Method and apparatus for binding electronic impressions made by digital identities to documents

• US 6,401,206 B1
• Filed: 03/05/1998
• Issued: 06/04/2002
• Est. Priority Date: 03/06/1997
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Skylight Software Incorporated
• Inventors: Khan, Shabbir A., Rajput, Saeed A., Hussain, Basit
• Primary Examiner(s): Barron, Jr., Gilberto
• Assistant Examiner(s): MEISLAHN, DOUGLAS J
• Application Number:
  US09/035,670
• Time in Patent Office: 1,552 Days
• Field of Search: 713/176, 713/183
• US Class Current: 713/176
• CPC Class Codes: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 9/3231 Biological data, e.g. fingerprint, voice or retina network architectures or network communication protocols for supporting authentication of entities using biometrical features in a packet data network H04L63/0861
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

This invention creates a portable digital identity of the individual that includes personal information, and may also include data representing the person'"'"'s handwritten signature and one or more passwords. The digital identity optionally includes data representing seals, fingerprints and biometric information. The digital identity can be used to bind a verifiable electronic impression with an electronic document using electronic watermarks so that any modification in the document or the electronic impression bound to the document can be detected. The personal information included in the digital identifiers can include, in addition to a password, answers to questions that are composed by the user. The digital identity of a user can be created once and stored after encryption for protection. This digital identity can then be used by the signer to bind a unique instance of an impression of the digital identity to any document. Document and digital identity verification including verifying a cryptographic digital signature that establishes the integrity of the document, and ensures non-repudiation of origin to the extent that it was signed by the user'"'"'s private key.

Claims

1. A method of creating a digital identity for a person suitable for use when digitally signing documents, the method comprising the steps of:

generating a private digital representation of private information known only to the person, the private information including individual-specific questions and individual-specific answers provided by the person;

generating a public digital representation of public information about the person;

generating at least one public/private key pair for the person, and associating the private key with the person;

generating at least one symmetric key, suitable for symmetric encryption/decryption, deduced from information including personal information;

generating one or more sets of recoverable and non-recoverable personal identifiers based on public and private information including the individual-specific questions and individual-specific answers;

encrypting the public and private digital representations, the private key of the public/private key pair and the personal identifiers using the symmetric key to generate the digital identity; and

computation of multiple identity marks that are based upon data that is contained in and/or is derived from the digital identity, in particular the personal identifiers, as well as other information including a document and data that is unique to each instance of a signature on a digital document, wherein each instance of the signature is unique and verifiable by the owner of the digital identity, recipient(s) of the document and/or third parties verifying the signature and/or the digital document.

2. The method of claim 1, wherein the symmetric key is generated from a subset of information including user'"'"'s name and static private information.

3. The method of claim 1, wherein additional information includes data selected from the set consisting of a person'"'"'s picture, handwritten signatures, stamp and seal, and the person'"'"'s biometric data including fingerprints, speech, and retina scans.

4. The method of claim 1, including the steps of:

computing recoverable personal identifier 1 by applying a hash function to the result of a concatenation operation performed on data including the person'"'"'s public name and static private information;

computing recoverable personal identifier 2 by applying a hash function to the result of a concatenation operation performed on data including personal identifier 1, individual-specific public questions and individual-specific private answers;

computing unrecoverable personal identifier 3 by applying the hash function to the result of a concatenation operation performed on data including personal identifier 2, handwritten signature and/or images and other biometric information;

wherein at least one recoverable personal identifier, personal identifier 1, can be regenerated by the person signing the document and/or by any authority which has access to the static private information of the user by reapplying the hash function to the static information including the static private information;

wherein at least one recoverable personal identifier, personal identifier 2, can be regenerated by reapplying the hash function to exactly the same public and private information while recovering the digital identity;

wherein at least one unrecoverable personal identifier, personal identifier 3, is generated using techniques that do not reliably produce exactly identical results with each repetition.

