What exactly is my public key?

Question

I am trying to use SimpleSSHD (Dropbear) on my Android phone, which creates an SSH Server on the phone. I can connect to the phone with Putty, but I need a single-use password which Dropbear creates.

I'm trying to write a Python script to run from my Raspberry Pi to connect to my Android SSH server, but need to get around the single-use password requirement.

I've seen that I can get around that password requirement, with the use of authorized_keys. Where I'm having trouble is what exactly is the public key, and where to put it.

On my RaspberryPi I successfully created a ~/.ssh/id_rsa.pub file which looks like

ssh-rsa AAAABSh[huge long string of things]asdfg pi@raspberrypi

Then on the Pi, I did the following commands:

touch ~/.ssh/authorized_keys
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

But, Dropbear on Android still says no authorized keys, generating single-use password

Do I need to remove the ssh-rsa and pi@raspberrypi from my public key? Is that why Dropbear isn't seeing an "authorized key"?

Answer 1

The authorized_keys needs to be in dropbear, on the android (The accessor, can not authorise them-selves.)

dropbear should have an authorized_keys file, you must append it to that. It will tell dropbear, to allow access to the owner of the private part of this key.

How to

I have never used dropbear. But if you can, then do something like:

mkdir ~/.ssh/authorized_keys.d #in dropbear

scp ~/.ssh/id_rsa.pub «my_username@my_android»:~/.ssh/authorized_keys.d/id_rsa.pub # in the Pi

cd ~/.ssh; cat authorized_keys.d/*.pub > authorized_keys #in dropbear

Format of the file

Do I need to remove the ssh-rsa and pi@raspberrypi from my public key? Is that why Dropbear isn't seeing an "authorized key"?

NO, do not remove the ssh-rsa, as this will break the file. Do not remove the pi@raspberrypi this is in the comment section, and will be ignored. It is useful when you come to remove keys, as you can see where they came from.

Answer 2

no need to remove You just need to put authorized_keys file in your android /etc/dropbear folder (or in another file /opt/etc/dropbear if there is no /etc/dropbear ).

after that do.

chmod 0600 /etc/dropbear/authorized_keys