DETECTION OF WATERMARKS IN SIGNALS

• US 20130129082A1
• Filed: 08/02/2011
• Published: 05/23/2013
• Est. Priority Date: 08/03/2010
• Status: Abandoned Application

• Current Assignee: Irdeto B.V. (MultiChoice Group Ltd.)
• Original Assignee: Irdeto B.V. (MultiChoice Group Ltd.)
• Inventors: Westerveld, Egbert
• Application Number:
  US13/810,891
• Publication Number:
  US 20130129082A1
• Time in Patent Office: Days
• US Class Current: 380/28
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 63/04 for providing a confidential data exchange among entities communicating through data packet networks
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/06 for supporting key management in a packet data network cryptographic mechanisms or cryptographic arrangements for key management H04L9/08
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/44008 involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

The invention provides for a method and a device for the detection of a watermark in a signal. A first signal is compared with two or more second signals. The second signal with the closest match contains the same watermark as in the first signal. Data indicative for the second signal with the closest match is output as an indication of the watermark in the first signal. The invention further provides for a head-end system that provides watermarked content from which the watermarks are detectable by the watermark detection device.

Claims

1. A method for detecting a watermark in a first signal, the method comprising:

receiving the first signal;

comparing the first signal with each of two or more second signals to determine a closest second signal, wherein each second signal comprises a unique watermark, and wherein the closest second signal is one of the two or more second signals having a closest match with the first signal; and

outputting data indicative for the closest second signal as an indication of the watermark in the first signal.

2. The method according to claim 1, further comprising:

receiving two or more third signals, wherein each third signal is encrypted with a unique key;

receiving decryption keys for each of the third signals; and

decrypting each of the third signals with the corresponding decryption key to obtain the two or more second signals.

3. The method according to claim 2, wherein each third signal comprises the unique watermark.

4. The method according to claim 1, further comprising:

receiving a third signal comprising two or more encrypted copies of a source signal, wherein each copy is encrypted with a unique key;

receiving decryption keys for each of the encrypted copies;

decrypting the third signal with each of the decryption keys, respectively, to obtain two or more decrypted third signals, wherein each decrypted third signal comprises decrypted copies of the source signal of which one decrypted copy is correctly decrypted and all other copies are incorrectly decrypted as a result of the decryption key used to decrypt the third signal corresponding to one of the encrypted copies only; and

inputting each of the decrypted third signals to an error handler configured for discarding the incorrectly decrypted copies and to thereby obtain the two or more second signals.

5. The method according to claim 4, wherein each encrypted copy of the source signal comprises the unique watermark.

6. The method according to claim 4, wherein a distortion in the second signal caused by the error handler defines the unique watermark.

7. The method according to claim 2, wherein at least one of the decrypted third signals comprises one or more bit errors deliberately introduced at a head-end system, the method further comprising processing the bit errors in an error handler or in a decoder, and wherein the unique watermark is formed by the processing of the bit error.

8. The method according to claim 1, wherein the steps are repeated for successive first signals, and wherein successively detected watermarks form a fingerprint.

18. A non-transitory computer readable medium having stored thereon computer executable instructions for implementing the method of claim 1.

19. The method according to claim 4, wherein at least one of the decrypted third signals comprises one or more bit errors deliberately introduced at a head-end system, the method further comprising processing the bit errors in an error handler or in a decoder, and wherein the unique watermark is formed by the processing of the bit error.

9. A detection device for detecting a watermark in a first signal, the detection device comprising:

a comparator configured to compare the first signal with each of two or more second signals to determine a closest second signal, wherein each second signal comprises a unique watermark, and wherein the closest second signal is one of the two or more second signals having a closest match with the first signal; and

a memory configured to store data indicative for the closest second signal as an indication of the watermark in the first signal.

10. The detection device according to claim 9, further comprising:

a receiver configured to receive two or more third signals, wherein each third signal is encrypted with a unique key;

a secure device communicatively connected to the receiver and configured to receive decryption keys for each of the third signals; and

a decryptor configured to decrypt each of the third signals with the corresponding decryption key to obtain the two or more second signals.

11. The detection device according to claim 10, wherein each third signal comprises the unique watermark.

12. The detection device according to claim 9, further comprising:

a receiver configured to receive a third signal comprising two or more encrypted copies of a source signal, wherein each copy is encrypted with a unique key;

a secure device communicatively connected to the receiver and configured to receive decryption keys for each of the encrypted copies;

a decryptor configured to decrypt the third signal with each of the decryption keys, respectively, to obtain two or more decrypted third signals, wherein each decrypted third signal comprises decrypted copies of the source signal of which one decrypted copy is correctly decrypted and all other copies are incorrectly decrypted as a result of the decryption key used to decrypt the third signal corresponding to one of the encrypted copies only; and

an error handler configured for discarding in each of the decrypted third signals the incorrectly decrypted copies and to thereby obtain the two or more second signals.

13. The detection device according to claim 12, wherein each encrypted copy of the source signal comprises the unique watermark.

14. The detection device according to claim 12, wherein a distortion in the second signal caused by the error handler defines the unique watermark.

15. The detection device according to claim 12, wherein at least one of the decrypted third signals comprises one or more bit errors deliberately introduced at a head-end system, the detection device further comprising an error handler or a decoder configured to process the bit errors, and wherein the unique watermark is formed by the processing of the bit error.

16. A head-end system for generating a signal from which a watermark is detectable, the head-end system comprising:

a duplicator configured to create two or more copies of at least a part of a source signal;

a bit error generator configured to introduce one or more bit errors in at least one of the two or more copies, wherein the bit errors are different for each copy; and

an encryptor configured to encrypt each copy with a unique encryption key, wherein the signal comprises at least one of the encrypted copies with bit errors.

17. (canceled)