Computer security system and method

FIELD OF THE INVENTION

[0001] The present invention generally relates to a computer security system and method for securing information such as files stored within the computer system.

BACKGROUND OF THE INVENTION

[0002] A great deal of focus is placed in the prior art on the problem of improving computer security by preventing unauthorized access to a computer system, for example by hackers over a network such as the Internet. This focus does not, however, address the problem of providing security once someone has accessed the computer. For example, within a company, many employees may have access to a computer system but it is necessary to provide a level of security for information on the computer system.

SUMMARY OF THE INVENTION

[0003] The first aspect of the present invention provides a secure method and system for encrypting files in which the content of the files are initially compressed and then encrypted.

[0004] This aspect of the present invention provides for the secure encryption of files since the compression process improves the security by removing potential patterns in the file content which could weaken the strength of the encryption.

[0005] In a preferred embodiment the compression comprises run length encoding of the content of the file.

[0006] In another embodiment the compression includes the identification of a file header in the content of the file and of obfuscation of the file header before encryption. The obfuscation can comprise modifying, moving or deleting the file header.

[0007] In a preferred embodiment the encryption is performed using symmetric key encryption and in one embodiment the encryption key is based on a user input password.

[0008] This aspect of the present invention also includes a method and system for decrypting the content of an encrypted file in which the file content is decrypted and then decompressed.

[0009] Another aspect of the present invention provides a method and system for obfuscating at least one file in a computer system in which a file name of the or each file is automatically changed from an original file name to an obscure file name and the or each file is moved from an original location to at least one obscure location. A record of the or each original file name and location and the or each corresponding obscure file name and location is kept in encrypted form.

[0010] Thus in accordance with this aspect of the present invention files can be obfuscated or hidden by changing their file name and moving them automatically. The new file name is chosen to be obscure, i.e. a non-obvious file name such as a random or pseudo-random file name. Also the location of the files is chosen to be obscure so as to make it less obvious where the files may be should someone attempt to locate and read them.

[0011] In a preferred embodiment the locations comprise directories or folders in a computer system.

[0012] In one embodiment a user can select the or each directory or folder for the obfuscation of files. In one embodiment the user can then select the files for obfuscation. In an alternative embodiment, files within the directory or folder are automatically selected. This selection can be based on file type, e.g. encrypted files, or all files within the folder or directory can be obfuscated automatically.

[0013] This aspect of the present invention also provides a method and apparatus for recovering at least one obfuscated file in a computer system in which a record of at least one original file name and location and at least one corresponding obscure file name and location is read and decrypted. The file name of the or each obfuscated file is then automatically changed from the or each obscure file name to the or each original file name and the or each file is moved from the respective obscure location to the respective original location.

[0014] Thus in this aspect of the present invention, obfuscated files can be recovered.

[0015] In a preferred embodiment a user makes a selection of the or each original directory or folder. This requires the user to remember the or each directory or folder in which the original file was stored. This provides an element of security since it requires the user to remember something. When a user enters the selection, this can be used to identify at least one corresponding obscure file name and directory or folder in the decrypted record. The or each corresponding obscure file name is then automatically changed to the or each original file name and the or each corresponding file is moved from the respective obscure directory or folder to the respective original directory or folder.

[0016] Another aspect of the present invention provides a method and system for obfuscating information stored in a location in a computer system. The information is divided into a plurality of segments and each segment is stored in a new location. A record of the location of the information and corresponding new locations is kept in encrypted form. The original information is then deleted, preferably securely.

[0017] Thus in accordance with this aspect of the present invention, a secure obfuscation method and system is provided since even if an unauthorized person were able to identify a file, this would only represent a segment of the data in the original file.

[0018] In one embodiment to further improve the level of obfuscation, the segments are of random or pseudo-random size. Also, in a preferred embodiment a number of the segments can be inverted, i.e. written backwards, before being stored. In this case the record includes information identifying which segments are stored in inverted form to facilitate the reconstruction of the original information.

[0019] Information to be encrypted can be based on a user selection of the location and of the actual information. Alternatively, the information to be obfuscated can be automatically determined based solely on a user selection of the location of information.

