"Verschlüsselte" Bilddateien "entschlüsseln"

[nicodex]

Delphi-Quellcode:

const
  FileName = 'D:\Temp\karten.decoded.png';
var
  Source: TFileStream;
  Header: array [0..3] of AnsiChar;
  Stream: TMemoryStream;
  Buffer: PByte;
  Index: Integer;
begin
  Source := TFileStream.Create(FileName, fmOpenRead);
  try
    Stream := TMemoryStream.Create();
    try
      Header := 'CF10';
      Stream.WriteBuffer(Header, SizeOf(Header));
      if Source.Size > 0 then
      begin
        Source.Position := 0;
        Stream.CopyFrom(Source, Source.Size);
        Buffer := Stream.Memory;
        Inc(Buffer, SizeOf(Header));
        for Index := 1 to Stream.Size - SizeOf(Header) do
        begin
          Buffer^ := Buffer^ xor $8D;
          Inc(Buffer);
        end;
      end;
      Stream.SaveToFile(ExtractFilePath(FileName) + ChangeFileExt(
        StringReplace(ExtractFileName(FileName), '.decoded', '',
        [rfReplaceAll, rfIgnoreCase]), '.encoded') + ExtractFileExt(FileName));
    finally
      Stream.Free();
    end;
  finally
    Source.Free();
  end;
end;