Does anybody know a way of either converting (on android) a putty key to something I can use in ConnectBot, or a good android SSH app that can use Putty keys natively?
I am away from home without my laptop, which I would usually use. I only have my android phone with me.
A few months ago I tried creating RSA key pairs to use with Putty on my laptop and ConnectBot but for some reason I just could not crack it so gave up. I also used puttygen to create an RSA key but it would not work on ConnectBot
Unless you have one of the dumbed down Fido or whatever only versions yubikey is just a smartcard with key storage, and multiple different applications for interfacing with the keys - and as everybody (at least everybody sane) uses the same crypto algorithms those can be shared for whatever needs that.
For SSH you’ll have at least two options - if you have a GPG key on that thing just use the auth-key on there (create one if you don’t have that yet) for SSH, if not maybe adding a PIV key is the better option, that should be available via PKCS#11 then. There might be additional options as well, though.