System for secure decryption of streaming media using selective decryption of header information and decryption of reassembled content

• US 20040139335A1
• Filed: 01/14/2003
• Published: 07/15/2004
• Est. Priority Date: 01/14/2003
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Peterka, Petr, Diamand, Joseph
• Granted Patent: US 7,251,328 B2
• Time in Patent Office: Days
• US Class Current: 713/189
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/4334 Recording operations recording of a television signal H04N5/76; arrangements for recording or accumulating broadcast information or broadcast-related information H04H60/27
• CPC Class Codes: H04N 21/44055 by partially decrypting, e.g. decrypting a video stream that has been partially encrypted
• CPC Class Codes: H04N 21/6125 involving transmission via Internet transmission by internet of broadcast information H04H60/82
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/162 Authorising the user terminal, e.g. by paying; Registering the use of a subscription channel, e.g. billing
• CPC Class Codes: H04N 9/8042 involving data reduction

Abstract

A system provides improved security in a streaming media decoder includes decryption of encoded media information at the media layer, within a decoder component of a playback device. A content source, such as an MPEG-4 media stream from a network, or a file on a local storage device, etc. that contain packetized content, and supplies encrypted and encoded media information. For example, digital sound and image information can be conveyed for presentation. A reassembler component is used to initiate decryption of a nominal amount of information needed to perform further processing at the QuickTime player. Encrypted access units are sent from the reassembler to the decoder, where the decoder causes decryption of the access unit information. This approach prevents decrypted, encoded information from being transferred from the reassembler to the decoder. Such decrypted and encoded information is especially susceptible to copying. Instead, the information transferred from the reassembler to the decoder is largely still encrypted. In a preferred embodiment, an Internet Protocol rights management system (IPRM) is used to perform the decryption processing. The reassembler makes requests of the IPRM process to open a decryption session and decrypt selected packets to identify the window rendering size. The decoder makes requests of the IPRM process to decrypt access units within the same decryption session and to close the decryption session. Because content is encrypted on packet boundaries, and when called upon by the decoder, the IPRM component must recreate the packet boundaries from the access unit before decryption is possible. The IPRM system component is able to do so because the encrypted packets contain an IPRM header that is used by the IPRM system to calculate the packet length. After decrypting all the packets, the IPRM system component reconstructs the decrypted access unit and returns decrypted content to the decoder.

Claims

1. An apparatus for decrypting encrypted, encoded digital media information for presentation, the apparatus comprising

a reassembler for receiving encrypted packets from a packet source, wherein a plurality of the packets include encoded digital media information;

a decoder coupled to the reassembler for decoding the encoded digital media information; and

a decryption resource coupled to the reassembler and to the decoder for decrypting encrypted information.

2. The apparatus of claim 1, wherein a first packet includes first information describing the size of a rendering window, the apparatus further comprising

the reassembler including circuitry for initiating decrypting of the first information to obtain the size of the rendering window.

3. The apparatus of claim 2, wherein QuickTime player required information is included in the first packet.

4. The apparatus of claim 3, wherein MPEG-4 format is used to encode the digital media information.

5. The apparatus of claim 4, wherein the size of the rendering window is included in a VOL header of the MPEG-4 format.

6. The apparatus of claim 1, wherein the digital media information includes streaming media.

7. A method for decrypting streaming media information, the method comprising

decrypting at least a portion of the streaming media information in a media layer.

8. A method for decrypting media information in a presentation device, wherein the presentation device includes a reassembler coupled to a decoder, the method comprising

decrypting a first portion of the media information at the reassembler;

and

decrypting a second portion of the media information at the decoder.

9. The method of claim 8, wherein the step of decrypting a second portion includes a substep of

re-decrypting content that was already decrypted by the reassembler and forwarded in an original encrypted state to the decoder.

10. The method of claim 9, wherein at least a portion of the media information is in MPEG-4 video access units format, the method further comprising

passing an encrypted access unit from the reassembler to the decoder;

and

using the decoder to decrypt the encrypted access unit.

11. The method of claim 10, further comprising

decrypting a first portion of the media information in the reassembler to obtain a size of a rendering window to be used for playback of the media information.

12. The method of claim 11, wherein the first portion of the media information is included in an MPEG-4 VOL header.

13. The method of claim 12, wherein the media information is delivered as video-on-demand content, the method further comprising

obtaining the VOL header from a first packet.

14. The method of claim 12, wherein the media information is obtained as a live broadcast, the method further comprising

decrypting packets in the reassembler until an I-frame containing the VOL header is obtained.

15. The method of claim 9, wherein information is decrypted at the reassembler until initial header information is obtained.

16. The method of claim 9, further comprising

using an IPRM process to perform decryption, wherein the IPRM process is in communication with the reassembler and the decoder.

17. The method of claim 9, further comprising

using the reassembler to initiate a decryption session with the IPRM process.

18. The method of claim 17, further comprising

using the decoder to close the decryption session with the IPRM process.

19. The method of claim 18, further comprising

using the reassembler to request decryption of a packet containing volume header information from the IPRM process.

20. The method of claim 19, further comprising

using the decoder to request decryption of access unit information.

21. The method of claim 20, wherein the access unit information is included into a plurality of packets.

22. The method of claim 20, wherein access unit information sent to the IPRM process does not include packet header information that delineates packet boundaries.

23. The method of claim 20, further comprising

decomposing an access unit sent to the IPRM process into packet payload boundaries used during encryption;

and

decrypting the packets resulting from the step of decomposing.

24. The method of claim 23, further comprising

passing the length of an access unit to the IPRM process.

25. The method of claim 23, further comprising

using the IPRM system to extract IPRM header information from the access unit to identify the length of a packet.

26. The method of claim 25, further comprising

using the identified length of a packet to determine the starting point of a next packet payload boundary.

27. The method of claim 20, wherein the IPRM process is used to decrypt packets and reassemble the decrypted packets into an access unit.

28. The method of claim 20, wherein the IPRM process is used to return a decrypted access unit to the decoder.