Protection of audio or video data in a playback device

• US 8,256,005 B2
• Filed: 01/08/2007
• Issued: 08/28/2012
• Est. Priority Date: 01/08/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Lerouge, Julien, Fasoli, Gianpaolo, Farrugia, Augustin J.
• Primary Examiner(s): Vu, Kim
• Assistant Examiner(s): BEHESHTI SHIRAZI, SAYED ARESH
• Application Number:
  US11/651,300
• Publication Number:
  US 20080165961A1
• Time in Patent Office: 2,059 Days
• Field of Search: 726/26, 380/28, 713/168
• US Class Current: 726/26
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/41407 embedded in a portable device, e.g. video client on a mobile phone, PDA, laptop constructional details of equipment or arrangements specially adapted for portable computer application G06F1/1626; arrangements specially adapted for mobile receivers in broadcast systems H04H20/57
• CPC Class Codes: H04N 21/4325 by playing back content from the storage medium reproduction of recorded television signals H04N5/76; reproduction of recorded television signals H04N9/79
• CPC Class Codes: H04N 21/4398 involving reformatting operations of audio signals details of audio signal transcoding G10L19/173
• CPC Class Codes: H04N 21/4402 involving reformatting operations of video signals for household redistribution, storage or real-time display details of conversion of video standards at pixel level H04N7/01; video transcoding H04N19/40; adapting incoming signals to the display format of the display terminal G09G5/005; media handling at the source in data packet switching networks H04L65/764
• CPC Class Codes: H04N 21/4408 involving video stream encryption, e.g. re-encrypting a decrypted video stream for redistribution in a home network
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/163 by receiver means only
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

Method and apparatus to prevent hacking of encrypted audio or video content during playback. Hackers, using a debugging attachment or other tools, can illicitly access encrypted data in memory in a playback device when the data is decrypted during playback and momentarily stored in digital form. This hacking is defeated here by methodically “poisoning” the encrypted data so that it is no longer playable by a standard decoder. The poisoning involves deliberate alteration of certain bit values. On playback, the player invokes a special secure routine that provides correction of the poisoned bit values, for successful playback.

Claims

1. A method of playing secure video or audio data on a playback device, comprising the acts of:

receiving encrypted audio or video data from storage in the device, the audio or video data in addition to being encrypted having only predetermined portions poisoned according to logic wherein the encrypted audio or video data are parsable but not playable when decoded by a standard decoder, wherein the standard decoder conforms to the AAC or H.264 standard and the poisoning does not corrupt the structure of the poisoned portions;

decrypting the data;

parsing the decrypted data into portions;

in each decrypted and parsed portion, detecting the value of at least one predetermined bit location so as to determine whether that portion has been poisoned, wherein the value of the predetermined bit location is a reserved value according to the standard;

when the detected value does not match a predetermined value, indicating the absence of the poisoning, decoding the portion using the standard decoder, and playing the decoded portion;

when the detected value matches the predetermined value, indicating the presence of the poisoning in the decrypted and parsed portion, accessing a routine from a secure memory location in the playback device; and

decoding the poisoned portion using the routine and playing the decoded portion.

2. The method of claim 1, wherein each portion is a data frame or data packet.

3. The method of claim 1, wherein the predetermined bit location is in at least one of a section data block, a scale factor block, and a spectral data block.

4. The method of claim 1, wherein the values of a plurality of predetermined bit locations are detected to determine the presence of the poisoning.

5. The method of claim 1, wherein the routine is a modified AAC or H.264 decoder which decodes the portion.

6. The method of claim 1, wherein the routine accesses data from the secure memory location to substitute for the value in the predetermined bit location.

7. A non-transitory computer readable medium carrying computer code for carrying out the method of claim 1.

8. Computer enabled apparatus for carrying out the method of claim 1.

9. The method of claim 1, wherein the playback device is a computer or audio or video player.

10. The method of claim 1, wherein the values of at least one predetermined bit location are not detected.

32. The method of claim 1, wherein the predetermined bit location is in a data block which is specified by the standard as being a required data block.

33. The method of claim 1, wherein the standard is the AAC standard and each portion is a data packet having a plurality of data blocks including a section data block, and the predetermined bit location is in the section data block only if a current window of the audio data is at least of a predetermined length.

11. Apparatus for playing secure video or audio data, comprising:

storage for storing audio or video data in encrypted form, the audio or video data in addition to being encrypted having only predetermined portions poisoned according to logic wherein the encrypted audio or video data are parsable but not playable when decoded by a standard decoder, wherein the standard decoder conforms to the AAC or H.264 standard and the poisoning does not corrupt the structure of the poisoned portions;

a decryptor coupled to the storage to decrypt the data;

a parser coupled to the decryptor to parse the decrypted data into portions;

a logic element coupled to the parser to detect the value of at least one predetermined bit location in each decrypted and parsed portion so as to determine whether that portion has been poisoned, wherein the value of the predetermined bit location is a reserved and normally unused value according to the standard, and to determine whether the detected value matches a predetermined value indicating the presence of the poisoning in the decrypted and parsed portion, and accessing a routine from a secure memory location in the apparatus in event of a match;

wherein the poisoned portion is decoded for play using the routine, and

wherein the portion is otherwise decoded for play in the absence of a match, indicating the absence of the poisoning, by the standard decoder which is coupled to the logic element.

