Patent ID: 7940930

Claim:
A system for scrambling/descrambling packets of a stream of content, each of the packets having a must stay clear (MSC) section which is always kept in the clear, the system comprising physical computing machinery including: an input handler including: a receiving module to receive the stream; and mask module to create, for each of the packets, a data mask which includes all data of the MSC section except for at least one bit of data of the MSC section; and a scrambling/descrambling device operationally associated with the input handler, the scrambling/descrambling device including: a receiving module to receive the data mask for each of the packets from the input handler; and an Initial Value module to determine an Initial Value for each of the packets as a function of the data mask of one of the packets being processed such that the Initial Value is not a function of the at least one bit of data of the MSC section of the one packet being processed, the scrambling/descrambling device being adapted to at least one of scramble and descramble the packets based on the Initial Value and a Control Word.