| 摘要 |
A method for determining when a device is in contact with a user, comprises activating S102 an accelerometer provided at the device; activating S103 a vibration motor provided at the device; measuring S104 with the accelerometer vibrations at the device created by the vibration motor; and using S107 the accelerometer measurements to determine whether the device is in contact with a user. The device may be a trusted device in the form of a wristwatch (1, Fig. 1) having an authentication sensor (4, Fig. 1). The device may request re-authentication of the user if it is determined that the device is not in contact with the user. The measurements may be used to determine a probability that the device remains in contact with the user. The calculation of the probability may additionally be based of other sensor measurements e.g. heart-rate, temperature, proximity, photo-detector, biometric, chemical characteristics, motion. A level of trust may be determined. |
