When using a private repository for cookbooks, an SSH key must be provided to authenticate to the repository. Depending on the type of key you are using, you may see the following message when performing a refresh action:
credential given is not a valid SSH private key
If you see this message, it indicates that you are not using a valid PEM-formatted RSA/DSA key. As noted in the docs, only PEM-formatted keys are supported. If you are using a newer version of openssh/ssh-keygen, you will need to specify PEM formatting using the `-m PEM` flag on the command-line, such as:
ssh-keygen -m PEM -t rsa -b 4096 -C "your_email@example.com"