[0020] In a preferred embodiment the information comprises a file having a file name and the location is identified by a directory or folder name. Also the record includes the file name and directory or folder. In this embodiment each segment can be stored as a file having a new file name in another directory or folder and the record can include the new files names and other directories and folders. The file names used for each segment can be randomly or pseudo-randomly generated as an obscure file name and the directory or folder in which each segment is stored can also be an obscure directory or folder, e.g. an operating system directory or program directory.

[0021] In an alternative embodiment of the present invention, the segments are stored in a form which is not recognisable by an operating system. Thus, the segments do not appear in any file menu or file location utility available in the computer operating system.

[0022] In a preferred embodiment to ensure increased security, the information is preferably encrypted before segmentation. The encryption method can, in one embodiment, comprise the encryption method of the first aspect of the present invention.

[0023] This aspect of the present invention enables any number of information items to be obfuscated by individual segmentation. In such a case the record includes the location of each information item and corresponding new locations of stored segments.

[0024] This aspect of the present invention also encompasses a method and system for restoring information obfuscated in a computer system. A record of an original location of the information and corresponding locations of segments of the information is read and decrypted. The segments of the information are read from the locations and combined to form the original information. The original information is then stored as the restored information in the original location.

[0025] Thus this aspect of the present invention encompasses the reverse process of obfuscation for restoration of obfuscated files.

[0026] A further aspect of the present invention provides a method of operating a computer system to provide file security and a computer system for the provision of file security in which a password input interface is generated requiring a password input from a user. An input password is compared with a stored password and a graphical user interface is generated displaying a file menu in dependence upon the comparison to allow a user to input a user selection of at least one file for encryption or decryption. In response to the user selection the or each selected file is encrypted or decrypted using symmetric key encryption or decryption and the input password comprises the basis of the key for encryption or decryption.

[0027] Thus in accordance with this aspect of the present invention a simple user interface is provided by which a user can only gain access to the security graphical user interface by the entry of a password. Once the password is entered a user need not enter a user password again in order to perform encryption/decryption operations. Such operations simply require the user to select files from a file menu.

[0028] In a preferred embodiment the graphical user interface is generated with a selectable option to allow a user to input a user selection of at least one file to be obfuscated and the or each file is obfuscated in response to the user selection. Thus in this embodiment of the present invention, the generated security graphical user interface allows a user to access a secure and simple method of both encrypting and obfuscating files. In this embodiment the graphical user interface can also include a selectable option to allow a user to input a user selection to restore obfuscated files. This selection can simply comprise the selection of a directory or folder in which files were originally contained for obfuscation and the restoration of the files into the original directory or folder will take place automatically.

[0029] A further aspect of the present invention provides a method of assisting an operator of a processing system and a processing system for providing operator assistance in which user inputs to the processing system are monitored during processing of a file by a processing application. The detection of when a processing application has finished processing a file takes place and at this point monitored user inputs are compared to a user profile. The user interface is generated in dependence upon the comparison to allow the user to select to encrypt the file. If a user selects to encrypt the file, the file is automatically encrypted.

[0030] Thus in accordance with this aspect of the present invention, a user is assisted or prompted to securely store files after processing of the files. This is achieved by monitoring user inputs and comparing these with a user profile.

[0031] In a preferred embodiment the monitored user inputs comprise key strokes and the comparison comprises comparing the monitored key strokes with words in the user profile.

[0032] The user profile can contain information on previous behaviour of a user such as keywords related to files that a user has previously encrypted. Thus, in other words, it determines an encryption behaviour for a user. Thus by monitoring the previous encryption selections it is possible to modify the user profile in accordance with the previous encryption behaviour of the user.

[0033] Any aspect of the present invention described hereinabove can be used in conjunction with any other aspect of the present invention to provide a secure processing system for a user.