5. The method of claim 1, including storing the digital identity on a portable storage device readable by a computer.

6. The method of claim 5, including affixing a photograph of the owner of the digital identity on an exterior surface of the storage device to serve as a Picture ID.

7. The method of claim 5, wherein owner associated identification information is stored in a magnetic strip affixed to the portable storage device.

8. The method of claim 5, further comprising the steps of:

storing with the digital identity an indication of a desired level of security; and

applying the indicated level of security, when using the digital identity to digitally sign a document, including the steps of;

authenticating a user'"'"'s ownership of the digital identity by accepting data including user name, pin number and password for regenerating the key suitable for symmetric encryption/decryption;

rejecting the user when user'"'"'s ownership is not authenticated as the regenerated symmetric key fails to decrypt the digital identity;

further authenticating a user'"'"'s ownership of the digital identity by requesting additional information including individual-specific private answers to individual-specific public questions, wherein the type of information being requested is randomly selected from a set of data contained in the digital identity, with members of the data set being chosen based upon the desired level of security stored as part of the digital identity; and

rejecting the user when user'"'"'s ownership is not authenticated.

9. The method of claim 5, including having a trusted third party certify public information components of the digital identity and durably storing a record of the certification.

10. The method of claim 9, wherein the public information components of the digital identity are stored in a repository for reconstruction and recovery.

11. The method of claim 9, wherein the public information components of the digital identity are kept in escrow with one or more trusted third parties.

12. The method of claim 5, further comprising the steps of:

editing the digital identity, and storing with the digital identity history data representing changes made to the digital identity.

13. The method of claim 4, wherein copies of at least two different ones of the personal identifiers are kept in escrow with at least two respective trusted third parties.

14. The method of claim 8, for binding an electronic impression of the digital identity to a digital document, by:

authenticating a user'"'"'s ownership of the digital identity;

rejecting the user when user'"'"'s ownership is not authenticated;

creating identity marks corresponding to the personal identifiers, each identity mark being created by performing a hash function on a combination of information including one of the personal identifiers, information uniquely associated with the document and its contents; and

applying a cryptographic function to at least one set of information to create a digital signature, wherein the instructions for assembling each set of information further comprises instructions for;

selecting information related to one of the identity marks;

selecting information uniquely associated with the document including its contents;

selecting information uniquely associated with the electronic impression being made by the digital identity; and

binding at least one of the digital signatures, corresponding to one of the identity marks, to a representation of the document.

15. The method of claim 14, wherein the information to which the cryptographic function is applied includes positional information providing a basis for detecting:

use of the digital signature at a position different from the original position within the document; and

/or use of the digital signature on a document that is different than or modified from the document to which the digital signature was bound;

wherein the step of computing positional information further comprises the steps of;

computing positional information in a coordinate system relative to the document; and

/or

computing positional information as a relative address within the document; and

/or

computing positional information as an index to a node if the document is being represented by a tree consisting of one or more nodes.

16. The method of claim 14, wherein the information to which the cryptographic function is applied includes a serial number, the serial number providing a basis for detecting duplicate usage of the digital signature.

17. The method of claim 14, wherein the information to which the cryptographic function is applied includes a timestamp and/or a random number, the timestamp and/or a random number providing a basis for detecting duplicate usage of the digital signature.

18. The method of claim 14, including the steps of:

verifying the digital impression of the digital identity on the document by separating the document from at least one of the digital signatures and corresponding information including the positional information, serial number, random number and/or timestamp and public components of the digital identity that are bound with the document as part of the digital impression;

decrypting the digital signature; and

verifying the digital signature.

19. The method of claim 18, wherein the step of verifying the digital signature includes obtaining one or more personal identifiers associated with the person alleged to have digitally signed the document directly from the digital identity of the alleged signer or from one or more trusted third parties with whom the personal identifiers have been stored.

20. The method of claim 18, wherein the step of verifying the digital signature includes recomputing a set of identity marks and comparing the recomputed identity marks with the identity mark obtained from the digital signature that is part of the electronic impression bound to the document.

