Secure Erase

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You must use the General Tab under the Configure Tab to specify the type of Secure Erase to be used for the 'Secure Erase' option.  This applies to both PurgeIE Pro and PurgeFox.

You can choose either 'Quick Shred' or 'Thorough Shred'.

The 'Quick Shred' option should be adequate for preventing an 'undelete' utility program from recovering the data files. This simply writes binary zeroes over the complete data file one time.

The 'Thorough Shred' option uses random data in a multiple pass process to overwrite the data file as described in the federal standard "DOD 5220.22-M"

For each of the specified number of passes, the file is overwritten with random data as follows:

pass 1, 4, 7, etc. create a set of random data and write it over the complete data file

pass 2, 5, 8, etc. create a complement of the random data from the previous pass and write it over the complete file

pass 3, 6, 9, etc. create a new set of random data and write it over the complete data file

A complement means that the binary bytes are inverted. Each '1' bit becomes a '0' bit and each '0' bit becomes a '1' bit.

You can find the above Military Spec at -

You can achieve the "DOD 5220.22-M" requirement by specifying 3 passes. As some privacy advocates feel this is not adequate, you can specify up to 99 passes.

Many feel that seven (7) passes with random data should be adequate for hard disks and should prevent forensic tools from recovering the data files.

Note - this can significantly extend the execution time. The greater the number of passes, the longer the execution time.

Note - In both the 'Quick Shred' and 'Thorough Shred' options, the writes include the unused space at the end of the last cluster of disk space used to contain the data file and obliterates the file name in the hard drive directory.

You need to be aware that the Secure Erase process only functions for the files that PurgeIE Pro deletes. For example, if Internet Explorer deletes any Cache files, PurgeIE Pro would not process those files. Such files can be undeleted by special utility programs until such time as their space is used to allocate another data file..

You can minimize deletion of Cache files by Internet Explorer deletes by making sure that you allow it sufficient space for its Cache.

You control this setting by:

1. Start Internet Explorer
2. Click Tools
3. Select Internet Options from the dropdown menu
4. On the General tab of the 'Internet Options' window, click Settings
5. On the Settings window, you can adjust the 'Amount of disk space to use' field.

NOTE You can use PurgeIE's 'Statistics' display to determine how much Cache you currently have allocated. Add together the 'Allocated' values for both 'Online Cache' and 'Offline Cache' from the 'Statistics' display.

Utility programs are available for clearing the unallocated space from your hard drive. These programs would also clean deleted data files as they are, technically, unallocated.

One such "free" secure erase program is "Shred 2" from PC Magazine at

There are also some Shareware programs available.

The above explanations were extracted from the PurgeIE Pro Help file.

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Revised: January 20, 2022