Abstract:
A file protection method. At least one file attached to an e-mail is retrieved. An executable file including the attached file is automatically generated. The file attached to the e-mail is automatically replaced by the executable file. The e-mail is transmitted to a destination terminal. When executed, the executable file determines whether to display the attached file based on transmission of the destination terminal identification to a predetermined server.

Description:
BACKGROUND  
       [0001]     The invention relates to computer techniques, and in particular, to data protection.  
         [0002]     Since e-mails are widely used in business transactions, various documents including confidential files are exchanged thereby. Even if addressees are limited to a specified group, e-mails as well as files therein may be forwarded to others.  
         [0003]     Document protection typically uses cryptographic techniques. Thus, only recipient computers with a corresponding key can open encrypted e-mail attachments. Encrypted data is first decrypted before being opened by a corresponding application. Once encrypted data is decrypted to plain data, duplication or distribution thereof may be easily performed. For example, the plain data or a portion thereof may be copied or saved to another file utilizing corresponding functions of the application and forwarded to others.  
         [0004]     Additionally, when e-mails with attached files are received, no license agreement is set before the attached files are made available, making prosecution against an infringer difficult.  
       SUMMARY  
       [0005]     Accordingly, file protection methods and systems are provided.  
         [0006]     An exemplary embodiment of a file protection method is implemented in a computer. At least one file attached to an e-mail is retrieved. An executable file including the attached file is automatically generated. The file attached to the e-mail is automatically replaced by the executable file. The e-mail is transmitted to a destination terminal. When executed, the executable file determines whether to display the attached file based on transmission of the destination terminal identification to a predetermined server.  
         [0007]     An exemplary embodiment of a file protection method is implemented in a computer. At least one file attached to an e-mail is retrieved. An executable file including the attached file is automatically generated. When opening, the attached file requires an application for processing content thereof. The file attached to the e-mail is automatically replaced by the executable file. When executed, rather than launching the application, the executable file displays the content of the attached file utilizing essential component objects to perform display functions of the application. The executable file prevents implementation of other functions of the application for the file.  
         [0008]     An exemplary embodiment of a file protection system comprises a communication interface and a file converter. The communication interface retrieves at least one file attached to an e-mail. The file converter automatically generates an executable file including the attached file and automatically replaces the attached file with the executable file. The communication interface transmits the e-mail to a destination terminal. When executed, the executable file determines whether to display the attached file based on transmission of the destination terminal identification to a predetermined server. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0009]     The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
         [0010]      FIG. 1  is a block diagram of a network.  
         [0011]      FIG. 2  is a schematic view of an exemplary embodiment of an email and a file protection system.  
         [0012]      FIG. 3  is a flowchart of an exemplary embodiment of a file protection method.  
         [0013]      FIG. 4  is a schematic diagram of an exemplary embodiment of an email converted by the file protection system.  
         [0014]      FIG. 5  is a schematic diagram of an exemplary embodiment of a message comprising a license agreement for attached files.  
         [0015]      FIG. 6  is a schematic diagram of an exemplary embodiment of a menu comprising options for displaying attached files.  
         [0016]      FIG. 7  is a schematic diagram of an exemplary embodiment of a storage medium implementing a file protection method. 
     
    
     DETAILED DESCRIPTION  
       [0017]     File protection methods and systems are provided.  
         [0018]     In  FIG. 1 , computers  9  and  10 , gateway  11 , registry server  12 , and mail server  13  are coupled to network  15 . Gateway  11  is coupled to terminal  14  through network  16 . Networks  15  and  16  may respectively comprise a local area network (LAN) and the Internet. Note that configuration of these entities in  FIG. 1  may be modified.  
         [0019]     Mail server  13  comprises system  30  implementing a file protection method. Computer  9  composes email  20  to-be sent to a group of recipients and attaches files thereto. For example, email  20  is to be sent to computer  10  and terminal  14 . Terminal  14  may be a personal computer, server, cell phone, pager, personal digital assistant (PDA), or laptop.  
         [0020]     With reference to  FIG. 2 , email  20  comprises attachment  21 , including files  22 ˜ 24  which may respectively conform to different data formats and require different corresponding applications when opened. For example, files  22 ˜ 24  may be various documents or images with extensions of .doc, .ppt, .pdf, .jpg, .bmp, gif, tif, or others.  
         [0021]     With reference to  FIGS. 1 and 2 , when submitted from computer  9 , email  20  is routed to mail server  13 . Server  13  receives and stores email  20  (step S 2 ). Communication interface  31  in system  30  retrieves email  20  (step S 4 ). File converter  32  automatically extracts files  22 ˜ 24  and makes executable file  41  (shown in  FIG. 4 ) therefrom (step S 6 ). For each of the files  22 ˜ 24 , checksum generator  33  calculates a checksum thereof utilizing a particular algorithm and embeds the checksum in the file (step S 7 ). The checksum helps in identifying the owner of the files.  