21. The method of claim 18, wherein the step of verifying the digital signature includes a step selected from the set consisting of:

comparing the digital signature with another digital signature by the same alleged signer;

comparing current biometric data associated with the alleged signer with biometric data included in the digital impression bound to the document; and

requiring the alleged signer to provide at least some of the answers to the questions included in the personal information that is included in the digital identity that was used to sign the document.

22. The method of claim 8, wherein the step of applying the indicated level of security further comprises the steps of:

authenticating a user'"'"'s ownership of the digital identity by accepting a subset of data including user'"'"'s name and static private information for computing a key suitable for symmetric encryption/decryption; and

rejecting the user when user'"'"'s ownership is not authenticated and the symmetric key fails to decrypt the digital identity.

23. The method of claim 8, wherein the desired level of security is changed by the owner of the digital identity.

24. The method of claim 8, wherein the digital identity is stored on a storage media attached to a computer system, accessible to the owner of the identity, and the digital identity is used for authentication including logging on to computers.

25. The method of claim 24, wherein the digital identity is used for signing digital documents.

26. The method of claim 24, wherein the step of authentication further comprises the steps of creating and using a password from the personal information including the personal identifiers of the person seeking authentication.

27. The method of claim 24, wherein the desired level of security is changed by the owner of the digital identity.

28. The method of claim 8, wherein the step of applying desired level of security further comprises the steps of:

detecting that a user is unable to prove, through finite number of trials, ownership of the digital identity;

locking the system for a deterministic wait period; and

erasing the digital identity information from the volatile memory.

29. The method of claim 24, wherein the step of authentication further comprises the steps of:

detecting that a user is unable to prove, through finite number of trials, ownership of the digital identity;

locking the system for a deterministic wait period; and

erasing the digital identity information from the volatile memory.

30. The method of claim 25, wherein the step of signing further comprises the steps of:

detecting that a user is unable to prove, through finite number of trials, ownership of the digital identity;

locking the system for a deterministic wait period; and

erasing the digital identity information from the volatile memory.

31. The method of claim 28, wherein the step of locking the system further comprises the step of changing the level of security to a higher level to make the digital identity more securer against potential attacks.

32. The method of claim 29, wherein the step of locking the system further comprises the step of changing the level of security to a higher level to make the digital identity more securer against potential attacks.

33. The method of claim 30, wherein the step of locking the system further comprises the step of changing the level of security to a higher level to make the digital identity more secure against potential attacks.

34. The method of claim 12, wherein at least one of the personal identifiers is stored with a third party for notarization and durably storing a record of the notarization.

35. The method of claim 34, wherein the step of storing at least one of the personal identifiers with a third party, further comprises the steps of:

owner of the digital identity creating at least one additional public/private key pair;

encrypting the personal identifiers using the public key of a public/private key pair; and

storing the encrypted version of one of the personal identifiers with the third party.

36. The method of claim 14, wherein at least one of the identity marks is stored with a third party for notarization and durably storing a record of the notarization.

37. The method of claim 36, wherein the step of storing at least one of the identity marks with a third party, further comprises the steps of:

owner of the digital identity creating at least one additional public/private key pair;

encrypting the identity mark using the public key of a public/private key pair; and

storing the encrypted version of one of the identity marks with the third party.

38. The method of claim 12, further comprising the steps of:

editing the digital identity, and storing with the digital identity additional data including owner profile information for use with electronic systems over the Internet.

39. The method of claim 35, wherein copies of at least two different ones of the encrypted personal identifiers are kept in escrow with at least two respective trusted third parties.

40. The method of claim 37, wherein copies of at least two different ones of the encrypted identity marks are kept in escrow with at least two respective trusted third parties.

41. The method of claim 14, wherein at least one of the identity marks is created by performing a hash function to the concatenation of at least one of the personal identifiers with the information uniquely associated with the document including its contents.

42. The method of claim 14, wherein at least one set of information, used for computing one of the digital signatures, includes a hash of the document instead of the document.

43. The method of claim 14, wherein the information to which the cryptographic function is applied includes a random number, the random number providing a basis for detecting duplicate usage of the digital signature.

