Conditional access system, downloading of cryptographic information

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. Transmission of the cryptographic information for enabling the conditional access controller to enable the decryptor to decrypt a selected information segment may be requested by the conditional access controller and downloaded to the conditional access controller from an information stream received by the information receiver. Computer readable storage media are so configured as to cause the access control processor to perform its various functions.