How to permanently delete data from a hard disk

According to a New York Times basic Privacy survey, there are widespread misconceptions about the removal of data from hard disks. The vast majority of people do not know that just deleting files is not enough, because doing so does not really remove data from the computer cleanly. The survey also found that only 33% of second-hand hard drives actually cleaned up the data. Before you want to discard or sell the hard drive, it is best to determine if the hard drive still has any personal data about privacy. This article can help you if you want to completely erase data by formatting or data shredding software.

When you delete files stored on your computer, the data is not actually removed and their information is stored in a directory that the operating system can query. When you delete a file, you actually simply remove the file from the folder and identify the area as a writable new data. Therefore, the original data can be restored before the area is overwritten by the new data. This is how all data restore software works and restores data files that have been deleted based on the directory. The only way to completely erase data is to overwrite it. You can achieve this by formatting the hard drive or by filling the data erasure software with random numbers on your hard disk.

Two main methods of data coverage.

One, the Gutmann method

It is based on the 1996 paper by Professor Peter Gutman at the sixth session of the Usenix security conference at the Oakland University School of Computer Science-"secure deletion of data on magnetic solid storage". This is by far the safest method of data deletion------Overwrite data 35 times, making any attempt to restore data futile. Unfortunately, this method can take quite a long time.

Two, US DoD 5220-22.m

This method is part of the U.S. Department of Defense's "cleaning and disinfection standard", which requires only a few data coverage, security is not Gutman method high, but the time spent is relatively small. Of course, this coverage of several times are fastidious, such as using the complement and random numbers to cover data.

Of course, if someone tells you the maximum number of times you need to overwrite your data, then he must be misleading you. No one knows how many times it will be enough. If you don't want to take any chances at all, you need to make sure that you never write any important content to the disk and decrypt it directly into locked memory. Have no choice.

How to erase data thoroughly under windows

Eraser is a free and open source data removal software. Operating platform, from DOS to Windows 2003, to support the removal of data from a single file, folder and entire hard drive. The software provides three ways to overwrite data, including the two described above, and a "pseudo random data method." This method is used only on unused areas and compressed drives.