Execute
photorec on the memory dump:
$ photorec for400/memory.dmp
Scan for Intel/Whole Disk/Other
During the recovery, notice some gpg files recovered:
$ find . -name "*.gpg"
./recup_dir.5/f1459128.gpg
$ file ./recup_dir.5/f1459128.gpg
./recup_dir.5/f1459128.gpg: PGP key security ring
This seems very good!