#!/bin/bash

# Disk Wipe (dw) is a simple tool to securely destroy data on a disk by writing 
# random data on it.
#
# Copyright (C) 2005, Ray Soucy <ray.soucy@maine.edu>
# University of Maine, Fort Kent (UMFK)
#
# This program is Free Software as defined by the GNU General Public License 
# version 2 or later.  See COPYING for details.
#
# This tool will prevent forensic software from retrieving data from a disk, 
# but will not offer protection against Magnetic Force Microscopy (MFM) 
# recovery techniques.
#
# This should not be used for military data destruction.  The DoD recommends a 
# minimum of seven wipes with random data.  This script can easilly be 
# modified to do this.

# Usage: dw <device>
# Example: dw /dev/fd0 (wipe a floppy disk)

instructions()
{
    echo
    echo "Disk Wipe (dw)"
    echo "Copyright (C) 2005, Ray Soucy <ray.soucy@maine.edu>"
    echo
    echo "Disk Wipe will write random data to a device to avoid data recovery "
    echo "techniques."
    echo
    echo "Usage: dw <device>"
    echo "Example: dw /dev/fd0 (wipe a floppy disk)."
    echo
    echo "Device reference:"
    echo
    echo "    IDE Primary Master:   /dev/hda"
    echo "    IDE Primary Slave:    /dev/hdb"
    echo "    IDE Secondary Master: /dev/hdc"
    echo "    IDE Secondary Salve:  /dev/hdd"
    echo

    return
}

disk-wipe()
{
    echo "WARNING: All data on $1 will be overwritten."
    echo "Continue? (y/N)"
    read confirm
    if [ $confirm == "y" ] || [ $confirm == "Y" ]
        then
            device=$1
        else
            device="/dev/null"
            exit 0
    fi


    # urandom isn't truely random, but because /dev/random takes a very long 
    # time to come up with truely random data we use /dev/urandom instead.

    dd if=/dev/urandom of=$device bs=512


    # after we write random data to the file we zero it out

    dd if=/dev/zero of=$device bs=512


    return
}


if [ $# == 1 ]
    then
        disk-wipe $1
    else
        instructions
fi