So, I've had a bit of a stupid idea for my next programming project, which would be implementing a Microsoft Recall alternative for Linux where the data is encrypted. I've now written a bit of code and have come to the point where I'd need to encrypt the files. My plan was to use asymmetric encryption where the secret key is again encrypted using something like AES and the user needs to decrypt the private key to view the screenshots taken / data extracted from the screenshots.

I have now learned that asymmetric encryption is very slow and it's generally not designed to encrypt large chunks of data, so I'm not sure how to continue. Do you think asymmetric encryption is feasible for this? Any idea how else to do the encryption? Ideally I would like for the server that takes the screenshots to not have a key that can decrypt the files since that wouldn't be as secure.