Repurposing digitally signed information

A method for repurposing a signed electronic document, the electronic document including repurposable information, the method comprising:

• receiving an electronic document including repurposable information, repurposing constraints, and a digital signature, the repurposing constraints defining one or more authorized uses for the repurposable information, the repurposable information being less than all of the information in the electronic document, the digital signature authenticating the repurposable information, the digital signature verifying that the repurposable information and the repurposing constraints have not been altered after being signed with the digital signature, the digital signature being maintained by the authorized destination when the repurposable information is repurposed;
• validating destination information in the repurposing constraints, the destination information identifying an output destination as an authorized destination;
• and
• using the repurposable information as signed information at the output destination.

A method for assigning a signature to an electronic document, the method comprising:

• displaying a representation of information in an electronic document;
• receiving user input designating information in the electronic document for repurposing, the designated information being less than all of the information in the electronic document;
• associating one or more repurposing constraints with the designated information, the repurposing constraints defining one or more authorized destinations for the designated information;
• and
• generating a digital signature for the designated information and the one or more repurposing constraints, the digital signature authenticating the repurposable information and the one or more repurposing constraints, the digital signature verifying that the repurposable information and the one or more repurposing constraints have not been altered after being signed with the digital signature, the digital signature being maintained by the authorized destination when the repurposable information is repurposed.

A data structure associated with an electronic document, the data structure being stored on a computer-readable medium, the data structure comprising:

• a subset of information of the electronic document;
• one or more constraints on repurposing assigned to the subset of information, the constraints defining one or more authorized uses for the subset of information;
• and
• a signature assigned to the subset of information and the one or more constraints, the signature authenticating the subset of information and the one or more constraints, the digital signature verifying that the repurposable information and the one or more repurposing constraints have not been altered after being signed with the digital signature.

A computer program product, tangibly stored on a computer-readable medium, the product comprising instructions operable to cause a computer system to:

• identify repurposable information in an electronic document, the repurposable information being less than all of the content in the electronic document;
• define one or more repurposing constraints for the repurposable information, the repurposing constraints identifying an authorized destination for the repurposable information;
• and
• sign the repurposable information and the one or more repurposing constraints with a digital signature, the digital signature authenticating the repurposable information, the digital signature verifying that the repurposable information has not been altered since it was signed, the digital signature being maintained by the authorized destination when the repurposable information is repurposed.

A computer program product, tangibly stored on a computer-readable medium, for repurposing a signed electronic document, the electronic document including repurposable information, the product comprising instructions operable to cause a computer system to:

• receive an electronic document including repurposable information, repurposing constraints, and a digital signature, the repurposing constraints defining one or more authorized uses for the repurposable information, the repurposable information being less than all of the information in the electronic document, the digital signature authenticating the repurposable information, the digital signature verifying that the repurposable information and the repurposing constraints have not been altered after being signed with the digital signature, the digital signature being maintained by the authorized destination when the repurposable information is repurposed;
• validate destination information in the repurposing constraints, the destination information identifying an output destination as an authorized destination;
• and
• use the repurposable information as signed information at the output destination.

A computer program product, tangibly stored on a computer-readable medium, for assigning a signature to an electronic document, the product comprising instructions operable to cause a computer system to:

• display a representation of information in an electronic document;
• receive user input designating information in the electronic document for repurposing, the designated information being less than all of the information in the electronic document;
• associate one or more repurposing constraints with the designated information, the repurposing constraints defining one or more authorized destinations for the designated information;
• and
• generate a digital signature for the designated information and the one or more repurposing constraints, the digital signature authenticating the repurposable information and the one or more repurposing constraints, the digital signature verifying that the repurposable information and the one or more repurposing constraints have not been altered after being signed with the digital signature, the digital signature being maintained by the authorized destination when the repurposable information is repurposed.

A system comprising:

• means for identifying repurposable information in an electronic document, the repurposable information being less than all of the content in the electronic document;
• means for defining one or more repurposing constraints for the repurposable information, the repurposing constraints identifying an authorized destination for the repurposable information;
• and
• means for signing the repurposable information and the one or more repurposing constraints with a digital signature, the digital signature authenticating the repurposable information, the digital signature verifying that the repurposable information has not been altered since it was signed, the digital signature being maintained by the authorized destination when the repurposable information is repurposed.

A system comprising:

• means for receiving an electronic document including repurposable information, repurposing constraints, and a digital signature, the repurposing constraints defining one or more authorized uses for the repurposable information, the repurposable information being less than all of the information in the electronic document, the digital signature authenticating the repurposable information, the digital signature verifying that the repurposable information and the repurposing constraints have not been altered after being signed with the digital signature, the digital signature being maintained by the authorized destination when the repurposable information is repurposed;
• means for validating destination information in the repurposing constraints, the destination information identifying an output destination as an authorized destination;
• and
• means for using the repurposable information as signed information at the output destination.

A system comprising:

• means for displaying a representation of information in an electronic document;
• means for receiving user input designating information in the electronic document for repurposing, the designated information being less than all of the information in the electronic document;
• means for associating one or more repurposing constraints with the designated information, the repurposing constraints defining one or more authorized destinations for the designated information;
• and
• means for generating a digital signature for the designated information and the one or more repurposing constraints, the digital signature authenticating the repurposable information and the one or more repurposing constraints, the digital signature verifying that the repurposable information and the one or more repurposing constraints have not been altered after being signed with the digital signature, the digital signature being maintained by the authorized destination when the repurposable information is repurposed.