Often times, there is sensitive data that is stored on your SharePoint machines. This data can be stored at several levels in several formats, the most critical of which to delete when necessary is various backup packages, such as site template packages (.stp's), manifest and dump files (from the SharePoint backup utility), or SQL backups.

Data that is stored, however later deleted, is subject to Data Remanence, which is certain fragments of data still existing, and recoverable by using utilities or skillful shell programming.

Most often, these are simplify deleted using standard deletion techniques, which more often than not will just remove references to files or other deletion methods that still allow data retrieval by an interested party.

Scrubbing the data can leverage a variety of algorithms, the four that are currently supported by the SharePoint Scrubber are:

Currently supported algorithms (along with passing specifications)

B. Schneiers / (typically will scrub with 7 data passes)
Fill Zeros / (typically will scrub data with 1 pass)
NAVSOP5239-26 (typically will scrub with 3 data passes)
Peter Gutmann (typically will scrub with 35 data passes)