Hi Xeeynamo,
I saw this thread and created an account just to ask you a question.
How did you find these JSON files? I've been looking for the JSON file for [US] FINAL FANTASY XV PLATINUM DEMO, and haven't been able to find it anywhere. I found that you discovered the JSON file for [EU] FINAL FANTASY XV PLATINUM DEMO, and when I search for the contents of the URL you posted in a search engine, this thread is the only mention of that JSON file anywhere. Any chance you can find the JSON of the [US] FINAL FANTASY XV PLATINUM DEMO for me?
I've been searching for this demo to download for a while. Played this demo on a friend's PS4, and am thinking about buying a PS4 soon, but can't decide which PS4 to purchase since this demo is a deciding factor of which to buy (whether to buy a PS4 with older firmware for a manual install, or a newer PS4 if the demo is available in another country on the PlayStation Store. Also tried looking into buying a PlayStation account that had it previously downloaded, but can't find one that has it for sale).
The only PlayStation Store that seems to have the Platinum Demo still listed is Singapore. See this URL:
Spoiler
I thought that maybe I could create a PlayStation Singapore account to purchase, however downloading from the store isn't an option despite it being listed. Attempted to use the BURP suite to trick a download of the demo of Gravity Rush 2 to instead download the Platinum Demo using this JSON file in the PUT statement:
Spoiler
Unfortunately, I would receive purchase errors when attempting to do that. If you could help find the JSON file for [US] FINAL FANTASY XV PLATINUM DEMO, that would be a huge help! Sorry that I'm unable to answer your question for how to decrypt/unpack the PKG contents for demo preservation.