For private/public key user authentication, Token2Shell and Token2Shell/Mobile look for private/public key files in "ssh\keys" folder under its home folder. For example, if you have set the home folder for Token2Shell as "C:\My Documents", Token2Shell searches private/public keys under "C:\My Documents\Token2Shell\ssh\keys".
Private/Public Key File Format
Token2Shell and Token2Shell/Mobile support private/public key file formats used in OpenSSH (http://www.openssh.org) and SSH Corp.(http://www.ssh.com). Make sure your private/public keys are generated using the application that came with your server.
Private/Public Key File Names
In order for Token2Shell or Token2Shell/Mobile to recognize a key file, a public key file name must be set according to its corresponding private key file name; you must append ".pub" to a private key file name for its corresponding public key file. For example, if your private key file is named "my-server-key", its public key file must be named "my-server-key.pub". Make sure *both* of your private and public key files are in the same "ssh\keys" folder.
When key files are recognized by Token2Shell or Token2Shell/Mobile, they will be listed for SSH options, i.e., [ Encryption(Priv/Pub) Key File ] » "For 'publickey' method", "For 'hostbased' method".
Please note that in order for the "publickey" or "hostbased" user authentication to work, you must also install your public key on your server. (Installing a public key varies from SSH server to server, hence please check your SSH server manual or contact your system administrator for more details. It could be as simple as copying a public key file to a specific folder on your server.)