Xin Wang

US Patent:

6519700, Feb 11, 2003

Filed:

Oct 23, 1998

Appl. No.:

09/178529

Inventors:

Prasad Ram - Manhattan Beach CA
Thanh T. Ta - Huntington Beach CA
Xin Wang - Los Angeles CA

Assignee:

Contentguard Holdings, Inc. - Wilmington DE

International Classification:

C06F 1216

US Classification:

713193, 713160, 380 45, 380201, 705 51, 705 57

Abstract:

A system and method for the secure distribution of electronic documents reduces the likelihood of unauthorized reproduction and redistribution by either authorized or unauthorized recipients. A self-protecting document (SPD) contains an encrypted document as well as a secure set of permissions and the software necessary to process the document; full decryption of the document is performed as late as possible so as to minimize the possibility of intercepting the document before it has been fully rendered to screen or to paper.

US Patent:

6696854, Feb 24, 2004

Filed:

Sep 17, 2001

Appl. No.:

09/956374

Inventors:

Afshin Momtaz - Irvine CA
Xin Wang - Irvine CA
Jun Cao - Irvine CA
Armond Hairapetian - Glendale CA
David Chung - Newport Beach CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

G11C 700

US Classification:

326 37, 326 40, 365221

Abstract:

Methods and circuitry for implementing high speed first-in first-out (FIFO) structures. In one embodiment, a FIFO is disclosed that allows the frequency of one clock, e. g. , the write clock, to be different than (e. g. , half) that of the other (read) clock. In another embodiment a FIFO is presented that can be set and/or reset asynchronously. Other embodiments are disclosed wherein the read and write pointers are effectively monitored to ensure proper timing relationship, to detect loss of clock as well as to detect other abnormal FIFO conditions.

US Patent:

6760353, Jul 6, 2004

Filed:

Jul 30, 2002

Appl. No.:

10/209293

Inventors:

Xin Wang - Irvine CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H01S 300

US Classification:

372 3802, 372 3807

Abstract:

Driver circuits of the present invention provide current to drive laser diodes. The output current of the driver circuit includes a data signal and a low frequency tone signal. The low frequency tone signal is within the bandwidth of a power control feedback loop. The tone signal introduces low frequency noise into the output signal of the driver circuit. The low frequency noise causes jitter at the zero crossing points of the driver circuit output signal. A laser driver circuit of the present invention provides a compensation current to a laser diode. The compensation current is out of phase with the tone signal. The compensation current eliminates the low frequency noise in the output signal of the laser driver circuit.

US Patent:

6763464, Jul 13, 2004

Filed:

Jul 18, 2002

Appl. No.:

10/196953

Inventors:

Xin Wang - Los Angeles CA
Thanh T. Ta - Huntington Beach CA
Prasad Ram - Manhattan Beach CA

Assignee:

ContentGuard Holdings, Inc. - Wilmington DE

International Classification:

G06F 1216

US Classification:

713193, 713160, 380 45, 380201, 705 51, 705 57

Abstract:

A system and method for the secure distribution of electronic documents reduces the likelihood of unauthorized reproduction and redistribution by either authorized or unauthorized recipients. A self-protecting document (SPD) contains an encrypted document as well as a secure set of permissions and the software necessary to process the document; full decryption of the document is performed as late as possible so as to minimize the possibility of intercepting the document before it has been fully rendered to screen or to paper.

US Patent:

6859533, Feb 22, 2005

Filed:

Dec 21, 1999

Appl. No.:

09/469487

Inventors:

Xin Wang - Los Angeles CA, US
Thanh T. Ta - Huntington Beach CA, US

Assignee:

ContentGuard Holdings, Inc. - Wilmington DE

International Classification:

H04L009/28

US Classification:

380 28, 380259

Abstract:

Methods for transferring among key holders in encoding and cryptographic systems the right to decode and decrypt messages in a way that does not explicitly reveal decoding and decrypting keys used and the original messages. Such methods are more secure and more efficient than typical re-encoding and re-encryption schemes, and are useful in developing such applications as document distribution and long-term file protection.

US Patent:

6885748, Apr 26, 2005

Filed:

Mar 24, 2000

Appl. No.:

09/536089

Inventors:

Xin Wang - Los Angeles CA, US

Assignee:

ContentGuard Holdings, Inc. - Wilmington DE

International Classification:

H04N007/167
H04L009/00

US Classification:

380201, 380212, 713160, 713193, 705 51, 705 57

Abstract:

A method of protecting a digital work uses a format preserving encryption scheme to encrypt the digital work. This enables any native replay application or rendering application to transform an encrypted digital work into encrypted presentation data. The originator's digital content is protected in its original form by not being decrypted. This method enables the rendering or replay application to process the encrypted document into encrypted presentation data without decrypting it first. Encrypted presentation data is then decrypted just before it is displayed to the user. An additive encryption scheme is a particular type of encryption scheme which preserves formatting of a digital work.

US Patent:

6912294, Jun 28, 2005

Filed:

Dec 29, 2000

Appl. No.:

09/749895

Inventors:

Xin Wang - Los Angeles CA, US
Steve Atsushi Okamoto - Torrance CA, US
Russell Robert Lear - Torrance CA, US
Nancy Lynn Ishigo - Torrance CA, US

Assignee:

ContentGuard Holdings, Inc. - Wilmington DE

International Classification:

G06K009/00

US Classification:

382100, 713176

Abstract:

A multi-stage watermarking system and process that creates a watermark specification which describes how to generate a watermark, generates a template specification which describes how to merge the watermark into a target document, generates the watermark based on the watermark specification, and merges the watermark into the target document based on the template specification to provide a watermarked document.

US Patent:

6931545, Aug 16, 2005

Filed:

Aug 28, 2000

Appl. No.:

09/649838

Inventors:

Thanh Ta - Huntington Beach CA, US
Xin Wang - Los Angeles CA, US

Assignee:

ContentGuard Holdings, Inc. - Wilmington DE

International Classification:

G06F011/30
G06F012/14
H04L009/32
H04L009/00

US Classification:

713200, 713156, 713187

Abstract:

A content provider, such as a document publisher or distributor, provides, for example, protected content to a user, for consumption within a trusted user environment. By providing integrity certification and verification services, the authenticity of the content consumption environments can be verified. The content provider forwards to the user a protected version of the digital content which includes, for example, a license agreement and an integrity profile identification. The profile includes, for example, the applications and system components that are allowed to be used in conjunction with the protected content. Additionally, the content provider initiates a request for an integrity profile. This request for the integrity profile is forwarded to an integrity certification and verification device. The integrity certification and verification device can, for example, if an integrity profile does not already exist for the requested applications and/or systems components, query a content consumption system/application provider, who, for example, has supplied the system components to the user.