[0034] The present invention can be implemented solely in hardware, in software controlling a general-purpose computer, or in a combination of specially configured hardware and software controlling programmable hardware. The present invention thus encompasses computer program code for controlling the processing system to implement the method of the present invention. The computer program code can be provided to the processing system on any suitable carrier medium such as a storage medium, e.g. a floppy disk, hard disk, CD-ROM, programmable memory device, or magnetic tape device, or a transient medium such as an electrical, optical, microwave, acoustic, or magnetic signal, e.g. a signal carrying computer code over a computer network such as the Internet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 is a screen shot of a user interface for registering a user in accordance with an embodiment of the present invention;

[0036]FIG. 2 is a screen shot of the user interface for logging in to enter a user password in accordance with an embodiment of the present invention;

[0037]FIG. 3 is a screen shot of the user interface showing the file menu and the security options in accordance with an embodiment of the present invention;

[0038]FIG. 4 is a schematic diagram of a secure processing system in accordance with an embodiment of the present invention;

[0039]FIG. 5 is a screen shot of a graphical user interface showing the selection of files in the file menu for encryption of the files in accordance with an embodiment of the present invention;

[0040]FIG. 6 is a screen shot showing the interface following encryption of the files in accordance with an embodiment of the present invention;

[0041]FIG. 7 is a flow diagram illustrating the encryption process in accordance with an embodiment of the present invention;

[0042]FIG. 8 is a flow diagram illustrating the decryption process in accordance with an embodiment of the present invention;

[0043]FIG. 9 is a flow diagram illustrating a first stealth method in accordance with an embodiment of the present invention;

[0044]FIG. 10 is a flow diagram illustrating a first stealth restoration method in accordance with an embodiment of the present invention;

[0045]FIG. 11 is a flow diagram illustrating a second stealth method in accordance with an embodiment of the present invention;

[0046]FIG. 12 is a flow diagram illustrating a second stealth restoration method in accordance with an embodiment of the present invention; and

[0047]FIG. 13 is a flow diagram illustrating the monitoring process in accordance with an embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0048]FIG. 1 illustrates a graphical user interface which is displayed when security software in accordance with an embodiment of the present invention is installed on a computer. The graphical user interface allows a user to enter their pass phrase, i.e. a sequence of passwords. In this embodiment of the present invention a pass phrase is used as the password rather than a single word password since the increased number of characters increases security.

[0049] The graphical user interface also allows the level of the user to be selected. A master user can be the default user when the software is first installed on a computer. The software can subsequently allow a number of installations on other computers whereupon users become sub-users. The master user can then have access to the pass phrases for these users to allow them access to files which have been secured using the security application as will be described in more detail hereinafter.

[0050] Once the security application has been installed, when a user wishes to execute the application, a log-in window is initially displayed as illustrated in FIG. 2. The log-in window requires a user to enter their name and pass phrase in order to open the security application. The user name and pass phrase are those entered by the user when installing the application and these are securely stored by the application so that a user can be authenticated. Thus a user can only access the security application user interface as illustrated in FIG. 3 by entering a pass phrase.

[0051] The graphical user interface illustrated in FIG. 3 is the user interface to security features provided by the security application. At the centre of the graphical user interface there is displayed a file menu window <b>1</b> which comprises a drive list section <b>2</b>, a directory or folder list section <b>3</b> and a file list section <b>4</b>. This type of file menu is conventional in Microsoft Windows (trade mark) type applications. A user is thus able to select files in various locations for security operations. A security interface, for example, enables a user to select using the scan button <b>5</b> to scan a directory or folder or disk drive for unauthorized material. A user can also select the clean button <b>6</b> when a disk drive is selected in the drive list window <b>2</b> to clean a hard disk, i.e. by removing temporary files, marking damaged clusters, etc. A user can also select the shred button <b>7</b> to shred files selected in the file window <b>4</b>. The shred operation performs secure deletion by multiple overwrites of the sections of the hard disk on which the files are stored. A user can also select the vault button <b>8</b> to access a secure backup storage system at a server. The features provided by buttons <b>5</b> to <b>8</b> are not essential features for the present invention and merely provide additional utilities available from the graphical user interface provided by the security application.

[0052] The graphical user interface includes an encrypt button <b>10</b> and a decrypt button <b>9</b>. When files are selected in the file window <b>4</b> the selected files will be encrypted or decrypted as appropriate.

