Method and system for mixed symmetric and asymmetric encryption of .ZIP files

• US 8,225,108 B2
• Filed: 09/20/2004
• Issued: 07/17/2012
• Est. Priority Date: 07/16/2003
• Status: Active Grant

• Current Assignee: PKWARE, Inc. (PKW Holdings, Inc.)
• Original Assignee: PKWARE, Inc. (PKW Holdings, Inc.)
• Inventors: Peterson, James C.
• Primary Examiner(s): Dinh, Minh
• Application Number:
  US10/945,292
• Publication Number:
  US 20050091517A1
• Time in Patent Office: 2,857 Days
• Field of Search: None
• US Class Current: 713/193
• CPC Class Codes: G06F 16/1744 using compression, e.g. sparse files
• 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 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 2221/2107 File encryption
• CPC Class Codes: G06F 2221/2153 Using hardware token as a secondary aspect
• CPC Class Codes: H04L 2209/30 Compression, e.g. Merkle-Damgard construction
• CPC Class Codes: H04L 9/0819 Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) network architectures or network communication protocols for key distribution in a packet data network H04L63/062
• CPC Class Codes: H04L 9/088 Usage controlling of secret information, e.g. techniques for restricting cryptographic keys to pre-authorized uses, different access levels, validity of crypto-period, different key- or password length, or different strong and weak cryptographic algorithms network architectures or network communication protocols for using time-dependent keys in a packet data network H04L63/068

Abstract

The present invention provides a method of integrating existing strong encryption methods into the processing of a .ZIP file to provide a highly secure data container which provides flexibility in the use of symmetric and asymmetric encryption technology. The present invention adapts the well established .ZIP file format to support higher levels of security and multiple methods of data encryption and key management, thereby producing a highly secure and flexible digital container for electronically storing and transferring confidential data.

Claims

1. A method of placing data in a .Zip file format data container, said method including:

receiving a data file;

generating a first symmetric key based on a user input;

generating random data;

generating a second symmetric key based at least in part on said random data;

encrypting said data file to form an encrypted data file, wherein said encrypting includes symmetrically encrypting said data file using said second symmetric key;

symmetrically encrypting said random data using said first symmetric key to generate symmetrically encrypted key data;

asymmetrically encrypting said first symmetric key using an asymmetric key to form asymmetrically encrypted key data;

placing first data representing said symmetrically encrypted key data in a data container; and

placing second data representing said asymmetrically encrypted key data in said data container, wherein said second data is distinct from said first data, wherein said data container is constructed in accordance with a .Zip file format,

wherein all of the steps above are performed on a computing device.

2. The method of claim 1 wherein said encrypted data file is also placed in said data container.

3. The method of claim 1 further including:

compressing said data file before symmetrically encrypting said data file.

4. The method of claim 3 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.

5. The method of claim 3 wherein said compressing employs a Deflate-type data compression algorithm.

6. The method of claim 3 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.

7. The method of claim 1 further including:

symmetrically encrypting said data file without compressing said data file.

8. The method of claim 1 wherein said asymmetrically encrypting employs a public key.

9. The method of claim 1 wherein said asymmetrically encrypting employs a X.509 digital certificate.

10. The method of claim 1 wherein said at least part of said first symmetric key is a password.

11. A .Zip file format data container recorded on a non-transitory computer readable medium, said data container including:

an encrypted data file recorded on a computer readable medium;

first data representing symmetrically encrypted key data recorded on said computer readable medium; and

second data representing asymmetrically encrypted key data recorded on said computer readable medium,

wherein said second data is distinct from said first data;

wherein a first symmetric key is based on a user input;

wherein said symmetrically encrypted key data is-generated by symmetrically encrypting said random data using said first symmetric key,

wherein a second symmetric key is generated based at least in part on said random data;

wherein said encrypted data file has been symmetrically encrypted using said second symmetric key,

wherein asymmetrically encrypted key data is generated by asymmetrically encrypting said first symmetric key using an asymmetric key,

wherein said data container is constructed in accordance with a .Zip file format.

