/// <summary>
/// Radio Button - Delete Algorithm - selects checked
/// </summary>
public void rb_Checked(object sender, RoutedEventArgs e)
{
algorithm = (DeleteAlgorithm.DeleteAlgorithmEnum)((sender as RadioButton).Content);
}
/// <summary>
/// Method to purge a volume
/// Based on the U.S. Department of Defense's standard 'National Industrial Security Program Operating Manual' (DoD 5220.22-M ECE).
/// </summary>
/// <param name="selectedVolume"></param>
public static async Task eraseVolume(CancellationToken ct, Volume selectedVolume, DeleteAlgorithm.DeleteAlgorithmEnum algorithm = DeleteAlgorithm.DeleteAlgorithmEnum.DoD_7)
{
// Variables
var dummyFilesCount = Math.Floor((double)selectedVolume.AvailableFreeSpace / MAX_BUFFER_SIZE);
byte[] pattern = new byte[] { 0x00, 0xFF, 0x72, 0x96, 0x00, 0xFF, 0x72 };
int loops = 6;
if (algorithm == DeleteAlgorithm.DeleteAlgorithmEnum.DoD_3)
{
loops = 2;
pattern = new byte[] { 0x00, 0xFF, 0x72 };
}
ThreadSafeRandom.Shuffle <byte>(pattern);
Random random = ThreadSafeRandom.Random;
// Set progressbar
MainWindow.PGBar.Maximum = selectedVolume.AvailableFreeSpace;
MainWindow.PGBar.Value = 0;
// available free space will be filled with random files
for (int i = 1; i <= dummyFilesCount; i++)
{
// Write asynchronous to implement cancel button
using (FileStream fs = File.Create(selectedVolume.Name + i, MAX_BUFFER_SIZE, FileOptions.Asynchronous))
{
// Loop 3-7 times (DoD 5220.22-M / ECE)
for (int pass = 0; pass <= loops; ++pass)
{
fs.Position = 0;
if (ct.IsCancellationRequested)
{
ct.ThrowIfCancellationRequested();
return;
}
long bufferSize = MAX_BUFFER_SIZE;
byte[] buffer = new byte[bufferSize];
if (pass != 1 && (algorithm == DeleteAlgorithm.DeleteAlgorithmEnum.DoD_7 && pass != 5))
{
for (int bufferIndex = 0; bufferIndex < bufferSize; ++bufferIndex)
{
buffer[bufferIndex] = pattern[pass];
}
}
else
{
for (int bufferIndex = 0; bufferIndex < bufferSize; ++bufferIndex)
{
buffer[bufferIndex] = (byte)(random.Next() % 256);
}
}
// Create file
await fs.WriteAsync(buffer, 0, buffer.Length, ct);
// Delegate event for progressbar
MainWindow.PGBar.Dispatcher.Invoke(EmptyDelegate, DispatcherPriority.Background);
MainWindow.LabelProgress.Dispatcher.Invoke(EmptyDelegate, DispatcherPriority.Background);
fs.Flush(true);
}
// Increase progressbar
MainWindow.LabelProgress.Content = Math.Round(i / dummyFilesCount, 3) * 100 + " %";
MainWindow.PGBar.Value += MAX_BUFFER_SIZE;
}
}
// After everything is done, delete everything again
VolumeController.deleteVolume(selectedVolume);
}
/// <summary>
/// Radio Button - Delete Algorithm Unchecked
/// </summary>
public void rb_Unchecked(object sender, RoutedEventArgs e)
{
algorithm = DeleteAlgorithm.DeleteAlgorithmEnum.DoD_7;
}
