Shred Files: Gutmann, Pseudorandom, US DoD 5220-22-M etc.

Hi,

 

I looked in the program help files, in Norton's forum, and online. I got some information online but not from Norton.

 

My questions are about the standards for shredding files in Norton Utilities v15.0 From what I can tell there are 4 different standards with an option to "Clean alternate data streams". I get the basic principal of writing ones and zeros to the drive to remove patterns left behind from data. But what is the difference between:

 

Pseudorandom

US DoD 5220-22-M (8.306 / E)

US DoD 5220-22-M (8.306 / E, C and E) I don't know why it has E twice but you don't have to explain that part.

Gutmann

 

Also what is the "Clean alternate data streams" option?

 

Finally I know flash (thumb drives specifically) work differently and don't last as long as traditional hard drives. I don't plan on wiping my flash drives often but will it drastically shorten the life span?

 

Thanks