Thanks. And thanks for utility... I cannot find a way to look only for json files.. There is no json format in File Opt. But json mentioned as supported.
There is explanation How to Add your own extension to PhotoRec in wiki.. But franly i do not understand yet.. Do you have experience?
you will have to search for "ASCII" files .. that's why you will probably end up with a whole lot of them in the end ..
// edit: photorec searched every block on the hard drive and tries to figure out if it knows the file format .. *.doc files look different from *.pdf files on the hard drive .. but you can identify them ... ASCII files are plain text .. and used ALOT everywhere on your computer ...
once you have all text files on the computer you may try to search for "master_key_record_type" in all of them .. maybe use some tool to search in all files