Nagracard S.a.

Cédric Groux

Henri Kudelski

Rached Ksontini

A method is for protecting an encrypted content, by use of at least one encryption key. The method includes generation of a temporary encryption key, encryption by the temporary key of a value allowing the determination of the encryption keys of the content, transmission of the encrypted value to a multimedia unit, and encryption and transmission of at least two cryptograms including the temporary key encrypted by an authorization key. The first cryptogram is encrypted by a first authorization key pertaining to a first security module and the second cryptogram is encrypted by a second authorization key pertaining to a group of security modules whose first security module is excluded.

Method for securing a ciphered content transmitted by a broadcaster

A method for storing of a plurality of data blocks in a digital rewritable memory of semiconductors controlled by a memory manager and includes the steps of: randomly determining an available area; and storing the data block in the area determined in the determining step. This method of data storage is preferably applied to chip cards and to similar electronic modules. It prevents the reproduction of the functionalities of the card after an analysis of the contents of the memory. Furthermore, it assures a better distribution of the wearing of the memory.

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Chexbres, Switzerland

Cédric Groux