         [0022]     With reference to  FIG. 4 , executable file  41  comprises files  22 ˜ 24  and container  42  for displaying content of files  22 ˜ 24  utilizing the display functions of the corresponding applications thereof. File converter  32  automatically generates email  40  and attaches executable file  41  thereto (step S 8 ).  
         [0023]     Several methods can be utilized to generate email  40 . For example, file converter  32  may automatically substitute attachment  21  in email  20  by executable file  41  to transform email  20  into email  40 . Alternatively, file converter  32  may automatically extract and write content of email  20  to a new email attached with executable file  41  to generate email  40 .  
         [0024]     Communication interface  31  transmits e-mail  40  to the group of recipients (such as computer  10  and terminal  14 ). For example, terminal  14  receives email  40  (step S 10 ) and executes executable file  41 . Executable file  41  automatically displays a license agreement message for files  22 ˜ 24 , indicating that recipient identification and use history of the attached files are to be submitted (step S 12 ). For example, content of message  50  in  FIG. 5  is as the following:  
         [0025]     “The attached files are confidential data of company A, which are only open to intended users. Duplication and distribution thereof is not allowable. If you continue to open these files, identification of your computer and use history of these files will be sent to company A. If you agree, please select the “Accept”-button. If not, please select the “Reject” button.” 
         [0026]     Executable file  41  provides control buttons  51  and  52  corresponding to agree and disagree for message  50 , and triggering corresponding signals when selected.  
         [0027]     Executable file  41  receives a corresponding signal (step S 14 ) and determines which button is selected (step S 16 ). Upon receiving a signal corresponding to the “Reject” button, executable file  41  is terminated. Upon receiving a signal corresponding to the “Accept” button, executable file  41  displays menu  60  with entries  61 ˜ 63  corresponding to files  22 ˜ 24 , as shown in  FIG. 6  (step S 18 ). When an entry (such as entry  61 ) is selected (step S 20 ), executable file  41  automatically transmits the recipient identification, access time, the file name, and a checksum of a file (such as file  22 ) corresponding to the entry to the predetermined registry server  12  (step S 22 ). The recipient identification may comprise Internet Protocol (IP) addresses extracted from email  40  by executable file  41 , media access control (MAC), a combination thereof, or others.  
         [0028]     Executable file  41  determines if the transmission is successfully completed (step S 24 ). If not, executable file  41  determines if the transmission time exceeds a threshold number or a predetermined time (step S 25 ). If so, executable file  41  is terminated. If not, executable file  41  performs step S 24  again.  
         [0029]     As shown in  FIG. 6 , if the transmission is successfully completed, executable file  41  displays container  42  with content of the corresponding file (such as file  22 ) therein. Rather than launching a corresponding application required to process content of the file, container  42  displays the content of the file in container  42  utilizing the essential component objects of the corresponding application and prevents implementation of other functions thereof, such as copy, print, and save operations (step S 26 ).  
         [0030]     The essential component objects may be embedded in executable file  41  in advance by file converter  32 . Alternatively, executable file  41  can invoke essential component objects stored on the recipient host, a remote server, or others. Executable file  41  blocks commands duplicating the opened file to prevent the commands from being granted.  
         [0031]     Registry server  12  receives the recipient identification, access time, file name, and the checksum  10  from the terminal  14  and stores the data in storage unit  121  coupled thereto. Thus, registry server  12  records and traces access to files  22 ˜ 24 . Registry server  12  may comprises a database storing identification of authorized recipients, automatically determine if a recipient using attached files is authorized by comparing received recipient identification with records of the database, and issues an alert when the recipient is unauthorized.  
         [0032]     Mail server  13  receives e-mails from source terminals within network  15  and automatically performs the file protection method for each of the e-mails. Note that conversion of email attachments can be implemented in other entities. For example, a computer may perform a similar file protection method on e-mails or files before transmission thereof. For example, computer  9  may comprise system  30  and convert email  20  to email  40  before delivery thereof through network  15 .  
         [0033]     The file protection system can be implemented in computer programs or electronic circuits. For example, the file protection system is implemented in computer program  72  in  FIG. 7 , executable by central processing unit (CPU)  70  and stored in memory  71 . When loaded into a computer  700 , the file protection system directs the computer to perform a file protection method. Checksum generator  73  generates checksum of attached files. Communication interface  74  receives and transmits emails. File converter  75  converts attached files into an executable file performing the described steps.  
         [0034]     In conclusion, when opening files attached to an email, a recipient terminal automatically determines whether to display the files based on transmission of the recipient terminal identification, file names, access time, file checksum and other information to a predetermined registry server. Use of attached files can be traced and well managed utilizing the predetermined registry server.  
         [0035]     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.