Patent ID: 8458493
Filing Date: 2013-06-04
Classification: G11B

Abstract:
1. A method of reading, by a reader, digital data ciphered using a symmetrical algorithm with a data ciphering key on a physical medium, comprising: providing a physical medium for storage of the digital data, the physical medium equipped with a calculation means; and, on first reading from the physical medium: transferring to the calculation means, by an asymmetrical ciphering process, a user key; calculating, in said calculation means of the medium and by a symmetrical algorithm with the user key, a ciphered key of said data ciphering key; invalidating, on reception of the user key by the calculation means, the asymmetrical ciphering process of the calculation means so that the calculation means is not able to reset the user key which was received by the calculation means from the reader, so that the data ciphering key with which the digital data on the physical medium have been coded can then only be transmitted in a symmetrical mode; and reading decoded digital data from the physical medium while the asymmetrical ciphering process is deactivated.