US Patent No. 9,124,929


Patent No. 9,124,929
Issue Date September 01, 2015
Title Secure Fast Channel Changing
Inventorship Erez Waisbard, Or-Yehuda (IL)
Anna Schnaiderman, Jerusalem (IL)
Assignee Cisco Technology Inc., San Jose, CA (US)

Claim of US Patent No. 9,124,929

1. A method for communication, comprising:
distributing over a communication network multiple channels of digital content, which are encrypted using different, channel-specific
control words; and

transmitting over the communication network, different, channel-specific entitlement control messages from which the control
words are derivable such that each of the different channel-specific control words is derivable from any of the different
channel-specific entitlement control messages by authorized receivers of the channels on the communication network, wherein:
(a) a first channel-specific control word for a first channel is derivable from a channel key for the first channel and a
master control word which is derivable from a first channel-specific entitlement control message for the first channel; and
(b) a second channel-specific control word for a second channel is derivable from a channel key for the second channel and
the master control word in the absence of the first channel-specific control word.