Method Of Decrypting An Electronic Document For The Safety Management Of The Electronic Document

Abstract

A method of encrypting/decrypting the document and a safety management storage device and system method of its safety management, using for the safety management of electronic documents, the said system comprising a PC or mainframe installed with common reading software and a storage device of safety management connected to the said PC/mainframe through hot-plug; when connected to the mainframe, the said storage device is enumerated as a USB CDROM device at least. The user owns the said storage device can encrypt the electronic documents by using the encryption keys to generate an encrypted document with the same file type, also can open the encrypted document by using common reading software, and then use the document according to the predetermined operation authority.

1 . A method of decrypting an electronic document for the safety management of the electronic document, comprising steps of:
 storing an encrypted electronic document into a storage unit of a PC or mainframe;   finishing installation of a common reading software corresponding to a file type of said electronic document on said PC or mainframe;   connecting a storage device with content of decryption authority to said PC or mainframe;   recognizing, by said PC or mainframe, the storage device, and running automatically a document decryption program which is in said storage device;   taking over automatically, by said document decryption program, a scheduled operation run by said common reading software; and   running said common reading software to open said encrypted electronic document, and operating the electronic document within a predetermined range of the rights.   
     
     
         2 . The method of decrypting the electronic document according to  claim 1  wherein said storage device comprises a USB interface and control unit with its device type set as USB Mass Storage Device such that the PC or mainframe recognizes and enumerates said storage device as a USB CDROM device so that said document decryption program can be run automatically. 
     
     
         3 . The method of decrypting the electronic document according to  claim 1  wherein said taking over automatically step comprises said document decryption program injecting an decryption module into the scheduled program process of said common reading software in the PC or mainframe operation system through a remote thread injection and function hook, so as to take over the scheduled operation ran by said common reading software, and said running step comprises:
 taking over and controlling, by said decryption module, a read operation of said common reading software, while the PC or mainframe is operated to open said encrypted electronic document; 
 reading the data of said encrypted electronic document first; 
 restoring data from said encrypted data by using a decryption key in the decryption module, and reading the scheduled operation authority in the encrypted data; and 
 showing, by said common reading software, the restored data and the operation authority of the electronic document. 
 
     
     
         4 . The method of decrypting the electronic document according to  claim 3  wherein the running step comprises choosing a relevant decryption key according to a key serial number in encryption information of said encrypted data and performing decryption processing in the scheduled process of said common reading software such that the decrypted data is shown by said common reading software directly. 
     
     
         5 . The method of decrypting the electronic document according to  claim 1  wherein said storage device contains authority information for using the electronic document, which is coordinating with scheduled operation authority to limit an operator's usage of the encrypted electronic document.