Simple 1 Pass:
Quick, but not so secure method. Uses single pass and fills free space with random data.
Schneier 7 Pass:
Based on Bruce Schneier's algorithm. It relies on a cryptographically secure random number generator wo wipe with random data. It overwrites data 7 times. It is very secure and can be used for private files.
DoD 7 Pass:
on U.S. Department of Defense's standard "National Industrial Security Program Operating Manual" (U.S. DoD 5220.22-M ECE). It overwrites data 7 times. This method incorporated the DoD-3 method. It is secure and should be used for general files. It can also be used by many commercial enterprises.
Gutmann 35 Pass:
on Peter Gutmann's algorithm. The data will be overwritten 35 times using patterns. While this method takes the longest amount, it is the most secure method.
Drive Wipe and Erase Software for
Flash, External, and Hard Drives