Transfer sensitive data from Ubuntu to iPhone I'm new to the Apple ecosystem and I'm using Ubuntu as my primary OS on desktop. I have my computer set up as ssh server, and I have generated a public/private keypair on it which I want to transfer to my iPhone. I have just picked a top App Store hit for the ssh client (Termius), but I cannot import my key into it, except by iTunes. 

For obvious reasons, I don't want my private key touching the Internet (and besides, there's no iTunes for Linux), let alone upload it on any cloud service, and would rather copy the keys through my USB cable. However, copying it to the app's data using AFC went unnoticed, and I have no idea if putting it anywhere on the filesystem would do any good (mounting using idevicepair and ifuse). Is there an app or a technique that supports what I'm trying to do?
I’ve been extremely happy with Prompt 2 for ssh clients. It can generate keys and then I set up an isolated network interface and allow ssh in via password while both devices are isolated / secured.

You can then set up the keys as needed over ssh and then disable password if you wish on your ssh server or change back to a network where you disallow password to sign in.

On Apple to Apple you can use all sorts of other ways, too - AirDrop / iMessage / iCloud files or rely on ssh as above. Ubuntu does restrict your other methods. Also, typing out a 2048 length RSA key isn’t too horrible if you absolutely won’t compromise on user/password for temporary ssh setup to exchange keys.


https://library.panic.com/prompt/prompt-key-security/