Shred Files - Delete Files Securely

Post date: Mar 18, 2010 1:58:17 AM

This procedure allows you to securely delete your files without a trace.

procedure ShredFile(FileName: string);
const
  Buffer       = 1024;
  Counttowrite = 34;
  FillBuffer: array[0..5] of Integer = ($00, $FF, $00, $F0, $0F, $00);
var
  arr: array[1..Buffer] of Byte;
  f: file;
  i, j, n: Integer;
begin
  AssignFile(f, FileName);
  Reset(f, 1);
  n := FileSize(f);
  for j := 0 to Counttowrite do
  begin
    for i := 1 to n div Buffer do
    begin
      BlockWrite(f, FillBuffer[j], Buffer);
    end;
  end;
  CloseFile(f);
  RenameFile(FileName, ExtractFilepath(FileName) + '$000000.tmp');
  DeleteFile(ExtractFilepath(FileName) + '$000000.tmp');
end;

Usage:

procedure ShredAndDeleteFile(const FileName: string);
var
  newname: string;
begin
  newname := ExtractFilepath(FileName) + '$000000.tmp';
  if not RenameFile(FileName, newname) then
    raise
    Exception.CreateFmt('Fehlercode 2: Can %s not Delete!', [FileName]);
  ShredFile(newname);
  DeleteFile(newname);
end;