Abstract: Ingress noise from subscriber equipment is mitigated or prevented from reaching a cable television (CATV) network. All upstream signals including ingress noise are initially transmitted to the CATV network whenever their instantaneous power exceeds a threshold which typically distinguishes ingress noise from a valid upstream signal. Whenever the instantaneous power is below the threshold, ingress noise is blocked from reaching the CATV network. A gas tube surge protection device is included to resist component destruction and malfunction arising from lightning strikes and other high voltage, high current surges.

Abstract: An access control processor provides for display of a message related to an authorization status of an information receiver in a conditional access system for receiving an information segment when the information segment is provided separately by each of a plurality of different service providers. The processor processes a plurality of authorization signals respectively related to the information segment provided separately by the plurality of different service providers; determines which of a plurality of different possible authorization statuses is applicable for the received information segment for each of the respective authorization signals related to the different service providers; selects one of the determined statuses in accordance with a predetermined priority; selects from a plurality of different possible authorization status messages the message applicable to the status determined in accordance with said priority; and provides the selected message for display.

Abstract: An access control processor for a conditional access system. The processor includes a decryptor in an information receiver for decrypting encrypted information segments received by the information receiver by processing the received encrypted information segments with a session key used for encrypting the information segments in accordance with an algorithm utilized in a conditional access processes; and a conditional access controller in the information receiver for selectively enabling the decryptor to decrypt received information segments encrypted in accordance with the conditional access processes by providing to the decryptor cryptographic information for defining the algorithm utilized in the conditional access process for use by the decryptor to decrypt the received information segment encrypted in accordance with said algorithm. Algorithm-defining cryptographic information is downloaded from an information stream received by the information receiver.

Abstract: An access control processor for a conditional access system in which encrypted information segments provided by a plurality of information service providers are encrypted for transmission in accordance with different conditional access processes respectively utilizing different algorithms for encrypting the information segments.

Abstract: A system and method for scrambling and selectively descrambling television signals that are transmitted to subscribers' descramblers in a subscription television system. A working key signal is generated by processing an "initialization vector" signal in accordance with the DES algorithm upon the algorithm being keyed by either a common category key signal or some other key signal. A unique encryption keystream is generated by processing the initialization vector signal in accordance with the DES algorithm upon the algorithm being keyed by the working key signal. A television signal is scrambled in accordance with the unique encryption keystream to provide a scrambled television signal.