PIRACY-PROTECTED METHOD FOR DISTRIBUTING NUMERIC CONTENT BY ANTICIPATORY TRANSMISSION, RELEVANT TRANSMITTING DEVICE, AND PORTABLE RECEIVING DEVICE

摘要

FIELD: ciphering key transmission methods and systems. ^ SUBSTANCE: according to proposed method same information Kc is afforded for more than one receivers 1 pertaining to receiver group G; each receiver saves SAi information unambiguously assigned to the latter. Kc information is determined by expression Kc = f(K,biSAi), where f is desired function; K is information common to all receivers; b1 is information different for each receiver and for each value of information K. Each receiver is given access to information b1 prior to submitting information Kc. Information K is transferred to all receivers directly prior to submitting information Kc so that each receiver can calculate the latter using mentioned expression. ^ EFFECT: simplified design and enhanced response of system to piratical cards. ^ 13 cl, 2 dwg