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

• US 20050086475A1
• Filed: 09/20/2004
• Published: 04/21/2005
• Est. Priority Date: 07/16/2003
• Status: Abandoned Application

• Current Assignee: PKWARE, Inc. (PKW Holdings, Inc.)
• Original Assignee: PKWARE, Inc. (PKW Holdings, Inc.)
• Inventors: Peterson, James C.
• Application Number:
  US10/946,271
• Publication Number:
  US 20050086475A1
• Time in Patent Office: Days
• US Class Current: 713/170
• 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 data 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;

symmetric key data;

asymmetric key data; and

an encrypted data file,

wherein said symmetric key data is derived from a symmetric key used to symmetrically encrypt a data file to form said encrypted data file,

wherein said asymmetric key data is derived from an asymmetric encryption performed on said symmetric key data;

receiving a decryption key input; and

providing the option of;

using said asymmetric key data in combination with said decryption key input to recover said symmetric key to symmetrically decrypt said encrypted data file to form a decrypted data file when said decryption key input is a desired asymmetric key; and

using said symmetric key data in combination with said decryption key input to recover said symmetric key to symmetrically decrypt said encrypted data file to form a decrypted data file when said decryption key input is a desired symmetric key; and

providing access to said decrypted data file.

2. The method of claim 1 further including decompressing said decrypted data file.

3. The method of claim 2 wherein said decompressing employs a Lempel-Ziv (LZ)-type data compression algorithm.

4. The method of claim 2 wherein said decompressing employs a Deflate-type data compression algorithm.

5. The method of claim 2 wherein said decompressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.

6. The method of claim 1 wherein said encrypted data file is not compressed.

7. The method of claim 1 wherein said symmetric key has a key length of at least 128 bits.

8. The method of claim 1 wherein said symmetric key has a key length of at least 192 bits.

9. The method of claim 1 wherein said symmetric key has a key length of at least 256 bits.

10. The method of claim 1 wherein said symmetrically decrypting employs an AES encryption encoding.

11. The method of claim 1 wherein said symmetrically decrypting employs a 3DES encryption encoding.

12. The method of claim 1 wherein said asymmetrically decrypting employs a private key.

13. The method of claim 1 wherein said asymmetrically decrypting employs a X.509 digital certificate.

14. The method of claim 1 wherein at least part of said decryption key is externally input.

15. The method of claim 14 wherein said at least part of said decryption key is a password.

16. The method of claim 14 wherein said at least part of said decryption key is a private key.

17. The method of claim 14 wherein at least part of said symmetric key is composed of random data.

18. A method of providing access to data in a data container, said method including:

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

symmetric key data;

asymmetric key data; and

an encrypted data file,

wherein said symmetric key data is derived from a symmetric key used to symmetrically encrypt a data file to form said encrypted data file,

wherein said asymmetric key data is derived from an asymmetric encryption performed on said symmetric key data;

receiving a decryption key input; and

providing the option of;

using said asymmetric key data in combination with said decryption key input to recover said symmetric key to symmetrically decrypt said encrypted data file to form a decrypted data file when said decryption key input is a desired asymmetric key input; and

using said symmetric key data in combination with said decryption key input to recover said symmetric key to symmetrically decrypt said encrypted data file to form a decrypted data file when said decryption key input is a desired symmetric key input; and

providing access to said decrypted data file.

19. The method of claim 18 further including decompressing said decrypted data file.

20. The method of claim 19 wherein said decompressing employs a Lempel-Ziv (LZ)-type data compression algorithm.

21. The method of claim 19 wherein said decompressing employs a Deflate-type data compression algorithm.

22. The method of claim 19 wherein said decompressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.

23. The method of claim 18 wherein said encrypted data file is not compressed.

24. The method of claim 18 wherein said symmetric key has a key length of at least 128 bits.

25. The method of claim 18 wherein said symmetric key has a key length of at least 192 bits.

26. The method of claim 18 wherein said symmetric key has a key length of at least 256 bits.

27. The method of claim 18 wherein said symmetrically decrypting employs an AES encryption encoding.

28. The method of claim 18 wherein said symmetrically decrypting employs a 3DES encryption encoding.

29. The method of claim 18 wherein said asymmetrically decrypting employs a private key.

30. The method of claim 18 wherein said asymmetrically decrypting employs a X.509 digital certificate.

31. The method of claim 18 wherein at least part of said decryption key is externally input.

32. The method of claim 31 wherein said at least part of said decryption key is a password.

33. The method of claim 31 wherein said at least part of said decryption key is a private key.

34. The method of claim 31 wherein at least part of said symmetric key is composed of random data.

35. The method of claim 18 wherein said data container is constructed in accordance with a .Zip file format.