What are SSH Keys?

• A public key file that gets installed into the account you want to log into. This is not sensitive, and can be freely shared with others.
• A private key file that stays secure in your account or on your computer. This is sensitive, and must not be shared with anyone.
• A passphrase, which is a password for the private key. This is also sensitive, and like any password, must not be shared.

SSH keys at CSE

Generating a key

• Connect to a login server or VLAB using your zID and zPass
• From the terminal, run ssh-keygen -t rsa
• Accept the default path and filename when prompted, and be sure to set a secure passphrase
• This will create ~/.ssh/id\_rsa.pub (your public key) and ~/.ssh/id\_rsa (your private key).
• Keep the private key for yourself. Only give the public key to other people.

The default key type that ssh-keygen creates is RSA. It is considered safer now to use elliptic curve key types. eg: ssh-keygen -t ed25519

Adding an SSH key to an account you control.

• Get a copy of the public key.
• Login to the CSE account that want to accept logins using that key.
• Append the public key to the file .ssh/authorized\_keys
  You can do that with an editor or with a shell command like: cat _key.pub_ >> ~/.ssh/authorized_keys
• Ensure the authorized\_keys file is only readable by its account: chmod 600 ~/.ssh/authorized_keys

Adding an SSH key to another account

Using your SSH key from your own computer

Downloading your key

• Set up Cyberduck on your computer, and connect to your own homedir

• Ensure that Edit -> Preferences | Browser | Show Hidden Files is selected.

• Download your private key from .ssh/id\_rsa to your own computer

• If you haven't already, download and install PuTTY on your computer.

• Run the PuTTYgen app that comes bundled with PuTTY

• Go to Conversions -> Import to open the id\_rsa key you downloaded

• Click Save Private Key to save out a .ppk version of the file

Using your key with SSH applications