Hello, I have a multitenant system where we pull in data via sftp for processing, everything works very well, with passwords, but with private_keys, I have a probem.

I see the options:

  * `:user_dir` - The directory to read private keys from.

  * `:private_key_path` - The path to the private key to use for authentication.

  * `:key_cb` - A 2-item tuple containing:
     - A module that implements `:ssh_client_key_api` behaviour.
     - `:ssh_client_key_api` behaviour opts.

might be helpful when using private keys. user_dir is unlikely to be helpful in my case given we don't have user_dir for each user.
I am trying to use: :private_key_path - so I store the private key in a temp file and using this attribute send that with the options, however, I get:

connection_result: {:error,
 %SFTPClient.ConnError{
   message: "Unable to connect using the available authentication methods"
 }}

I have also tried to use: {:key_cb, {AvkService.SSHApi.DatabaseClientKey, private_key: auth_secret}}and then override def user_key(algorithm, opts) do`, but I get the same error.

Finally, I have also played with the modify_algorithms - as mentioned on the home page, but I always get the public key, but always the same error:

{:modify_algorithms, [
  prepend: [
    public_key: [:"ssh-ed25519", :"ecdsa-sha2-nistp256"]  # Try these first
  ],
  append: [
    public_key: [:"ssh-rsa"]  # Try this as a last resort
  ]
]}

Can you give me a some help implementing private keys for multiple users against multiple sftp servers? Thanks,
Bill