allow key access for user in ssh

Allow shared key access only for one user in SSH.

Disable the password authentication for one user in your SSH config. Edit /etc/ssh/sshd_config.

Match User username
  PasswordAuthentication no

Restart the SSH service.

service ssh restart

Copy user’s public key to the destination server’s authorized file in ~/.ssh/authorized_keys.

ssh-rsa AAAAxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 

Back on your client, login via SSH. User will not be prompted for password since public key is already authorized on server.

ssh username@server