The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 28, 2017
Filed:
Mar. 07, 2011
Andre Kudelski, Lutry, CH;
Andre Kudelski, Lutry, CH;
NAGRAVISION S.A., Cheseaux-sur-Lausanne, CH;
Abstract
A method for controlling access to a plurality of channels by a unit comprising a security module, each channel being encrypted by a specific control word and having a channel identifier, this method comprising the steps of: tuning to a first channel having first channel identifier and receiving first messages containing a first control word; decrypting the first messages and using the first control word; storing the first control word and the first channel identifier; tuning to a second channel having second channel identifier; calculating the second control word by: calculating a root control word with an inverse cryptographic function Fusing the first control word and the first channel identifier; calculating the second control word with the cryptographic function F using the root control word and the second channel identifier; and using the second control word to access the second channel.