I want to know whetehr frePBX is able or has feature to encrypt the call recording files that stor under /var/spool/asterisk/monitor.
You can run a "post recording" command to do almost anything to the recordings. You can move them, transcode them, or email them (or almost anything else) once the recordings are complete.
Do you mind to let me know the command (or just post recording)? Does the command manually run or able to set auto run?
It's not that hard to setup. Google "FreePBX Post Recording Script" Or search in the community, there's bunch of related posts.
If you get stuck, come back here.