Many people have some data that they would rather not show to others - passwords, personal data, self-written poems, the list can be continued forever. probably you have stored some of this information on your PC where it is conveniently at your reach, but when the time comes to remove the information from your disk, things get a little bit more complicated and keeping your privacy is not as easy as it may have seemed at first. Normal file and folder deletion is insecure Your first thought may be that when you delete file or folder, the data is gone. But, when you delete a file, the operating system does not really remove the files from the disk; it only removes the reference of the file from the file system table. The data remains on the disk as long as another file overwrites it, and even after that, it might be possible to recover files by studying the magnetic fields on the disk platter surface. Before the file is overwritten, anyone can without problems view it with a disk maintenance or an undelete tool. For instance, imagine that you have been browse the Internet for a while and then want to delete any traces revealing what sites you visited. You go to your browser's settings and select to delete the cache and the history file, the information is now gone you think to yourself - well think again. The browser cache files can without problems be restored with an undelete utility and your privacy is once again compromised. To be sure that a file is gone, it must be accurately overwritten before deleting. As simple as it sounds, there are several difficulties in secure files removal, mostly caused by the construction of a HDD and the use of data encoding. These troubles have been taken into account when special eraser utility is designed and because this special design you can safely and easily remove private information from the hard driver. You have likely already insecurely erased big amount of files from the HDD and every now and then programs create (and insecurely delete) temporary files on your HDD containing some probably private data that you would rather not show to other people. This information remains on the hard driver until it gets overwritten and can be retrieved with simple disk software. This is where the erasing of free hard driver space comes in handy. The erasing of free HDD space means that all free space on your disk will be overwritten so that files previously stored on it cannot be retrieved. Good eraser software provides you a handy way to erase the unused hard disk space regularly in order to erase the all temporary files and other sensitive information you likely have had on your disk. You must be wondering what this application does to my system when erasing files. You have come to the right place, the procedures gone through when erasing files are explained here. After determining the file type (files compressed or encrypted at the file system level are supported on Windows NT and 2000, but Administrator privileges are required for low-level hard disk access), Eraser needs to calculate the size of the file. When calculating the size, the cluster tip area is included so the data stored on it will be erased too. Once the size is calculated, the file will be overwritten with the special method (see detailed descriptions of the methods bellow). Eraser tool takes care of flushing write buffers to make sure that the data really gets written to the hard disk and is not only cashed in a buffer somewhere. If the overwriting was done, the final step is to correctly delete the data. Before erasing the reference of the file from the file table (standard remove), the file will be truncated to 0 length to clear traces of the allocated clusters, the filename will be overwritten and finally file dates (creation, access, modified) will be scrambled to complete the file deleting. Method of Gutmann Based on Peter Gutmann's article "Secure Deletion of Data from Magnetic and Solid-State Memory", the method provides the best security. File will be overwritten 35 times with carefully chosen patterns, which makes it unrecoverable. This method is used as the default for removing data, but has been proven to be very slow when erasing unused space on a hard disk (could be many gigabytes). A Faster Method - US DoD 5220-22.M Two methods based on United States Department of Defense recommendation 5220-22.M from January 1995. The data will be overwritten seven times making this method significantly faster than the Method of Gutmann, but also less secure when it comes to hardware recovery. Pseudorandom Data All passes will be pseudorandom data, which is very incompressible. Therefore, this is the only method that should be used when overwriting unused space or information on a compressed drive. The number of passes is user selectable from one to 65535. Being the fastest method, this one is used as default for overwriting free HDD space.
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Most people have some files that they would rather not share with other people - passwords, private information, self-written poems, the list can be expanded forever. Perhaps you have stored some of this information on your PC where it is easily at your reach, but when the time comes to delete the information from your disk, things get a little bit more difficult and keeping your privacy is not as simple as it may have seemed at a first glance.
Author is founder of Free Security Applications site. Visit this page to learn more about free file erasing solution.
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