Encrypted images for amazon photo

what is the format of the encrypted images?
If a dng(raw) or a jpeg file is encrypted would it still have the same extension and would it be recognized as an image file?
Amazon prime photos offer unlimited storage for image files but only for image files ( jpeg, dng etc.) but I want additional protection that I could control.

I guess IOS --> encrypt --> upload to Amazon photos would be a nice feature and would bring many cloud shy on board.

The complete file is encrypted. Also filename and file type. Amazon will not recognize the file as photos.