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.
Claims38
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;
- 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.
A system for enabling a device to read an encrypted file having encrypted content from a media, and to write an encrypted file having encrypted content to a media, the system comprising:
- a computing unit, and a system memory;
- interface means for receiving commands from the device;
- secure dynamic decryption means configured to:
- (a) copy an encrypted title key from the media to a memory of the device,
- (b) decrypt the encrypted title key,
- (c) decrypt a portion of encrypted content with the decrypted title key,
- (d) delete the decrypted title key, and
- (e) repeat a-d such until all of the content of the file has been decrypted, and wherein the decrypted title keys reside in and are accessible only to the secure means of the system.
A system that enables a device to decrypt a file having encrypted content on a secure medium, the system comprising:
- one or more user interface modules for receiving commands from the device;
- an applications programming interface for receiving the commands from the one or more user interface modules and managing the retrieval and storage of encrypted content from the secure medium;
- a security engine for decrypting the encrypted content and the one or more encrypted keys sent from the secure medium to a memory of the device, the decrypted keys used to decrypt the encrypted content, wherein
- the one or more keys are contained in an encrypted data segment, and
- the security engine (a) decrypts one or more of the keys, (b) decrypts a portion of the encrypted content using the one or more decrypted keys, and (c) deletes the one or more decrypted keys, and (d) repeats (a)-(c) until all portions of the content are decrypted.
The system of claim 20, wherein the security engine further comprises a random number generator, the generator utilizing two or more system timers to create the random number. 39. The system of claim 38, wherein the generator increases the natural frequency update of the timer ticks used to create the random number.
Dependencies are inferred from the claim text.