[0053] The graphical user interface also provides an apply stealth button <b>11</b> and a remove stealth button <b>12</b>. When these buttons are selected and a directory or folder is selected in the directory or folder window <b>3</b>, files are “stealthed” or recovered in the selected directory. The stealth operation obfuscates or hides the files of a certain type that are contained in the selected directory. In this embodiment the files that are automatically selected for hiding or obfuscating in the selected directory are encrypted files. Thus in this embodiment only encrypted files are hidden. Thus the stealth operation provides a further level of security for files which are deemed to be sufficiently important to require encryption.

[0054] Although in this embodiment only encrypted files are obfuscated by the stealth operation, the present invention encompasses the obfuscation of any type of file. For example, the stealth process could automatically obfuscate all files in the selected directory or only files of a certain type. The file type need not require that the files be encrypted.

[0055] In order to recover files a user must remember and select the directory or folder that originally contained the obfuscated files using the folder or directory window <b>3</b>. The user can then select the remove stealth button <b>12</b> and the files are automatically recovered.

[0056]FIG. 4 is a schematic diagram of a security processing system in accordance with an embodiment of the present invention. In this embodiment of the present invention the security processing system comprises a suitably programmed general-purpose computer. The computer is provided with a network interface <b>20</b> to allow access to other computer systems. A pointing device <b>23</b>, display <b>21</b> and keyboard <b>22</b> are provided to allow display of the graphical user interface and interaction by the user with the graphical user interface. A processor <b>24</b> is provided for reading and executing code stored in a program memory <b>25</b>. The program memory <b>25</b> holds code being executed by the processor <b>24</b>. The program memory <b>25</b> thus comprises volatile memory and stores code for providing the various functions of the security application. In this embodiment the code comprises interface face for generating the graphical user interface, stealth code for performing the obfuscation (stealth) process, encryption code for performing the encryption and decryption process, file manipulation code for performing file manipulation when a user selects the files within the file menu <b>1</b>, artificial intelligence code for updating the user profiles, and monitoring program code for performing the monitoring operation to assist a user in securely storing files (as will be described in more detail hereinafter).

[0057] A data memory <b>26</b> is provided to store data being used by the processor <b>24</b> when executing the program code and program memory <b>25</b>. The data memory holds the password, a unique key for the security application to be used for encrypting the record for stealth (obfuscated) files, key stroke history and user profile data.

[0058] A hard disk <b>28</b> is provided as a non volatile store to store the security application code which is loaded into the program memory <b>25</b>, the monitoring application code which is also loaded into the program memory <b>25</b> for execution by the processor <b>24</b>, application data files which include the password data, user profile data and unique key data, user files e.g. documents, spreadsheets etc, encrypted files, stealth files and the hidden locator files i.e. the stealth record file.

[0059] The operation of the security application in the computer will now be described.

[0060]FIG. 5 is a screen shot of the graphical user interface showing the selection of four files under the directory “MY DOCUMENTS”. FIG. 5 also illustrates the selection of the encrypt button <b>10</b> as a result of the user requiring the encryption for these four selected files.

[0061]FIG. 6 is a screen shot illustrating the result of the encryption process. The four files are encrypted and given an additional file name extension .ENC. The encrypted files overwrite the original files and so there is thus no excess to the original information.

[0062] The encryption process will now be described with reference to the flow diagram of FIG. 7.

[0063] When the security application is initialised (step S<b>1</b>), the encryption process awaits the selection of the encrypt key <b>10</b> (step S<b>2</b>). When the user selects the encrypt key <b>10</b>, the content of the selected file or files is read (step S<b>3</b>) and the file header in the file is identified and hidden (step S<b>4</b>). This hiding or obfuscation of the file header is important since it represents a recognisable pattern in a file. The file header can be modified in a known way, moved to another part of the file, or deleted. The modified file then undergoes run length compression (step S<b>5</b>). Run length compression is a technique well known in the art of video compression. Run length compression comprises identifying a number of consecutive data items in the data file which are identical or at least similar within certain bounds. Run length compression then comprises representing the consecutive data items i.e. the run by parameters indicating the parameter value and a number of data items, i.e. the run length. The run length compression technique is particularly useful for removing nulls in the data. Such recognisable patterns are a weakness in an encrypted file. Following compression of the file, the file is encrypted using the password (i.e. the pass phrase) as the key (step S<b>6</b>). Steps S<b>4</b>, S<b>5</b> and S<b>6</b> are repeated on a file by file basis on all the files until they are encrypted and the process then returns to step S<b>2</b> to await selection of the encrypt key <b>10</b> again.