44. The method of claim 14, wherein one or more signers with each signer, using a digital identity owned by each signer, making one or more electronic impressions to the same document at different positions in the document.

45. The method of claim 44, wherein one or more electronic impressions at multiple locations in the document, made by the same signer or multiple signers, are assembled and bound to the same document comprising the steps of:

assembling and binding one or more electronic impressions in a sequential order; and

/or

assembling and binding one or more electronic impressions in a hierarchical order; and

/or

assembling and binding one or more electronic impressions using a combinations of sequential and hierarchical order.

46. The method of claim 14, further comprising the step of displaying the document and at least a subset of the information associated with the digital impression including biometric data on signer'"'"'s terminal.

47. The method of claim 18, further comprising the step of displaying the document and at least a subset of the information associated with the digital impression including biometric data on the terminal of a recipient and/or a verifier with access to signer'"'"'s public keys.

48. The method of claim 14, wherein the step of binding an electronic impression of the digital identity by a signer further comprising the steps of:

inserting at least one more electronic impressions, in the same document, by the signer after reauthenticating himself with the digital identity; and

/or

deleting at least one or more electronic impressions belonging to the signer, from the same document, by the signer after reauthenticating himself with the digital identity.

49. The method of claim 48, wherein the step of inserting an electronic impression by a signer after the signer has reauthenticated himself, further comprising instructions for:

checking that the signer is inserting the new impression in the document while maintaining a valid sequence or a valid hierarchy or a combination thereof.

50. The method of claim 48, wherein the step of deleting an existing electronic impression made by a signer, belonging to the signer, after the signer has reauthenticated himself, further comprising instructions for:

checking that the signer is deleting the existing impression from the document while maintaining a valid sequence or a valid hierarchy or a combination thereof.

51. The method of claim 50, wherein the step of deleting an existing impression, further comprises a step of:

nullifying and/or invalidating and/or deleting impressions that were made later than the impression being deleted in case of a sequential signature protocol;

nullifying and/or invalidating and/or deleting impressions that are subordinate to the impression being deleted in case of a hierarchical signature protocol;

nullifying and/or invalidating and/or deleting impressions that are subordinate to the impression being deleted along with the impressions that were made later than the impression being deleted or are subordinate to a later impression in case a signature protocol includes both sequential and hierarchical features;

nullifying and/or invalidating and/or deleting the impression in case the signature protocol allows it.

52. A computer program product for use in conjunction with a processor, the computer program product comprising a first computer readable storage medium and a computer program mechanism embedded therein, the computer program mechanism comprising a controller configuration system procedure for creating a digital identity for a person suitable for use when digitally signing documents, the controller configuration system procedure including instructions for:

generating a private digital representation of private information known only to the person, the private information including individual-specific questions and individual-specific answers provided by the person;

generating a public digital representation of public information about the person;

generating at least one public/private key pair for the person, and associating the private key with the person;

generating at least one symmetric key, suitable for symmetric encryption/decryption, deduced from information including personal information;

generating one or more sets of recoverable and non-recoverable personal identifiers based on public and private information including the individual-specific questions and individual-specific answers;

encrypting the public and private digital representations, the private key of the public/private key pair and the personal identifiers using the symmetric key to generate the digital identity; and

computation of multiple identity marks that are based upon data that is contained in and/or is derived from the digital identity, in particular the personal identifiers, as well as other information including a document and data that is unique to each instance of a signature on a digital document, wherein each instance of the signature is unique and verifiable by the owner of the digital identity, recipient(s) of the document and/or third parties verifying the signature and/or the digital document.

