Please recommend a method to do the following:
Securely transmit some text (a phrase) or a photo from smartphone to Windows computer.
Do the reverse: Securely transmit some text or an image from Windows computer to smartphone.
I want to do this without physically connecting the devices. Ideally using something like OpenPGP.
What I do currently (for non-sensitive data):
I have a To-Do app on my phone and it has a web version. I go to the website (from computer) and create a new todo item, with the text I want to access on my phone. I can also attach a photo. Then I can access it on my phone. I can do the reverse: create a Todo item on the phone (or attach a photo), and I can access it from the computer through the website.
Now I want to be able to do something similar but in a secure/encrypted way.