System, method, and device for playing back recorded audio, video or other content from non-volatile memory cards, compact disks or other media
AssigneeSanDisk Corporation
InventorsBahman Qawami, Farshid Sabet-Sharghi, Robert C. Chang
Life of this patent
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Abstract
A secure software system for a portable device or computer that provides a simple interface to the device or computer and that retrieves and dynamically decrypts keys and content from a secure media while minimizing exposure of the keys and eliminating the need for manufacturers of the device or computer to create a their own system to manage these complex processes.
Claims10
A method of accessing an encrypted track on a removable media with a device, the track comprising frames having content, the method comprising:
- authorizing the media by a process comprising:
- calculating a media key;
- and thereafter
- calculating a media unique key from the media key;
- and thereafter
- deleting the media key;
- and thereafter
- calculating a session key from the media unique key;
- and thereafter
- deleting the media unique key;
- and
- decrypting the track by a process comprising:
- (a) calculating a media unique key;
- and thereafter
- (b) decrypting a title key stored in the memory of the device with the media unique key;
- and thereafter
- (c) decrypting a group of frames;
- and thereafter
- (d) deleting the decrypted title key;
- (e) deleting the media unique key;
- and
- (f) repeating (a) through (e) until the entire track is completed.
A method of accessing an encrypted data file on a removable media with a device, the data file comprising frames having content, the method comprising:
- authorizing the media for a user session by a process comprising:
- calculating a media key;
- and thereafter
- calculating a media unique key from the media key;
- and thereafter
- deleting the media key;
- and thereafter
- calculating a session key from the media unique key;
- and thereafter
- deleting the media unique key;
- decrypting a doubly encrypted title key stored in the media with the session key to produce a singly encrypted title key;
- copying the singly encrypted title key from the media into a memory of the device;
- and
- decrypting the file by a process comprising:
- (a) calculating the media unique key;
- and thereafter
- (b) decrypting the title key stored in the memory of the device with the media unique key;
- and thereafter
- (c) decrypting a group of frames;
- and thereafter
- (d) deleting the decrypted title key;
- (e) deleting the media unique key;
- (f) repeating (a) through (e) until the entire file is completed.
Dependencies are inferred from the claim text.