53. The computer program product of claim 52, further comprising instructions for:

storing with the digital identity an indication of a desired level of security; and

applying the indicated level of security, when using the digital identity to digitally sign a document, including the steps of;

i. authenticating a user'"'"'s ownership of the digital identity by accepting data including user name, pin number and password for regenerating the key suitable for symmetric encryption/decryption;

ii. rejecting the user when user'"'"'s ownership is not authenticated as the regenerated symmetric key fails to decrypt the digital identity;

iii. further authenticating a user'"'"'s ownership of the digital identity by requesting additional information including individual-specific private answers to individual-specific public questions, wherein the type of information being requested is randomly selected from a set of data contained in the digital identity, with members of the data set being chosen based upon the desired level of security stored as part of the digital identity;

rejecting the user when user'"'"'s ownership is not authenticated.

54. The computer program product of claim 53, including instructions for:

binding an electronic impression of the digital identity to a digital document, by;

authenticating a user'"'"'s ownership of the digital identity;

rejecting the user when user'"'"'s ownership is not authenticated;

creating identity marks corresponding to the personal identifiers, each identity mark being created by performing a hash function on a combination of information including one of the personal identifiers, information uniquely associated with the document and its contents; and

applying a cryptographic function to at least one set of information to create a digital signature, wherein the instructions for assembling each set of information further comprises instructions for;

selecting information related to one of the identity marks;

selecting information uniquely associated with the document including its contents;

selecting information uniquely associated with the electronic impression being made by the digital identity; and

binding at least one of the digital signatures, corresponding to one of the identity marks, to a representation of the document.

55. The computer program product of claim 54, including instructions for:

verifying the digital impression of the digital identity on the document by separating the document from at least one of the digital signatures and corresponding information including the positional information, serial number, random number and/or timestamp and public components of the digital identity that are bound with the document as part of the digital impression;

decrypting the digital signature; and

verifying the digital signature.

56. The computer program product of claim 52, wherein the symmetric key is generated from a subset of information including user'"'"'s name and static private information.

57. The computer program product of claim 54, wherein the digital identity is stored on a storage media attached to a computer system, accessible to the owner of the identity, and the digital identity is used for authentication including logging on to computers.

58. The computer program product of claim 52, wherein at least one of the personal identifiers is stored with a third party for notarization and durably storing a record of the notarization.

59. The computer program product of claim 52, further comprising instructions for editing the digital identity, and storing with the digital identity additional data including owner profile information for use with electronic systems over the Internet.

60. The computer program product of claim 54, wherein one or more signers with each signer, using a digital identity owned by each signer, making one or more electronic impressions to the same document at different positions in the document.

61. The computer program product of claim 60, wherein one or more electronic impressions at multiple locations in the document, made by the same signer or multiple signers, are assembled and bound to the same document comprising instructions for:

assembling and binding one or more electronic impressions in a sequential order; and

/or

assembling and binding one or more electronic impressions in a hierarchical order; and

/or

assembling and binding one or more electronic impressions using a combinations of sequential and hierarchical order.

62. The computer program product of claim 54, further comprising instructions for displaying the document and at least a subset of the information associated with the digital impression including biometric data on signer'"'"'s terminal.

63. The computer program product of claim 55, further comprising instructions for displaying the document and at least a subset of the information associated with the digital impression including biometric data on the terminal of a recipient and/or a verifier with access to signer'"'"'s public keys.

64. The computer program product of claim 54, wherein the step of binding an electronic impression of the digital identity by a signer further comprising instructions for:

inserting at least one more electronic impressions, in the same document, by the signer after reauthenticating himself with the digital identity; and

/or

deleting at least one or more electronic impressions belonging to the signer, from the same document, by the signer after reauthenticating himself with the digital identity.

65. The computer program product of claim 64, wherein the step of inserting an electronic impression by a signer after the signer has reauthenticated himself, further comprising instructions for:

checking that the signer is inserting the new impression in the document while maintaining a valid sequence or a valid hierarchy or a combination thereof.

66. The computer program product of claim 64, wherein the step of deleting an existing electronic impression made by a signer, belonging to the signer, after the signer has reauthenticated himself, further comprising instructions for:

checking that the signer is deleting the existing impression from the document while maintaining a valid sequence or a valid hierarchy or a combination thereof.

67. The computer program product of claim 57, wherein the digital identity is used for signing digital documents.