Digital Certificate

• US 6,189,097 B1
• Filed: 03/24/1997
• Issued: 02/13/2001
• Est. Priority Date: 03/24/1997
• Status: Expired due to Term

• Current Assignee: SafeNet Data Security (Israel) Ltd.
• Original Assignee: Preview Systems, Inc.
• Inventors: Jennings, Charles W., Tycksen, Frank A. Jr.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/822,661
• Time in Patent Office: 1,422 Days
• Field of Search: 380/25, 380/30, 713/156, 713/160
• US Class Current: 713/156
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3263 involving certificates, e.g. public key certificate [PKC] or attribute certificate [AC]; Public key infrastructure [PKI] arrangements network architectures or network communication protocols for supporting authentication of entities using certificates in a packet data network H04L63/0823

Abstract

A digital certificate includes framing characters defining a protected area. The protected area contains a selected set of components, including text-based components and binary-based components, and the certificate serves as a transport container for such components. A message digest or hashing algorithm applied to the protected area provides consistent results despite modifications to the certificate outside the protected area. A digital signature provides authentication of source and content integrity. Digital certificates under the present invention may be applied to a variety of purposes including but not limited to proof of ownership, gift certificates, upgrade purchases, and other applications where verification of source and content integrity are desirable.

Claims

1. A method of creating a digitally stored digital certificate, the method comprising the steps:

selecting a given character set;

designating from said given character set a protected area border character;

providing said certificate as a sequence of members of said given character set;

defining in said certificate a protected area as members of said given character set located between one and a next occurrence of said protected area border character;

storing at least one digital component in said protected area;

calculating a digital value as a function of digital content stored in said protected area; and

storing a digital signature in said certificate but outside said protected area, said digital signature being encrypted and a function of said value.

2. A method according to claim 1 wherein said protected area is further defined by storage of said border characters wherein said one and said next occurrence of said border character are distinguished from a content occurrence of said border character forming a portion of said digital content.

3. A method according to claim 2 wherein said certificate includes line elements, and at least one of said line elements begins with one of said border characters and ends with one of said border characters.

4. A method according to claim 1 wherein said at least one component comprises a tag field and at least one of a length field and a data field.

5. A method according to claim 4 wherein said data field includes only characters from a restricted character set.

6. A method according to claim 5 wherein said restricted character set corresponds to a subset of an ASCII code character set.

7. A method according to claim 4 wherein said data field is a binary-based data converted from a binary data set to a restricted character set.

8. A method according to claim 7 wherein said restricted character set is a subset of an ASCII code character set.

9. A method according to claim 7 wherein said converted binary-based data is converted to said restricted character set by encoding according to base-64 encoding.

10. A method according to claim 1 wherein said value is a message digest value.

11. A method according to claim 1 wherein said value is calculated by application of a hashing algorithm to characters only in said protected area.

12. A method according to claim 1 wherein said digital signature is converted from a binary data set to a restricted character set.

13. A method according to claim 12 wherein said restricted character set is a subset of an ASCII code set.

14. A method according to claim 12 wherein said converted digital signature is converted to said restricted character set by encoding according to base-64 encoding.

15. A digitally stored digital certificate comprising:

a digital storage medium;

a digital certificate data structure stored upon said storage medium, said data structure defining a protected area as including a sequence of characters occurring between one and a next occurrence of a designated protected area border character;

at least one digital component stored in said protected area; and

a digital signature stored in said certificate data structure but outside said protected area, said digital signature being encrypted and a function of said at least one digital component stored in said protected area.

16. A digital certificate according to claim 15 wherein said protected area is established by storing protected area border characters in a sequence of characters comprising said digital certificate data structure.

17. A digital certificate according to claim 16 wherein said certificate data structure includes line elements, and at least one of said line elements begins with one of said border characters and ends with one of said border characters.

18. A digital certificate according to claim 15 wherein said at least one component comprises a tag field and at least one of a length field and a data field.

19. A digital certificate according to claim 18 wherein said data field includes only characters taken from a restricted character set.

20. A digital certificate according to claim 19 wherein said restricted character set corresponds to a subset of an ASCII code character set.

24. A digital certificate according to claim 15 wherein said value is a message digest value.

25. A digital certificate according to claim 15 wherein said value is calculated by application of a hashing algorithm to characters only in said protected area.

26. A digital certificate according to claim 15 wherein said digital signature is converted from a binary data set to a restricted character set.

27. A digital certificate according to claim 26 wherein said restricted character set is a subset of an ASCII code set.

28. A digital certificate according to claim 26 wherein said converted digital signature is converted to said restricted character set by encoding according to base-64 encoding.

21. A digital certificate according to claim 21 wherein said data field is a binary-based data converted from a binary data set to a restricted character set.

22. A digital certificate according to claim 21 wherein said restricted character set is a subset of an ASCII code character set.

23. A digital certificate according to claim 21 wherein said converted binary-based data is converted to said restricted character set by encoding according to base-64 encoding.

29. A digitally stored digital certificate of product ownership of a given product by a given product owner, said certificate comprising:

a digital storage medium;

a digital certificate data structure stored upon said storage medium, said data structure defining a protected area as including a sequence of characters occurring between one and a next accurrence of a designated protected area border character,;

a first digital component stored in said protected area and identifying said given product;

a second digital component stored in said protected area and identifying said given product owner; and

a digital signature in said certificate data structure but outside said protected area, said digital signature being encrypted and a function of at least said first and second components stored in said protected area.

30. A digital certificate according to claim 29 wherein said protected area is established by storing framing characters in said digital certificate data structure.

31. A digital certificate according to claim 30 wherein said certificate data structure includes line elements, and at least one of said line elements begins with one of said framing characters and ends with one of said framing characters.

32. A digital certificate according to claim 29 wherein said value is a message digest value.

33. A digital certificate according to claim 29 wherein said value is calculated by application of a hashing algorithm to content of said protected area.

34. A digital certificate according to claim 29 wherein said digital signature is converted from a binary data set to a restricted character set.

35. A digital certificate according to claim 34 wherein said restricted character set is a subset of an ASCII code set.

36. A digital certificate according to claim 34 wherein said converted digital signature is converted to said restricted character set by encoding according to base-64 encoding.