12. The apparatus of claim 11, wherein each portion is a data frame or data packet.

13. The apparatus of claim 11, wherein the predetermined bit location is in at least one of a section data block, a scale factor block, and a spectral data block.

14. The apparatus of claim 11, wherein the values of a plurality of predetermined bit locations are detected to determine the presence of the poisoning.

15. The apparatus of claim 11, wherein the routine is a modified AAC or H.264 decoder which decodes the portion.

16. The apparatus of claim 11, wherein the routine accesses data from the secure memory location to substitute for the value in the predetermined bit location.

17. A non-transitory computer readable medium carrying computer code for carrying out the apparatus of claim 11.

18. The apparatus of claim 11, wherein the apparatus is a computer or audio or video player.

19. A method of providing secure audio or video data for a playback device, comprising the acts of:

receiving encrypted audio or video data from a source external to the playback device;

decrypting the data;

parsing the decrypted data into portions according to the AAC or H.264 standard;

in each portion, identifying according to a predetermined criteria whether a value of a predetermined bit location is to be modified wherein the portion is poisoned;

when the value is to be modified, modifying the value of the predetermined bit location according to logic, wherein the poisoned portions are parsable but not playable when decoded by a decoder conforming to the standard and the poisoning does not corrupt the structure of the poisoned portions and the value of the predetermined bit location is a reserved value according to the standard;

reassembling the portion with the modified value;

encoding the portion;

re-encrypting encoded portion; and

storing the re-encrypted portion in memory in the device for later playback.

20. The method of claim 19, wherein the encoding is according to the AAC or H.264 standards.

21. The method of claim 19, wherein each portion is a data frame or data packet.

22. The method of claim 19, wherein the predetermined bit location is in at least one of a section data block, a scale factor block, and a spectral data block.

23. The method of claim 19, wherein the values of a plurality of predetermined bit locations are detected.

24. The method of claim 20, wherein the matching value of the predetermined bit location is a reserved value according to the standard.

25. The method of claim 19, wherein the routine decodes the portion.

26. The method of claim 19, wherein the routine accesses data from a secure memory location to substitute for the value in the predetermined bit location.

27. A non-transitory computer readable medium carrying computer code for carrying out the method of claim 19.

28. Computer enabled apparatus for carrying out the method of claim 19.

29. The method of claim 19, wherein the playback device is a computer or audio or video player.

30. Apparatus for playing secure video or audio data, comprising:

a port adapted to receive encrypted audio or video data from a source external to the playback apparatus;

a decryptor coupled to the port for decrypting the received data;

a parser coupled to the decryptor for parsing the decrypted data into portions according to the AAC or H.264 standard;

a logic element coupled to the parser and which identifies, according to a predetermined criterion, whether a value of a predetermined bit location in each portion is to be modified wherein the portion is poisoned;

wherein the value of the predetermined bit location is a reserved value according to the standard;

a secure memory location coupled to the logic element;

wherein the logic element modifies the value of the predetermined bit location according to a routine stored in the secure memory location, and reassembles the portion, wherein the poisoned portions are parsable but not playable when decoded by a decoder conforming to the standard and the poisoning does not corrupt the structure of the poisoned portions and the value of the predetermined bit location is a reserved value according to the standard;

an encoder coupled to the logic element and which encodes the poisoned portion;

an encryptor coupled to the encoder and which re-encrypts the encoded poisoned portion; and

storage coupled to the encryptor and which stores the re-encrypted poisoned portion for later playback.

31. Apparatus for video or audio play, comprising:

an input portion including;

a port adapted to receive encrypted audio or video data from a source external to the playback apparatus;

a decryptor coupled to the port for decrypting the received data;

a parser coupled to the decryptor for parsing the decrypted data into portions according to the AAC or H.264 standard;

a logic element coupled to the parser and which identifies, according to a predetermined criterion, whether a value of a predetermined bit location in each portion is to be modified wherein the portion is poisoned;

wherein the value of the predetermined bit location is a reserved value according to the standard;

a secure memory location coupled to the logic element, wherein the original value of the predetermined bit location is stored in the secure memory location; and

wherein the logic element modifies the value of the predetermined bit location, and reassembles the portion, wherein the poisoned portions are parsable but not playable when decoded by a decoder conforming to the standard and the poisoning does not corrupt the structure of the poisoned portions and the value of the predetermined bit location is a reserved value according to the standard;

an encoder coupled to the logic element and which encodes the poisoned portion;

an encryptor coupled to the encoder and which re-encrypts the encoded poisoned portion; and

storage coupled to the encryptor and which stores the re-encrypted poisoned portion for later playback;

and an output portion comprising;

a logic element coupled to the parser to detect the value of the at least one predetermined bit location in each portion, and to determine whether the value of the at least one predetermined bit location matches a predetermined value indicating the presence of the poisoning, and accessing a routine from a secure memory location in the apparatus in event of a match;

wherein the portion is decoded for play using the routine, and PS wherein when the detected value does not match the predetermined value, indicating the absence of the poisoning, the portion is not decoded for play.