git push origin master, enter passphrase for key id_rsa

Generate SSH keys:

ssh-keygen

Do not enter passphrase:

Generating public/private rsa key pair.
Enter file in which to save the key (/home/pi/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/pi/.ssh/id_rsa.
Your public key has been saved in /home/pi/.ssh/id_rsa.pub.
The key fingerprint is:

The key's randomart image is:
+---[RSA 2048]----+
|   o+*Bo*+.  +.. |
|. . .*.o.o  . =  |
|.. +o.=..  . . B |
|. o... .. . . + =|
| .      S.   . ..|
|.      + o . . . |
|o       B o . .  |
|.E     . + .     |
|o       . .      |
+----[SHA256]-----+

Do not choos different filename the 'id_rsa'

Output SSH key:

cat /home/pi/.ssh/id_rsa.pub

Open https://github.com/settings/keys and create a new ssh key:

Download and use existing project:

git clone ssh://git@github.com/catonrug/rpi-stretch.git

Create new project

curl -u 'catonrug' https://api.github.com/user/repos -d '{"name":"rpi-stretch","description":"auto configuration"}'
git remote add origin git@github.com:catonrug/rpi-stretch.git