufficient for performing the first authentication process, then: indicating that the first authentication process is available for identifying and/or authenticating the user on the device; (d) if it is determined that the identified sensor device is not capable of capturing data sufficient for performing the first authentication process: selecting a second authentication process from the set of authentication processes; and passively testing the availability of the selected second authentication process for use in identifying and/or authenticating the user, comprising: (i) identifying a second sensor device configured to capture data for the second authentication process; (ii) passively enabling the identified second sensor device so as to measure one or more environmental parameters; and (iii) determining, in dependence on the measured parameters, whether the identified second sensor device is capable of capturing data sufficient for performing the second authentication process. selecting a second authentication process from the set of authentication processes; and passively testing the availability of the selected second authentication process for use in identifying and/or authenticating the user, comprising: (i) identifying a second sensor device configured to capture data for the second authentication process; (ii) passively enabling the identified second sensor device so as to measure one or more environmental parameters; and (iii) determining, in dependence on the measured parameters, (i) identifying a second sensor device configured to capture data for the second authentication process; (ii) passively enabling the identified second sensor device so as to measure one or more environmental parameters; and (iii) determining, in dependence on the measured parameters, whether the identified second sensor device is capable of capturing data sufficient for performing the second authentication process.