[0064] Thus this embodiment of the present invention provides a secure encryption process by which a compression process is carried out initially in order to remove recognisable patterns in the data before encryption. Although in this embodiment run length encoding is used, any sort of compression technique can be used as is well known in the video compression art. The additional modifications to the file header further enhance security.

[0065]FIG. 8 is a flow diagram illustrating the decryption process which is the reverse of the encryption process. When the security application is initialised (step S<b>10</b>), the decryption process awaits selection of the decrypt button <b>9</b> by the user (step S<b>11</b>). When the decrypt button <b>9</b> is selected (step S<b>11</b>), the files selected by the user are read (step S<b>12</b>) and on a file by file basis, each file is decrypted using the password (i.e. pass phrase) as the key (step S<b>13</b>) and the decrypted content is run length decompressed (step S<b>14</b>). Finally, the file header is restored (step S<b>15</b>) and the file is thus restored.

[0066] The method of applying and removing stealth in accordance with one embodiment of the present invention will now be described with reference to the flow diagrams of FIGS. 9 and 10.

[0067]FIG. 9 is a flow diagram illustrating a method of applying stealth, i.e. obfuscating files in accordance with the first embodiment of the present invention. Once the security application has been initialized (step S<b>20</b>) the stealth process awaits selection of the apply stealth button <b>11</b> (step S<b>21</b>). When a user selects the apply stealth button (step S<b>21</b>) encrypted files in the currently selected directory are identified (step S<b>22</b>). These files can be identified by simply looking for the file extension .ENC. The process then generates a random file name for each file to be stealthed (step S<b>23</b>). Also, a directory is determined for storing each of the files (step S<b>24</b>). The directory can comprise any obscure directory such as an operating system directory, or a program directory. The intention is to store the files with a name which is obscure in program or operating system files which frequently have obscure file names so as to obfuscate the file. Each file is then renamed and moved to the determined directories as stealth files (step S<b>25</b>). In order to keep a record of the location of stealthed (obfuscated) files, a hidden location file is opened in a selected directory and entries are made to list the stealth file names, the directories, the original file names and the current directory (step S<b>26</b>). This information can be entered as plain text. The content of the hidden location file is then encrypted (step S<b>27</b>) and the file manipulation interface, i.e. the file menu <b>1</b> is updated to show that the original files are no longer in the original directory (step S<b>28</b>). The encryption is performed using an encryption key which is generated during the installation of the security application. The security application generates a unique key by detecting unique parameters of the computer such as the hard disk serial number. This is used to generate a unique key for encryption. This unique key can either be stored for future encryption/decryption, or more securely, it can be dynamically generated each time encryption and decryption is required of the hidden location file. The hidden location file can be stored as any file name which is similar to an operating system file name and it is preferably stored in an operating system directory so as to obfuscate the file.

[0068] Thus in accordance with this embodiment of the present invention the files can be hidden by moving them and storing them in an obscure directory with an obscure file name. A secure record is kept in encrypted form, once again in an obscure file name in an obscure location, to enable the restoration of the original files in the original directory.

[0069] The process of restoration of the original files in the original directory will now be described with reference to FIG. 10. When the security application is initialized (step S<b>30</b>) the removed stealth process awaits selection of the remove stealth button <b>12</b> by the user (step S<b>31</b>). When a user selects the remove stealth button (step S<b>31</b>) the hidden location file is read and decrypted. The decryption of the hidden location file requires the unique key for the security application. This can either be read from memory if stored, or dynamically generated based on unique hardware parameters such as hard disk serial number. Once the hidden location file has been decrypted, the file names of the stealth files are identified by using the name of the current directory to look up stealth files for the current directory (step S<b>32</b>). If there is no entry in the hidden location file for the current directory (step S<b>33</b>) a message is displayed in the graphical user interface to inform the user there are no hidden (stealthed) files (step S<b>34</b>) and the process returns to step S<b>31</b> to await a user selection of the remove stealth button <b>12</b>. If there are entries for the current directory in the hidden location file (step S<b>33</b>) the stealth files are renamed with the original files names which are also stored in the hidden location file and the files are moved back to the current directory (step S<b>35</b>). The data for the current directory in the hidden location file is then deleted and if the hidden location file is empty, i.e. it is the only stealth file having a record in the hidden location file, the hidden location file is securely deleted, i.e. by repeatedly overwriting the storage location on the hard disk (step S<b>36</b>). The file manipulation interface, i.e. the file menu <b>1</b> in the graphical user interface is then updated (step S<b>37</b>) to show that the original files are now returned to the original directory.