12. The .Zip file format data container of claim 11 wherein said encrypted data file is also placed in said data container.

13. The .Zip file format data container of claim 11 wherein said encrypted data file has been compressed before encryption.

14. The .Zip file format data container of claim 13 wherein said encrypted data file has been compressed before encryption using a Lempel-Ziv (LZ)-type data compression algorithm.

15. The .Zip file format data container of claim 13 wherein said encrypted data file has been compressed before encryption using a Deflate-type data compression algorithm.

16. The .Zip file format data container of claim 13 wherein said encrypted data file has been compressed before encryption using a Burrows-Wheeler Transform (BWT)-type data compression algorithm.

17. The .Zip file format data container of claim 11 wherein said asymmetrically encrypting employs a public key.

18. The .Zip file format data container of claim 11 wherein said asymmetrically encrypting employs a X.509 digital certificate.

19. The .Zip file format data container of claim 11 wherein said at least part of said first symmetric key is a password.

20. The .Zip file format data container of claim 11 wherein said encrypted data file has not been compressed before encryption.

21. A method of placing data in a data container, said method including:

receiving a data file;

generating a first symmetric key based on a user input;

generating random data;

generating a second symmetric key based at least in part on said random data;

encrypting said data file to form an encrypted data file, wherein said encrypting includes symmetrically encrypting said data file using said second symmetric key;

symmetrically encrypting said random data using said symmetric key to generate symmetrically encrypted key data;

asymmetrically encrypting said first symmetric key using an asymmetric key to form asymmetrically encrypted key data;

placing first data representing said symmetrically encrypted key data in a data container; and

placing second data representing said asymmetrically encrypted key data in said data container, wherein said second data is distinct from said first data, wherein said data container is designed for containing compressed files,

wherein all of the steps above are performed on a computing device.

22. The method of claim 21 wherein said encrypted data file is also placed in said data container.

23. The method of claim 21 further including:

compressing said data file before symmetrically encrypting said data file.

24. The method of claim 23 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.

25. The method of claim 23 wherein said compressing employs a Deflate-type data compression algorithm.

26. The method of claim 23 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.

27. The method of claim 21 further including:

symmetrically encrypting said data file without compressing said data file.

28. The method of claim 21 wherein said asymmetrically encrypting employs a public key.

29. The method of claim 21 wherein said asymmetrically encrypting employs a X.509 digital certificate.

30. The method of claim 21 wherein said at least part of said first symmetric key is a password.

31. A data container recorded on a non-transitory computer readable medium, said data container including:

an encrypted data file recorded on a computer readable medium;

first data representing symmetrically encrypted key data recorded on said computer readable medium; and

second data representing asymmetrically encrypted key data recorded on said computer readable medium,

wherein said second data is distinct from said first data;

wherein a first symmetric key is based on a user input;

wherein said symmetrically encrypted key data is generated by symmetrically encrypting said random data using said first symmetric key,

wherein a second symmetric key is generated based at least in part on said random data;

wherein said encrypted data file has been symmetrically encrypted using said second symmetric key,

wherein said asymmetrically encrypted key data is generated by asymmetrically encrypting said first symmetric key using an asymmetric key,

wherein said data container is designed for containing compressed files.

32. The data container of claim 31 wherein said encrypted data file is also placed in said data container.

33. The data container of claim 31 wherein said encrypted data file has been compressed before encryption.

34. The data container of claim 33 wherein said encrypted data file has been compressed before encryption using a Lempel-Ziv (LZ)-type data compression algorithm.

35. The data container of claim 33 wherein said encrypted data file has been compressed before encryption using a Deflate-type data compression algorithm.

36. The data container of claim 33 wherein said encrypted data file has been compressed before encryption using a Burrows-Wheeler Transform (BWT)-type data compression algorithm.

37. The data container of claim 31 wherein said asymmetrically encrypting employs a public key.

38. The data container of claim 31 wherein said asymmetrically encrypting employs a X.509 digital certificate.

39. The data container of claim 31 wherein said at least part of said first symmetric key is a password.

40. The data container of claim 31 wherein said encrypted data file has not been compressed before encryption.