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:
Feb. 23, 2010
Filed:
Jan. 24, 2001
André Kudelski, Lutry, CH;
Marco Sasselli, Chardonne, CH;
André Kudelski, Lutry, CH;
Marco Sasselli, Chardonne, CH;
NagraCard S.A., Cheseaux-sur-Lausanne, CH;
Abstract
At the moment of the diffusion of Pay-TV with multi-channel signals, each channel is associated to authorization messages (ECM) which allow to decrypt this channel according to the rights of the subscriber. When changing channel, a very short time is accepted before one has determined these new rights in relation with the new channel. The heavy encrypting algorithms are thus excluded. To avoid this drawback, to decrypt a channel, a system is proposed using the combination of the authorization information for a channel (ECM), and thus encrypted by a fast algorithm, with authorization information (MECM) for a group of channels. These latter are encrypted by a high security algorithm and are thus slower to decrypt.