Method and system for asymmetrically encrypting .ZIP files

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.

1 . A method of placing data in a data container, said method including:
 receiving received data at an application;   encrypting said received data using a symmetric key to form encrypted data using said application, wherein said symmetric key has one of a plurality of available bit lengths;   asymmetrically encrypting said symmetric key to form an encrypted symmetric key;   placing said encrypted data in a data container using said application, wherein said data container is designed for containing compressed files, wherein said data container includes a local record header for said encrypted data; and   placing said encrypted symmetric key in said data container,   wherein said data container includes a central directory record identifying the location of said encrypted data inside said data container,   wherein said data container also includes a local decryption header, wherein said local decryption header includes an identification of the one of said plurality of available bit lengths that was used in said symmetric key to encrypt said encrypted data.   
     
     
         2 . The method of  claim 1  further including:
 compressing said received data before encrypting said received data.   
     
     
         3 . The method of  claim 2  wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm. 
     
     
         4 . The method of  claim 2  wherein said compressing employs a Deflate-type data compression algorithm. 
     
     
         5 . The method of  claim 2  wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm. 
     
     
         6 . The method of  claim 1  wherein said data container is constructed in accordance with a .Zip file format. 
     
     
         7 . The method of  claim 1  further including:
 encrypting said received data without compressing said received data.   
     
     
         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 . A Zip file format data container stored on a computer, said data container including:
 an encrypted data file,   wherein said encrypted data file has been encrypted by an application using symmetric encryption, wherein said symmetric encryption employs a symmetric key having one of a plurality of available bit lengths,   wherein said symmetric key is asymmetrically encrypted to form an encrypted symmetric key,   wherein said data container is designed by an application for containing compressed files,   wherein said data container includes a local record header for said encrypted data   wherein said encrypted symmetric key is placed in said data container,   wherein said data container includes a central directory record identifying the location of said encrypted data file inside said data container,   wherein said central directory record is used to access said encrypted data file in the process of decrypting said encrypted data file,   wherein said data container also includes a local decryption header, wherein said local decryption header includes an identification of the one of said plurality of available bit lengths that was used in said symmetric key to encrypt said symmetric key.   
     
     
         11 . The data container of  claim 10  wherein said encrypted data has been compressed before encryption. 
     
     
         12 . The data container of  claim 11  wherein said encrypted data has been compressed before encryption using a Lempel-Ziv (LZ)-type data compression algorithm. 
     
     
         13 . The data container of  claim 11  wherein said encrypted data has been compressed before encryption using a Deflate-type data compression algorithm. 
     
     
         14 . The data container of  claim 11  wherein said encrypted data has been compressed before encryption using a Burrows-Wheeler Transform (BWT)-type data compression algorithm. 
     
     
         15 . The data container of  claim 10  wherein said encrypted data has not been compressed before encryption. 
     
     
         16 . The data container of  claim 10  wherein said data container is constructed in accordance with a .Zip file format. 
     
     
         17 . The data container of  claim 10  wherein said asymmetric encryption employs a public key. 
     
     
         18 . The data container of  claim 10  wherein said asymmetric encryption employs a X.509 digital certificate.