Abstract: A logic structure adapted to receive pulsed active input signals produces a logical output with a very small inherent switching delay. Pull-down transistors and complementary pull-up transistors are ratioed such that the default logical output level remains close to nominal even when the logic structure sinks or sources a DC current. When the pulsed input signals are inactive, no DC current path is enabled.

Abstract: A method and apparatus in accordance with the present invention, in response to a request for access to a secure resource, modulates an illumination light source, such as a computer display, in a pseudo-random sequence to produce time-varying light emissions that reflect off of the object being imaged by an image recognition system. The authentication system controls both the generation of the modulated light emissions and the detection of their reflection from the object, in real time. This prevents an adversary from spoofing a visual authentication system by replaying recorded images. In further aspects of the present invention, combinations of visible and infrared illuminations may be used.

Abstract: A cryptographic system and method for secure distribution and management of cryptographic keys for use in a DVD copy protection scheme is disclosed. A DVD disc having compressed, encrypted content written on a first portion of the disc, and the content encryption key, itself encrypted with a second key and written out of band on a second portion of the disc is used to provide content, key, and control information to a DVD drive according to the present invention. The DVD drive is coupled to a decompressor and a video controller. The video controller and DVD drive engage in a handshaking protocol in which all of the communication between them is encrypted. After verifying that the video controller is registered and not known to be compromised, the DVD drive passes the content key and control information to the video controller, and the compressed, encrypted content to the decompressor.