A device for defining or verifying a password by touch-less gesture, the device comprising: two or more ambient light sensors arranged at respective surface locations of the device, each of the two or more ambient light sensors configured to measure light intensity at the respective surface location; a first processor configured to execute a password application on the device; and a second processor configured to detect two or more touch-less gestures performed by an object that changes light intensity in a zone of detection of one or more of the ambient light sensors, wherein the object is a hand or one or more fingers of a user, the object being spaced from the two or more ambient light sensors such that there is no contact between the object and the two or more ambient light sensors; wherein the second processor is configured to define or verify a password based on the two or more touch-less gestures performed by the object, wherein the second processor is configured to detect the two or more touch-less gestures using light intensity measurements obtained from the two or more ambient light sensors, wherein the device is configured to not emit light for the purpose of gesture detection; wherein the second processor is configured to verify the password against the defined password when a password entry option of the password application is initiated, and responsive to verifying the password, the second processor is configured to: generate a signal to unlock functionality of a domain associated with the password, the password being associated with the domain during the password definition processing; the domain being one of multiple domains specified in the device, each of the multiple domains having a unique password to unlock functionality of each respective domain, wherein each of the domains have one or more applications and settings of the device associated with them. two or more ambient light sensors arranged at respective surface locations of the device, each of the two or more ambient light sensors configured to measure light intensity at the respective surface location; a first processor configured to execute a password application on the device; and a second processor configured to detect two or more touch-less gestures performed by an object that changes light intensity in a zone of detection of one or more of the ambient light sensors, wherein the object is a hand or one or more fingers of a user, the object being spaced from the two or more ambient light sensors such that there is no contact between the object and the two or more ambient light sensors; wherein the second processor is configured to define or verify a password based on the two or more touch-less gestures performed by the object, wherein the second processor is configured to detect the two or more touch-less gestures using light intensity measurements obtained from the two or more ambient light sensors, wherein the device is configured to not emit light for the purpose of gesture detection; wherein the second processor is configured to verify the password against the defined password when a password entry option of the password application is initiated, and responsive to verifying the password, the second processor is configured to: generate a signal to unlock functionality of a domain associated with the password, the password being associated with the domain during the password definition processing; the domain being one of multiple domains specified in the device, each of the multiple domains having a unique password to unlock functionality of each respective domain, wherein each of the domains have one or more applications and settings of the device associated with them. generate a signal to unlock functionality of a domain associated with the password, the password being associated with the domain during the password definition processing; the domain being one of multiple domains specified in the device, each of the multiple domains having a unique password to unlock functionality of each respective domain, wherein each of the domains have one or more applications and settings of the device associated with them.