Copy protection method for digital media

• US 7,506,376 B2
• Filed: 02/04/2002
• Issued: 03/17/2009
• Est. Priority Date: 02/05/2001
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kuzmich, Vsevolod M., Belenko, Vyacheslav S.
• Primary Examiner(s): Brown; Christopher J
• Application Number:
  US10/061,364
• Publication Number:
  US 20020114458A1
• Time in Patent Office: 2,598 Days
• Field of Search: 713/193, 713/176, 713/165, 713/170, 726/26, 726/27
• US Class Current: 726/26
• CPC Class Codes: H04N 21/23895 involving multiplex stream encryption
• CPC Class Codes: H04N 21/835 Generation of protective data, e.g. certificates protecting software against unauthorised usage in a vending or licensing environment G06F21/10
• CPC Class Codes: H04N 21/8352 involving content or source identification data, e.g. Unique Material Identifier [UMID]
• 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 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

A method of digital media copy protection is disclosed. The method of the present invention is applicable to any type of digital media data and makes no assumptions on any specific media properties. The method includes a process of protecting digital media data with a public key using a hybrid cryptographic technique, a process of watermarking the media data, and an output device compliance testing process through an authenticated handshake protocol. Because of the media data protection with the hybrid cryptographic technique, a non-compliant playing device is not able to play or read a protected media data set. The output device compliance testing protocol is used to prevent the media signal from being copied to any non-compliant device. These features of the present invention are used to reduce the possibility of making any illegal copies on any nonstandard equipment. In addition, the data watermarking is used to modify the played and recorded media signals, to keep track of the identification information of the related devices for detecting any illegal copy maker, and to separate legal media data sets from the illegal data sets.

Claims

1. A copy protection method for digital media, the method comprising the steps of:

(a) encrypting an original media data set with a media key having a symmetric algorithm and encrypting said media key with a public key of a compliant device;

(b) delivering said encrypted media data set and said encrypted media key to a compliant playing device, wherein said original media data set includes an owner watermark containing an owner identification and owner copy-control information for the media data set;

(c) decrypting said delivered media key with a private key of said playing device;

(d) decrypting said delivered media data set with said decrypted media key;

(e) adding a player watermark to said decrypted media data set if said decrypted data set is not marked with at least “

free copy”

, said player watermark containing a player identification of said playing device and player copy-control information, wherein said player copy-control information is derived from said owner copy-control information; and

(f) if passing said watermark-added media set to a recording device. encrypting said watermark-added media data set with said decrypted media key, encrypting said decrypted media key with said public key of said compliant device, and passing said encrypted watermark added media data set and said encrypted media key to said recording device without a compliance test, and (e) if passing said-watermark-added media data to a displaying device, performing a compliance test with said displaying device and if said compliance test is successful, passing said watermark-added media data set and said decrypted media key to said displaying device without encrypting.

2. The method of claim 1, wherein said public key corresponds to an asymmetric algorithm.

3. The method of claim 1, wherein said player copy-control information is set to “

for display only”

if said media data set is passed to said displaying device.

4. A copy protection method for digital media, the method comprising:

(a) receiving an encrypted media data set, a control information, and an encrypted media key, wherein the encrypted media data is generated by an original media data set with a media key and the encrypted media key is generated by encrypting said media key with a public key of a compliant device, wherein the control information includes owner identification of media data set and a copy control information to indicate whether a copy of the media data set permitted;

(b) decrypting said received media key with a private key of said compliant device, and decrypting said received media data set with said decrypted media key;

(c) adding a device information to the media data set to indicate an origin of the media data set, said device information including a device identification and copy-control information, wherein said copy-control information is derived from said owner copy-control information; and

(d) outputting said media data set to which the device information is added, to an external device, wherein said outputting comprises (e) if said external device is a recording device, encrypting said media data set with said decrypted media key and outputting without a compliance test, and (f) if said external device is a displaying device, performing a compliance test with said displaying device and outputting without encrypting.

5. The method of claim 4, wherein said compliance test is performed through an authentication process between said compliant device and said displaying device wherein said step (d) outputs said media data set to which the device information is added only if said authentication is successful.

6. The method of claim 4, wherein said player copy control information is set to “

for display only”

if said media data set is passed to said displaying device.

7. A copy protection system for digital media, the system comprising:

a receiving unit configured for receiving an encrypted media data set, a control information, and an encrypted media key, wherein the encrypted media data is generated by an original media data set with a media key and the encrypted media key is generated by encrypting said media key with a public key of a compliant device, wherein the control information includes owner identification of media data set and a copy control information to indicate whether a copy of the media data set is permitted;

a decrypting unit configured for decrypting said received media key with a private key of said compliant device, and decrypting said received media data set with said decrypted media key;

a watermark adder configured for adding a device information to the media data set to indicate an origin of the media data set, said device information including a device identification and copy-control information, wherein said copy-control information is derived from said owner copy-control information; and

an output unit configured for outputting said media data set to which the device information is added, to an external device, wherein said output unit encrypts said media data set with said decrypted media key and outputs without a compliance test if said external device is a recording device, while said output unit performs a compliance test with said displaying device and outputs without encrypting if said external device is a displaying device.

8. The system of claim 7, wherein said compliance test is performed through an authentication process between said compliant device and said displaying device, wherein said output unit is configured for outputting said media data set to which the device information is added only if said authentication is successful.

9. The system of claim 7, wherein said player copy-control information is set to “

for display only”

if said media data set is passed to said displaying device.