Abstract: An interface for a small form factor electronic device by enabling explicit measurement of extension or retraction of a retractable cord by monitoring the amount of string that passes by sensors, as the string exits the enclosure of the device. Input to such small form factor devices may be provided by sensors that measure the length of a string or wire that has been pulled out of an enclosure, in addition to an angle or direction (e.g., in 1-, 2- or 3-dimensions) at which the string was pulled out. Additionally, the rate of acceleration for the pulling and retracting motion may also be used as additional forms of input. In a further embodiment, a string interface is provided for a small form factor device that communicates information in the form of a pixel display provided integral with the string in response to string manipulation.

Abstract: A portable computing device for opening a door (an electronic door opener) and a method for its use is disclosed. The computing device has a shared secret key, a standard certificate, means for communicating with the door, and a processor adapted for performing operations with shared secret keys and standard certificates. The door also possesses the same shared secret key. Under normal operation, messages encoded with the shared secret key serve to establish a right to open the door. The portable computing device's standard certificate is used to respond to occasional challenges by the door, and to generate the shared secret key. Biometric capabilities of the portable computing device add an additional layer of security in screening the identity of the user of the device. A security system for controlling access, involving a first plurality of computing devices and a second plurality of doors, and operating based on shared secret keys and occasional challenges is also disclosed.

Abstract: An interface for a small form factor electronic device by enabling explicit measurement of extension or retraction of a retractable cord by monitoring the amount of string that passes by sensors, as the string exits the enclosure of the device. Input to such small form factor devices may be provided by sensors that measure the length of a string or wire that has been pulled out of an enclosure, in addition to an angle or direction (e.g., in 1-, 2- or 3-dimensions) at which the string was pulled out. Additionally, the rate of acceleration for the pulling and retracting motion may also be used as additional forms of input. In a further embodiment, a string interface is provided for a small form factor device that communicates information in the form of a pixel display provided integral with the string in response to string manipulation.

Abstract: A portable computing device for opening a door (an electronic door opener) and a method for its use is disclosed. The computing device has a shared secret key, a standard certificate, means for communicating with the door, and a processor adapted for performing operations with shared secret keys and standard certificates. The door also possesses the same shared secret key. Under normal operation, messages encoded with the shared secret key serve to establish a right to open the door. The portable computing device's standard certificate is used to respond to occasional challenges by the door, and to generate the shared secret key. Biometric capabilities of the portable computing device add an additional layer of security in screening the identity of the user of the device. A security system for controlling access, involving a first plurality of computing devices and a second plurality of doors, and operating based on shared secret keys and occasional challenges is also disclosed.