wipe by Tom Vier <thomassr@erols.com>

wipe is a secure file wiping utility. however, it does not set the
media access bit on scsi commands, therefore it is not 100% secure,
unless your drive has no write cache. for maximum security, disable
drive write cache on scsi mode page 8. if possible, disable operating
system file cache and driver-level buffers. wipe tries to sync the
data to disk via a call to fdatasync(), fsync(), or using O_SYNC. wipe
should make it extremely difficult for all but the most determined
person(s) to recover the original plaintext data. utilities such as
PGP and the GNU Privacy Guard provide strong encryption, but
encryption is useless if the original plaintext can be recovered.

wipe uses /dev/urandom, or if unavailable, /dev/random, as a source
for entropy. the tiger hash is used for speed. more information on the
tiger hash algorithm is at:

http://www.cs.technion.ac.il/~biham/Reports/Tiger/

for more information on the secure deletion of magnetic media and
solid state storage devices (such as DRAM) see the USENIX article by
Peter Gutmann at:

http://www.cs.auckland.ac.nz/~pgut001/secure_del.html
or
http://www.erols.com/thomassr/zero/download/wipe/secure_del.html

Exit codes:

0	--	all files successfully wiped and deleted
>= 1	--	one or more files not successfully wiped
!= 0	--	if it's not zero, then it's probably an errno code