[0070] Thus the apply stealth and remove stealth process removes the files from being visible in the current directory and returns them to be invisible respectively.

[0071] A second method of applying and removing stealth will now be described with reference to the flow diagrams of FIGS. 11 and 12. In this embodiment of the present invention stealth files comprise segments of the original file. The segments are stored in obscure locations, i.e. obscure directories or folders.

[0072]FIG. 11 is a flow diagram illustrating the process for applying stealth in accordance with this embodiment of the present invention. When the security application is initialized (step S<b>40</b>) the stealth process awaits selection of the apply stealth button <b>11</b> by the user (step S<b>41</b>). When a user selects the apply stealth button <b>11</b> (step S<b>41</b>) encrypted files in the current directory are identified (step S<b>42</b>). In this embodiment the encrypted files are identified by identifying all files with the file extension .ENC. The process then generates a number of random file names (step S<b>43</b>). These file names comprise obscure file names that would not indicate the content of the file. The process then determines a number of directories for storing files (step S<b>44</b>). Random chunks of file content are then taken and some of these chunks are inverted before being written to stealth files. The stealth files are given the generated random file names in the determined directories (step S<b>45</b>). A number of hidden location files are opened in a number of selected directories and these store the list of stealth file names, directories, original file names and the current directory (step S<b>46</b>). A single hidden location file can be generated to store the necessary information. The information will include the identity of the chunks that have been inverted so that the original file can be correctly reconstructed. Alternatively, a plurality of location files can be generated, some of them containing spoof data. If more than one hidden location file contains data, a master hidden location file will contain the location of the other hidden location files. The hidden location files are then encrypted (step S<b>47</b>). If there is only one encryption file this can be encrypted using a unique key which can either be stored following generation during the installation of the security application, or the key can be generated dynamically from unique hardware parameters such as the hard disk serial number. If there is more than one hidden location file, the master hidden location file can be encrypted using this unique key, and the content of the master hidden location file will include the key or half of the key for decrypting each of the other hidden location files. Each of the other hidden location files can thus contain half of the encryption key. Thus in order to remove stealth it will be necessary to decrypt each of the hidden location files using-the respective keys. This will be described in more detail with reference to the flow diagram of FIG. 12.

[0073] Following encryption of the hidden location files the original files in the current directory are securely deleted (step S<b>48</b>) and the file manipulation interface, i.e. the file menu <b>1</b> in the graphical user interface is updated (step S<b>49</b>).

[0074] The process for restoring the files by removing stealth will now be described with reference to the flow diagram of FIG. 12.

[0075] Following initialization of the security application (step S<b>50</b>) the remove stealth process awaits selection of the remove stealth button <b>12</b> by the user (step S<b>51</b>). When a user selects the remove stealth button <b>12</b> (step S<b>51</b>) the hidden location files are read and decrypted. If there is a single hidden location file, this is read and decrypted using the unique key for the security application. The unique key can be read from a secure storage location where it is stored following installation of the application, or it can be dynamically generated from unique information identifying the hardware, such as a hard disk serial number. If there is more than one hidden location file, following decryption of the master hidden location file, the content of the master hidden location file will identify the location of the other hidden location files and can include half of the encryption key necessary to decrypt them. A separate key can be used for hidden location file. Thus it is necessary to locate and read the other location files in order to accumulate all the information to restore the original files. Once all of the information has been retrieved by reading and decrypting the hidden location files, the file names of stealth files are identified using the name of the current directory. The current directory points to original file names which were stored in the current directory, file sizes, the file names of the stealth files generated for the original files, the directories in which the stealth files were stored, and information identifying whether any of the stealth files include inverted chunks of data.

