procedure CryptBMP(BMP: TBitmap; PW: string); 
var 
  x, z, erg, w, h: integer; 
  p: pByteArray; 
  s: string; 
begin 
  s := ''; 
  erg := 7; 
  for z := 2 to 9 do begin 
    for x := 1 to length(PW) do 
      erg := (erg * 2 + ord(PW[x]) * z) mod 73; 
    s := s + inttostr(erg mod 10) 
  end; 
  randseed := strtoint(s); 
  BMP.pixelformat := pf24bit; 
  for h := 0 to BMP.height - 1 do begin 
    P := BMP.ScanLine[h]; 
    for w := 0 to BMP.width * 3 - 1 do 
      P[w] := P[w] xor Random(256); 
  end; 
end; 
 
// erster Aufruf verschlüsseln, zweiter Aufruf entschlüsseln 
 
procedure TForm1.Button1Click(Sender: TObject); 
begin 
  CryptBMP(Image1.Picture.Bitmap, 'Passwort'); 
  Image1.Refresh; 
end;