A system comprising a first device, the first device comprising: at least one processor; and a memory configured to store instructions that, when executed by the at least one processor, cause the first device to: perform a first comparison between a first sensor signature associated with first set of sensor data of the first device in a first context and a second sensor signature associated with second set of sensor data of a second device, the first comparison associated with a first authentication type, and wherein the first device is a wearable device worn by a user and the second device is a mobile device; determine a first comparison value based on the first comparison between a first sensor signature and the second sensor signature, wherein the sensor data relates to motion of the first device and the second device and is provided by at least one of a GPS sensor, an accelerometer, and a gyroscope; determine whether the first comparison value satisfies a first threshold based upon a similarity between the first set of sensor data associated with the first context and the second set of sensor data; determine the user should be authenticated on the second device based on satisfaction of the first threshold; characterised by the instructions causing the first device to: provide a password for the second device to the second device to authenticate the user on the second device, when the first threshold is satisfied; request manual input of the password for the second device, when the first threshold is not satisfied; receive an input from the user; and based on a determination that the input corresponds to the password, update the first threshold. at least one processor; and a memory configured to store instructions that, when executed by the at least one processor, cause the first device to: perform a first comparison between a first sensor signature associated with first set of sensor data of the first device in a first context and a second sensor signature associated with second set of sensor data of a second device, the first comparison associated with a first authentication type, and wherein the first device is a wearable device worn by a user and the second device is a mobile device; determine a first comparison value based on the first comparison between a first sensor signature and the second sensor signature, wherein the sensor data relates to motion of the first device and the second device and is provided by at least one of a GPS sensor, an accelerometer, and a gyroscope; determine whether the first comparison value satisfies a first threshold based upon a similarity between the first set of sensor data associated with the first context and the second set of sensor data; determine the user should be authenticated on the second device based on satisfaction of the first threshold; characterised by the instructions causing the first device to: provide a password for the second device to the second device to authenticate the user on the second device, when the first threshold is satisfied; request manual input of the password for the second device, when the first threshold is not satisfied; receive an input from the user; and based on a determination that the input corresponds to the password, update the first threshold. perform a first comparison between a first sensor signature associated with first set of sensor data of the first device in a first context and a second sensor signature associated with second set of sensor data of a second device, the first comparison associated with a first authentication type, and wherein the first device is a wearable device worn by a user and the second device is a mobile device; determine a first comparison value based on the first comparison between a first sensor signature and the second sensor signature, wherein the sensor data relates to motion of the first device and the second device and is provided by at least one of a GPS sensor, an accelerometer, and a gyroscope; determine whether the first comparison value satisfies a first threshold based upon a similarity between the first set of sensor data associated with the first context and the second set of sensor data; determine the user should be authenticated on the second device based on satisfaction of the first threshold; provide a password for the second device to the second device to authenticate the user on the second device, when the first threshold is satisfied; request manual input of the password for the second device, when the first threshold is not satisfied; receive an input from the user; and based on a determination that the input corresponds to the password, update the first threshold.