Nagravision S.a.

Nagracard S.a.

Serge Gaumain

Henri Kudelski

A method is used to restore the security of a secure assembly such as a chip card, after the contents of its second memory zone have been read by a third party. The method is for generating a security key implemented by a secure module comprising a central unit, a first conditional access memory zone and at least one second memory zone containing all or part of the user program. The method includes reading of all or part of the second memory zone, and generation of at least one root key based on all or part of the second zone data and on at least one item of secret information stored in the first memory zone.

Generating a root key for decryption of a transmission key allowing secure communications

The security modules used in pay television and in other applications are intended to develop and thus to be replaced. In order to promote the replacement of a previous generation by a new one, the method according to the invention consists in sending by a control center in the data stream a replacement prompt command including the minimal characteristics of the security module of the new generation, establishing the characteristics of the security module being used, and comparing with the minimal characteristics defined by the received command, and according to the results of this comparison, prompting the user to replace the security module.

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Yverdon, Switzerland

Serge Gaumain