I had some users complaining about my app crashing when working with GTAV RPF archives that were modified by OpenIV. When I investigated the issue, I noticed that OpenIV is changing the encryption flags in the main RPF archive header (i.e bytes # 12 - 15).
As an example, update.rpf in my game files has these bytes 12-15 set to 0x0FEFFFFF (ie. NG encryption) when it's unmodified. But if I edit a file in the archive (eg. make a change to dlclist.xml in the OpenIV editor), afterwards these bytes are set to 0x4E45504F (ie "OPEN").
I've added a workaround to my app to handle this case, but I'm still wondering if there's any reason that OpenIV does this? Or are you just using these bytes to indicate it's been edited by OpenIV?