Method and system for decryption of file characteristics of .ZIP files

• US 20090240952A9
• Filed: 09/20/2004
• Published: 09/24/2009
• Est. Priority Date: 03/09/2001
• Status: Abandoned Application

• Current Assignee: PKWARE, Inc. (PKW Holdings, Inc.)
• Original Assignee: PKWARE, Inc. (PKW Holdings, Inc.)
• Inventors: Peterson, James
• Application Number:
  US10/946,127
• Publication Number:
  US 20050097344A1
• Time in Patent Office: Days
• 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 providing access to a file characteristic of a data file in a .Zip file format data container, said method including:

receiving a data container constructed in accordance with a .Zip file format, said data container including;

a data file; and

an encrypted file characteristic of said data file;

decrypting said encrypted file characteristic to form a decrypted file characteristic; and

providing access to said data file and said decrypted file characteristic.

2. The method of claim 1 wherein said encrypted file characteristic is symmetrically decrypted using a symmetric key.

3. The method of claim 2 wherein at least part of said symmetric key is composed of random data.

4. The method of claim 2 wherein at least part of said symmetric key is input by a user

5. The method of claim 4 wherein said at least part of said symmetric key is a password.

6. The method of claim 2 wherein said symmetric key has a key length of at least 128 bits.

7. The method of claim 2 wherein said symmetric key has a key length of at least 192 bits.

8. The method of claim 2 wherein said symmetric key has a key length of at least 256 bits.

9. The method of claim 2 wherein said at least one file characteristic is symmetrically decrypted using an AES decryption decoding.

10. The method of claim 2 wherein said at least one file characteristic is symmetrically decrypted using a 3DES decryption decoding.

11. The method of claim 1 wherein said at least one file characteristic is asymmetrically decrypted.

14. The method of claim 1 including a plurality of file characteristics.

15. The method of claim 14 wherein not all of said plurality of file characteristics are decrypted.

16. The method of claim 14 wherein at least one of said plurality of file characteristics is decrypted using a first type of decryption and at least one of said plurality of file characteristics is decrypted using a second type of decryption.

17. The method of claim 16 wherein a first of said plurality of file characteristics is decrypted using a first symmetric decryption and a second of said plurality of file characteristics is decrypted using a second symmetric decryption different from said first symmetric decryption.

18. The method of claim 17 wherein said first symmetric decryption employs a key having a first key length and said second symmetric decryption employs a key having a second key length different from said first key length.

19. The method of claim 16 wherein a first of said plurality of file characteristics is decrypted using a first asymmetric decryption and a second of said plurality of file characteristics is decrypted using a second asymmetric decryption different from said first asymmetric encryption.

20. The method of claim 1 wherein said at least one file characteristic includes the name of said data file.

21. The method of claim 1 wherein said at least one file characteristic includes the size of said data file.

22. The method of claim 1 wherein said at least one file characteristic includes the creation date of said data file

23. The method of claim 1 wherein said at least one file characteristic includes the creation time of said data file.

24. The method of claim 1 further including decrypting said data file.

25. The method of claim 24 wherein said data file is decrypted using symmetric decryption.

26. The method of claim 24 wherein said data file is decrypted using asymmetric decryption.

27. The method of claim 24 further including decompressing said file characteristic after decrypting said file characteristic.

28. The method of claim 27 wherein said data file is decompressed using a Lempel-Ziv (LZ)-type data decompression algorithm.

29. The method of claim 27 wherein said data file is decompressed using a Deflate-type data decompression algorithm.

30. The method of claim 27 wherein said data file is decompressed using a Burrows-Wheeler Transform (BWT)-type data decompression algorithm.

31. The method of claim 24 wherein said data file is not decompressed.

32. The method of claim 1 further including decompressing said file characteristic.

12. The method of claim 12 wherein said asymmetric decryption employs a private key.

13. The method of claim 12 wherein said asymmetric decryption employs a X.509 digital certificate.

33. A method of providing access to a file characteristic of a data file in a data container, said method including:

receiving a data container designed for containing compressed file, said data container including;

a data file; and

an encrypted file characteristic of said data file;

decrypting said encrypted file characteristic to form a decrypted file characteristic; and

providing access to said data file and said decrypted file characteristic.

34. The method of claim 33 wherein said encrypted file characteristic is symmetrically decrypted using a symmetric key.

35. The method of claim 34 wherein at least part of said symmetric key is composed of random data.

36. The method of claim 34 wherein at least part of said symmetric key is input by a user

37. The method of claim 36 wherein said at least part of said symmetric key is a password.

38. The method of claim 34 wherein said symmetric key has a key length of at least 128 bits.

39. The method of claim 34 wherein said symmetric key has a key length of at least 192 bits.

40. The method of claim 34 wherein said symmetric key has a key length of at least 256 bits.

41. The method of claim 34 wherein said at least one file characteristic is symmetrically decrypted using an AES decryption decoding.

42. The method of claim 34 wherein said at least one file characteristic is symmetrically decrypted using a 3DES decryption decoding.

43. The method of claim 33 wherein said at least one file characteristic is asymmetrically decrypted.

44. The method of claim 43 wherein said asymmetric decryption employs a private key.

45. The method of claim 43 wherein said asymmetric decryption employs a X.509 digital certificate.

46. The method of claim 33 including a plurality of file characteristics.

47. The method of claim 46 wherein not all of said plurality of file characteristics are decrypted.

48. The method of claim 46 wherein at least one of said plurality of file characteristics is decrypted using a first type of decryption and at least one of said plurality of file characteristics is decrypted using a second type of decryption.

49. The method of claim 48 wherein a first of said plurality of file characteristics is decrypted using a first symmetric decryption and a second of said plurality of file characteristics is decrypted using a second symmetric decryption different from said first symmetric decryption.

50. The method of claim 49 wherein said first symmetric decryption employs a key having a first key length and said second symmetric decryption employs a key having a second key length different from said first key length.

51. The method of claim 48 wherein a first of said plurality of file characteristics is decrypted using a first asymmetric decryption and a second of said plurality of file characteristics is decrypted using a second asymmetric decryption different from said first asymmetric encryption.

52. The method of claim 33 wherein said at least one file characteristic includes the name of said data file.

53. The method of claim 33 wherein said at least one file characteristic includes the size of said data file.

54. The method of claim 33 wherein said at least one file characteristic includes the creation date of said data file

55. The method of claim 33 wherein said at least one file characteristic includes the creation time of said data file.

56. The method of claim 33 further including decrypting said data file.

57. The method of claim 56 wherein said data file is decrypted using symmetric decryption.

58. The method of claim 56 wherein said data file is decrypted using asymmetric decryption.

59. The method of claim 56 further including decompressing said file characteristic after decrypting said file characteristic.

60. The method of claim 59 wherein said data file is decompressed using a Lempel-Ziv (LZ)-type data decompression algorithm.

61. The method of claim 59 wherein said data file is decompressed using a Deflate-type data decompression algorithm.

62. The method of claim 59 wherein said data file is decompressed using a Burrows-Wheeler Transform (BWT)-type data decompression algorithm.

63. The method of claim 57 wherein said data file is not decompressed.

64. The method of claim 33 further including decompressing said file characteristic.

65. The method of claim 33 wherein said data container is constructed in accordance with a .Zip file format.