Aparelho para o processamento de fluxo de dados em um sistema de recepção a partir de um canal de comunicações um fluxo de dados digitais de um sinal de vídeo incluindo informações criptografadas e informações não criptografadas

摘要

A receiver of satellite-broadcast signals including high definition television signals includes apparatus (12-26) for decrypting encrypted signals. When unencrypted "plaintext" signal information which is not to be decrypted is received, the plaintext information is applied to the decrypting apparatus. Normal decrypting operation is modified so that the input plaintext information appears as unaltered plaintext information at the output of the decrypting apparatus. A bit selection network (628; S1, ... S8) associated with a decipher function (f(R,K)) of the decryption apparatus employs a combinational logic network (18, 628) rather than Look up Tables.