I've been sending and getting files using Linux sftp to various providers for many years. The scripts to do this are batch/unattended and utilize a public key for authentication.
A few days ago, this mechanism stopped working with one of the information providers. They said I needed to install a certificate on my end. I've never installed a certificate for this process for either this provider or any other. I'm puzzled as to where I should install this certificate and how sftp is to reference it. I see not command line parameters for specifying a certificate. I'm thinking the provider is mistaken that I need such a thing, but I want to confirm one way or another before I say anything.