Watermarking systems and methods

• US 20040250080A1
• Filed: 02/05/2004
• Published: 12/09/2004
• Est. Priority Date: 02/05/2003
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Levy, Kenneth L., Stach, John, Sharma, Ravi K., Shen, Lance Lixin
• Granted Patent: US 7,702,125 B2
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant

Abstract

Various improvements and applications for digital watermarking technology are detailed. One concerns techniques for making watermarks resistant to malicious attacks. Another involves using digital watermarking with ID cards and credentials, such as a watermarked driver'"'"'s license conveying a user'"'"'s cryptographic PKI. Still another uses digital watermarks in connection with automated compliance audits for corporate users of electronic content. A variety of other technologies are also detailed.

Claims

1. In a method that includes encoding one or more content objects with a steganographic digital watermark, the encoding including embedding a collection of features that can be used to facilitate computation of geometrical distortion of the object after encoding, an improvement including step for making the collection of geometrical features resistant to attack.

2. The method of claim 1 wherein said step includes adding said collection of geometrical features in some of said objects, and subtracting said collection of geometrical features from other of said objects.

3. The method of claim 1 wherein said step includes embedding said collection of geometrical features at a first scale in a first object, and embedding said collection of geometrical features at a second, different scale in a second object.

4. The method of claim 1 wherein said step includes embedding said collection of geometrical features at a first orientation in a first object, and embedding said collection of geometrical features at a second, different orientation in a second object.

5. The method of claim 1 wherein said step includes obscuring said collection of geometrical features by designing same to become apparent only in an alternate domain.

6. In a method that includes decoding a steganographic digital watermark from an encoded object, the encoding including a template signal that aids in determining corruption of the object, an improvement comprising step for detecting the template signal without log-polar remapping.

7. An identity card for a person, the card including machine-readable data conveying a public key identifier associated with said person, the public key identifier being useful in cryptographic operations involving said person.