Uniquely linking security elements in identification documents

Abstract

We provide techniques for uniquely linking security elements in identification documents. In one implementation we provide a digital watermark embedded embedded on, and a smartcard chip embedded in, an identification document. The smart card chip includes a hash or a reduced-bit representation of the digital watermark, while the digital watermark includes a hash of information stored on the smartcard chip. In another implementation we cross-correlate encryption keys carried by various machine-readable features on an identification document. In still another implementation, we embed biometric information, which is stored in smartcard electronic circuitry, with a digital watermark. In one case the watermark is reversible, so that it can be removed to yield unmarked biometric information. In another case the watermark is fragile, to reveal whether the biometric information has been subjected to a transformation. In yet another implementation, we provide a jurisdictional indicator on an identification document. The jurisdictional indicator helps in decoding a digital watermark on the identification document.

1 . A method of verifying a document with a smart card chip comprising: 
 computing a hash of a digital watermark to be embedded in the document;    storing the hash in the smart card chip;    computing a hash of data stored in the smart card chip; and    embedding the hash of the data stored in the smart card chip in a digital watermark on the document.    
     
     
         2 . The method of  claim 1  wherein a list of hashes of separate digital watermarks on the document are stored in the smart card chip.  
     
     
         3 . The method of  claim 1  wherein the hash is randomized before being stored in the smart card chip.  
     
     
         4 . A computer readable medium on which is stored instructions for performing the method of  claim 1 .  
     
     
         5 . The method of  claim 1  wherein the digital watermark is embedded in a optically variable device.  
     
     
         6 . The method of  claim 5  wherein the optically variable device comprises a Kinegram®.  
     
     
         7 . A method of verifying integrity of a document comprising: 
 capturing an image scan of the document, including a scan of an optically variable device;    extracting a digital watermark from the image to check the integrity of the optically variable device;    comparing information in the digital watermark with information in another security element captured in the image; and    extracting a printer or issuer identifier from the image to check the source of the document.    
     
     
         8 . The method of  claim 7  wherein the digital watermark is embedded in an image conveyed by the optically variable device.  
     
     
         9 . The method of  claim 7  wherein the digital watermark carries data or attribute information about the optically variable device which is used to verify the integrity of the optically variable device.  
     
     
         10 . A computer readable medium on which is stored instructions for performing the method of  claim 1 .  
     
     
         11 . A method of verifying a document comprising: 
 determining jurisdictional information related to the document, wherein the jurisdictional information is mathematically related to a digital watermark embedded in the document; and    using the jurisdictional information to extract the digital watermark embedded in the document.    
     
     
         12 . A method of verifying a document comprising: 
 extracting a public key from a machine readable feature on the document;    extracting a message payload from another machine readable feature on the document, the message payload being encrypted by a private key that forms part of a public-private key pair with the public key; and    using the public key to de-scramble the message payload.    
     
     
         13 . The method of  claim 12  wherein at least one of the machine readable features is a optically variable device.  
     
     
         14 . The method of  claim 12  wherein at least one of the machine readable features is a digital watermark.  
     
     
         15 . The method of  claim 12  wherein the message payload is a digital watermark message payload, and the public key is stored in a machine readable optically variable device.  
     
     
         16 . A document comprising: 
 a substrate; and    an optically variable device attached to the substrate, the optically variable device having a diffraction pattern that conveys a first image at a first orientation of the document, and a second image at a second orientation of the document, wherein the first and second images form a figure ground reversal enabling visual verification of the document.    
     
     
         17 . The document of  claim 16  wherein at least one of the images carries an embedded digital watermark.  
     
     
         18 . The document of  claim 16  wherein the relationship between the first and second images is used to verify the integrity of the document.  
     
     
         19 . The document of  claim 18  wherein the relationship is automatically compared and verified by machine-reading.  
     
     
         20 . A document having a smart card chip, the smart card chip carrying a digital watermark used to authenticate the data stored on the smart card chip.  
     
     
         21 . The document of  claim 20  wherein the digital watermark is embedded in data stored in the smart card chip.  
     
     
         22 . The document of  claim 21  wherein the data comprises an image.  
     
     
         23 . The document of  claim 21  wherein the data comprises a biometric of the bearer of the document.  
     
     
         24 . The method of  claim 21  wherein the digital watermark is reversible such that it can be substantially removed from the host data in which it is embedded to restore the host data.  
     
     
         25 . The method of  claim 21  wherein the digital watermark is reversible such that it can be perfectly removed from the host data in which it is embedded to restore the host data.  
     
     
         26 . The method of  claim 21  wherein the digital watermark is designed to be lost or degraded when subjected to a transformation.  
     
     
         27 . A method of verifying a document comprising: 
 determining jurisdictional information related to the document, wherein the jurisdictional information is used to obtain a watermark key which is related to a digital watermark embedded in the document; and    using the key to extract the digital watermark embedded in the document.    
     
     
         28 . The method of  claim 27 , wherein the document comprises a machine-readable feature, which carries the jurisdictional information, and wherein said determining step comprises reading the machine-readable feature.  
     
     
         29 . The method of  claim 27 , wherein the jurisdictional information comprises an index, which is used to interrogate a database to obtain the watermarking key.  
     
     
         30 . The method of  claim 27 , wherein the jurisdictional information is combined with predetermined data to form the watermarking key.  
     
     
         31 . The method of  claim 27 , wherein the jurisdictional information comprises the watermarking key.  
     
     
         32 . The method of  claim 28 , wherein the jurisdictional information comprises the watermarking key.  
     
     
         33 . The method of  claim 11 , wherein the jurisdictional information is mathematically related to the digital watermark through a cryptographic relationship.  
     
     
         34 . The method of  claim 11 , wherein the jurisdictional information is mathematically related to the digital watermark through a watermarking key.  
     
     
         35 . A method of verifying a document, the document comprising optical memory having first information stored therein and a digital watermark carrying second information, said method comprising: 
 reading the optical memory to obtain the first information, wherein the first information is related to the digital watermark; and    using at least the first information, extracting the digital watermark embedded in the document to obtain the second information.    
     
     
         36 . The method of  claim 35 , wherein said reading step comprises optically capturing at least a portion of the optical memory and at least a portion of the digital watermark using the same optical sensor.