Device for and a Method of Processing an Encrypted Data Stream in a Cryptographic System

• US 20080212774A1
• Filed: 04/25/2006
• Published: 09/04/2008
• Est. Priority Date: 04/26/2005
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Moors, Eric, Manders, Roland, Rijckaert, Albert
• Application Number:
  US11/912,320
• Publication Number:
  US 20080212774A1
• Time in Patent Office: Days
• US Class Current: 380/201
• CPC Class Codes: H04N 21/2387 Stream processing in response to a playback request from an end-user, e.g. for trick-play
• 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 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/6587 Control parameters, e.g. trick play commands, viewpoint selection
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/167 Systems rendering the television signal unintelligible and subsequently intelligible
• CPC Class Codes: H04N 9/8042 involving data reduction
• CPC Class Codes: H04N 9/8205 involving the multiplexing of an additional signal and the colour video signal

Abstract

A device (3200) for processing an encrypted data stream (3201) in a cryptographic system, in which decryption data (3204) are provided for decrypting each segment (3202) of the encrypted data stream (3201) for reproduction of the decrypted data stream, wherein the device (3200) comprises a first determining unit (3209) for determining, in case of switching from a first reproduction mode (1501) of reproducing the data stream (3201) to a second reproduction mode (1502) of reproducing the data stream (3201), a current position of reproduction within the data stream, and a second determining unit (3210) for determining a starting position for starting reproduction in the second reproduction mode (1502) based on the determined current position.

Claims

1-18. -18. (canceled)

19. A device (3200) for processing an encrypted data stream (3201) in a cryptographic system, in which decryption data (3204) are provided for decrypting each segment (3202) of the encrypted data stream (3201) for reproduction of the decrypted data stream,

wherein the device (3200) comprises

a first determining unit (3209) for determining, in case of switching from a first reproduction mode (1501) of reproducing the data stream (3201) to a second reproduction mode (1502) of reproducing the data stream (3201), a current position of reproduction within the data stream (3201);

a second determining unit (3210) for determining a starting position for starting reproduction in the second reproduction mode (1502) based on the determined current position, and wherein the second determining unit (3210) is adapted for determining a starting position for starting reproduction in the second reproduction mode (1502) based on a delay (2703) with which decryption data (3204) are provided in the cryptographic system.

20. The device (3200) according to claim 19,

wherein the second determining unit (3210) is adapted for determining a starting position for starting reproduction in the second reproduction mode (1502) based on characteristics of the cryptographic system.

21. The device (3200) according to claim 19,

wherein the second determining unit (3210) is adapted for determining a starting position for starting reproduction in the second reproduction mode (1502) based on a delay (2703) with which decryption data (3204) for decrypting a succeeding segment are provided in the cryptographic system.

22. The device (3200) according to claim 19,

wherein the second determining unit (3210) is adapted for determining a beginning or an end of a segment preceding or succeeding the currently reproduced segment as a starting position for starting reproduction in the second reproduction mode (1502).

23. The device (3200) according to claim 19,

wherein the second determining unit (3210) is adapted to determine the starting position based on a speed of reproduction of the data stream (3201) according to the second reproduction mode (1502).

24. The device (3200) according to claim 19,

wherein the second determining unit (3210) is adapted to determine the starting position in such a manner that a segment of the encrypted data stream (3201) which is to be reproduced next after a currently reproduced segment of the data stream is decryptable by means of the corresponding decryption data (3204) decrypted at a time before the reproduction of the currently reproduced segment of the data stream (3201) is finished.

25. The device (3200) according to claim 19,

adapted to process an encrypted data stream (3201) of video data or audio data.

26. The device (3200) according to claim 19,

adapted to process an encrypted data stream (3201) of digital data.

27. The device (3200) according to claim 19,

wherein the first reproduction mode is a normal reproduction mode (1501).

28. The device (3200) according to claim 19,

wherein the second reproduction mode is a trick-play reproduction mode (1502).

29. The device (3200) according to claim 28,

wherein the trick-play reproduction mode (1502) is one of the group consisting of a fast forward reproduction mode (2600), a fast reverse reproduction mode (2601), a slow motion reproduction mode, a freeze frame reproduction mode, an instant replay reproduction mode, and a reverse reproduction mode.

30. The device (3200) according to claim 19,

comprising a generation unit (3211) adapted to generate a decrypted data stream or an encrypted data stream for reproduction in the second reproduction mode (1502) from the starting position onwards.

31. The device (3200) according to claim 19,

adapted to process an encrypted MPEG2 data stream.

32. The device (3200) according to claim 19,

realized as at least one of the group consisting of a digital video recording device and a network-enabled device and a conditional access system and a portable audio player and a portable video player and a mobile phone and a DVD player and a CD player a harddisk-based media player and an internet radio device and a public entertainment device and an MP3 player.

33. A method of processing an encrypted data stream (3201) in a cryptographic system, in which decryption data (3204) are provided for decrypting each segment (3202) of the encrypted data stream (3201) for reproduction of the decrypted data stream,

wherein the method comprises the steps of

in case of switching from a first reproduction mode (1501) of reproducing the data stream (3201) to a second reproduction mode (1502) of reproducing the data stream (3201), determining a current position of reproduction within the data stream (3201);

determining a starting position for starting reproduction in the second reproduction mode (1502) based on the determined current position and a delay (2703) with which decryption data (3204) are provided in the cryptographic system.

34. A computer-readable medium, in which a computer program of processing an encrypted data stream (3201) in a cryptographic system, in which decryption data (3204) are provided for decrypting each segment (3202) of the encrypted data stream (3201) for reproduction of the decrypted data stream (3201), is stored, which computer program, when being executed by a processor, is adapted to control or carry out the following method steps:

in case of switching from a first reproduction mode (1501) of reproducing the data stream (3201) to a second reproduction mode (1502) of reproducing the data stream, determining a current position of reproduction within the data stream (3201);

determining a starting position for starting reproduction in the second reproduction mode (1502) based on the determined current position and a delay (2703) with which decryption data (3204) are provided in the cryptographic system.

35. A program element of processing an encrypted data stream (3201) in a cryptographic system, in which decryption data (3204) are provided for decrypting each segment (3202) of the encrypted data stream (3201) for reproduction of the decrypted data stream, which program element, when being executed by a processor, is adapted to control or carry out the method steps of:

in case of switching from a first reproduction mode (1501) of reproducing the data stream (3201) to a second reproduction mode (1502) of reproducing the data stream (3201), determining a current position of reproduction within the data stream (3201);

determining a starting position for starting reproduction in the second reproduction mode (1502) based on the determined current position and a delay (2703) with which decryption data (3204) are provided in the cryptographic system.