Self-protecting documents

• US 6,519,700 B1
• Filed: 10/23/1998
• Issued: 02/11/2003
• Est. Priority Date: 10/23/1998
• Status: Expired due to Term

• Current Assignee: ContentGuard Holdings, Inc. (Pendrell Corporation)
• Original Assignee: ContentGuard Holdings, Inc. (Pendrell Corporation)
• Inventors: Wang, Xin, Ta, Thanh T., Ram, Prasad
• Primary Examiner(s): Barron, Gilberto
• Assistant Examiner(s): Darrow, Justin T.
• Application Number:
  US09/178,529
• Time in Patent Office: 1,572 Days
• Field of Search: 713/193, 713/160, 380/28, 380/42, 380/44, 380/45, 380/47, 380/201, 705/51, 705/56, 705/57
• US Class Current: 713/193
• CPC Class Codes: G06F 21/1063 Personalisation
• CPC Class Codes: G06F 21/107 License processing; Key processing
• CPC Class Codes: G06F 21/16 Program or content traceability, e.g. by watermarking
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 2221/2141 Access rights, e.g. capability lists, access control lists, access tables, access matrices
• CPC Class Codes: G06F 2221/2151 Time stamp

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.

Claims

1. A self-protecting document embodied as data stored on a tangible medium, the self-protecting document comprising:

an encrypted content segment containing data representative of document contents;

a permissions segment; and

a code segment containing executable code for enabling use of the self protecting document,

wherein said code segment comprises a rights enforcement subsection, a rendering subsection, and a polarization subsection.

2. The self-protecting document of claim 1, wherein the polarization subsection comprises a polarization engine and a depolarization engine.

3. The self-protecting document of claim 1, wherein the polarization subsection contains executable computer code adapted to modify the encrypted content segment.

4. The self-protecting document of claim 1, wherein the polarization subsection contains executable computer code adapted to modify the encrypted content segment into a polarized content segment.

5. A method for creating a self-protecting document, comprising the steps of:

receiving an unencrypted document to produce an original content segment;

creating a rights specification;

creating a code segment containing a polarization subsection and executable code for enabling use of the self-protecting document; and

combining the original content segment, the rights specification, and the code segment to produce a generic self-protecting document.

6. The method of claim 5, wherein the modifying step comprises the step of encrypting the unencrypted document.

7. The method of claim 5, wherein the modifying step further comprises the step of pre-processing the unencrypted document.

8. The method of claim 5, further comprising the step of customizing the generic self-protecting document.

9. The method of claim 8, wherein the customizing step comprises the substeps of:

receiving a user'"'"'s document request;

receiving the user'"'"'s public key;

creating a rights and permissions segment consistent with the user'"'"'s document request and the rights specification;

encrypting the original content segment to produce an encrypted content segment; and

combining the code segment, the rights and permissions segment, and the encrypted content segment to produce a customized self-protecting document.

10. A method for using a self-protecting document having an encrypted content segment on a user'"'"'s system, comprising the steps of:

obtaining a polarization key;

modifying the encrypted content segment with the polarization key to produce polarized content;

rendering the polarized content to produce rendered polarized content for output on an output device;

depolarizing the rendered polarized content with the polarization key to produce rendered clear content; and

sending the rendered clear content to the output device.

11. The method of claim 10, wherein the step of modifying the encrypted content segment comprises a substep of transforming the encrypted content segment via an encryption algorithm employing the polarization key.

12. The method of claim 11, wherein the substep of transforming the encrypted content segment comprises the substeps of:

identifying data information and format information within the encrypted content segment;

separating the data information and the formal information from the encrypted content segment;

encrypting the data information with the polarization key; and

combing the encrypted data information with the format information to produce the polarized content.

13. The method of claim 10, wherein the polarization key comprises a combination of state information derived from the user'"'"'s system.

14. A self-protecting document embodied as data stored on a tangible storage medium, the self-protecting document comprising:

an encrypted content segment containing data representative of document contents;

a permissions segment; and

a code segment comprising a polarization subsection.

15. The self-protecting document of claim 14, wherein the polarization subsection comprises a polarization engine and a depolarization engine.

16. The self-protecting document of claim 14, wherein the polarization subsection contains executable computer code adapted to modify the encrypted content segment.

17. The self-protecting of claim 14, wherein the polarization subsection contains executable compute code adapted to modify the encrypted content segment into a polarized content segment.