I don't quite understant what the dummy data does.  Is it supposed to make it the same size in kb? or is it something about the offset?  Anyway it seemed to work without the dummy data section.  I don't understand hex either, so I also don't know how to say add X number of dummy data.  Also, in your guide you made the error of saying rename key.bin to current-key.bin when it needs to be common-key.bin.