Explanation of security options

Our app offers 2 ways to overwrite deleted data to prevent it's recovery.

First option, which we call "quick overwrite" will process file allocation table only, and will erase headers of deleted files and folders. Second option - "full overwrite" will write random data to all free disk space.

Quick overwrite: pros and cons.
Main benefit of quick overwrite is that it takes just few minutes. In this mode our app will scan file allocation table for headers of files (and folders) which were deleted. Then, it will create fake files (and folders) in the same places and this will overwrite headers of deleted files. In such case recovery apps wont be able to detect location of deleted files because their headers has been replaced and deleted. But it leaves a chance that using deep disk scan content of deleted files can be recovered, but this requires manual review of gigabytes of data, some knowledge, so we don't believe that it worth it and somebody will do it. But to be sure we have created our second option - full overwrite.

Full overwrite: pros and cons.
In this mode our app will create a very large temporary file with the random data that will take all free space on your hard drive. Thus, it will overwrite all free space making impossible to recover data even with the deep disk scan, including headers in the file allocation table. In this mode you can choose number of passes to write data to the disk, which can prevent caching on some drives. The only one problem with this mode that it could take over 15 minutes to process disk (for some disks it could take hours), and it depends on the size of the disk and it's performance.

Third option is a combination of quick and full overwrite. If you worry a lot about possible recovery - you can run both ways - quick and full overwrite at once.

★ User manual (all help topics)
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★ Why it's important to always process system disk even if you just wipe data on external one
★ Explanation of security options
★ Why quick mode is not available for all disks?
★ Why I don't see some disks in the list for processing?