"Verschlüsselte" Bilddateien "entschlüsseln"

[nicodex]

Nimm mal die ersten vier Bytes ("CF10") weg und XOR die restlichen Bytes mit $8D.

edit:

Delphi-Quellcode:

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