[0076] If no entry is identified in the hidden location files for the current directory (step S<b>53</b>) a message is displayed in the graphical user interface to indicate to the user that there are no hidden files, i.e. no stealth files (step S<b>54</b>) and the process returns to step S<b>51</b> to await the selection of the remove stealth button <b>12</b> by the user. If there are entries in the hidden location files for the current directory (step S<b>53</b>) the stealth file contents are read and on a file-by-file basis original files are constructed from the read chunks. Where necessary, the chunks are reinverted based on the information contained in the hidden location files (step S<b>55</b>). Data in the hidden location files for the current directory is then deleted and if this is the only entry in the hidden data files they are securely deleted (step S<b>56</b>). The stealth files are then securely deleted (step S<b>57</b>) and the file manipulation interface (i.e. the file menu <b>1</b>) is updated (step S<b>58</b>) to show the return of the original files to the current directory. The process then returns to step S<b>51</b>) to await selection of the remove stealth button <b>12</b> by the user.

[0077] It can thus be seen that in this embodiment of the present invention an additional level of security is provided by not just using obscure file names and obscure directories in which to store the files, but also by segmenting the files in random chunks and distributing these across directories, it makes it further difficult for unauthorized access to the content of these files.

[0078] It can thus be seen from the foregoing description that the graphical user interface provided by the security application provides simply means by which a user can enter a user password and perform secure operations on files simply by selecting files and without having to enter in a password or pass phrase each time. The operation of accessing the graphical user interface of the security application by entry of the password provides access to the full functionality of encryption and obfuscation or stealthing of files without requiring tiresome entry of passwords each time. Thus the graphical user interface provides a simple security interface for a user of the security system.

[0079] The method of assisting the user of a processing system to assist in secure storage of data will now be described with reference to the flow diagram of FIG. 13.

[0080] In this embodiment of the present invention a separate monitoring application is provided for providing this function. It can however be incorporated into the security application described hereinabove.

[0081] When the monitoring application is initialized (step S<b>60</b>) it continuously records keystrokes entered by a user during the processing of a file by an application (step S<b>61</b>). For example, when using a word processing application, a user will type in text and this is recorded. A monitoring application monitors applications into text when application close files (step S<b>62</b>), i.e. when an application finishes processing the file. When it is detected that an application has finished processing a file (step S<b>62</b>) the recorded keystrokes are compared to a stored user profile (step S<b>63</b>). The user profile can include keywords which have been stored for previous documents for which a user has requested encryption for security purposes. This comparison is performed by an artificial intelligence program. If there is no match between the recorded keystrokes and the stored user profile (step S<b>64</b>) the process returns to recording keystrokes (step S<b>61</b>) when a next application processes a file. If a match is found the graphical user interface generates a message asking the user if they want to secure the file, i.e. encrypt it (step S<b>65</b>). If a user selects not to secure the file (step S<b>66</b>) the artificial intelligence application records this selection and modifies the user profile accordingly (step S<b>67</b>) and the process returns to step S<b>61</b> to record keystrokes in the next processing of a file by an application. Thus the artificial intelligence application is able to modify the user profile in accordance with previous user security history.

[0082] If a user selects to secure the file (step S<b>66</b>) the security application is launched and the file name of the file is passed to the security application together with the directory name (step S<b>68</b>). Within the security application, a user is required to enter their pass phrase (password) (step S<b>69</b>) and if successfully input, the security application will encrypt the file (step S<b>70</b>). The artificial intelligence application will then record the user selection in the user profile (step S<b>71</b>) in order to modify the encryption history for the user.

[0083] Thus in this embodiment of the present invention, a user can be prompted to securely store files such as documents after finishing processing on the document. This can avoid the unintentional security lapses by users i.e. by a user forgetting to encrypt a file with sensitive content.

[0084] Although the present invention has been described hereinabove with reference to specific embodiments, it will be apparent to a skilled person in the art that the modifications lie within the spirit and scope of the present invention.

[0085] In accordance with the present invention, the use of a password can comprise any string of alphanumeric characters. The string is preferably long to increase security and thus in the embodiments described hereinabove a pass phrase is used. It will thus be understood by a skilled person in the art that the term password encompasses pass phrase.