New patents are issued Tuesdays by the USPTO. Assigned to Philips, the first of today's patents addresses the use of watermarking to carry copy protection information. Assigned to IBM, the second patent describes techniques for key distribution in a conditional access system.
7,310,819, "Processing copy protection signals," assigned to Philips.
A method and device if or recording an information signal with first copy protection information to a storage medium includes recording according to first copy rules identified by the first copy protection information. The first copy protection information identifying the first copy rules is detected, and at least second copy protection information is recorded according to the detected first copy rules. The first and second copy protection information identify a legality message to be interpreted by reader. Screening information is recorded in a safe way on the storage medium to identify that the first copy protection message has been read.
7,296,159, "Key distribution in a conditional access system," assigned to IBM.
Methods and apparatus for key distribution in a conditional access system, assuming that the set of all user nodes which the system can accommodate is a complete set, and a subset is composed of all user nodes or part of user nodes. One method comprises: decomposing said subset into at least one secondary subset; assigning a different user key to each secondary subset, each said user key being transmitted to all users in a corresponding secondary subset; encrypting an entitlement key by using each said user key so as to generate a cipher text corresponding to each said secondary subset; and combining said cipher text to generate a media key control block and transmitting said media key control block to all users in said subset. Since a classification method of a binary tree and a multiple tree is used, the invention can save a lot of network resources.