We are trying to encrypt files in a manner that they can be completely secure in an insecure environment (like a public cloud). We're talking about military grade secure.
The data should be so secure in the public cloud, that the employees cannot access the files (insider threat) and no MitM can access the file.
Our initial idea was to make a VPN (OpenVPN) tunnel between the customer and the public cloud and encrypt the files exchanged using PGP (GnuPG).
Is this secure enough for this use case? We are dealing with PII.
P.S. is it possible to somehow split out trust for the private key on multiple servers on multiple split files on multiple cloud providers?