How do I connect my agent to the test harness with an encrypted connection?

For folks using an Agent Developer Kit, most of the complexities are handled there. 

Start by checking your ADK supplier’s documentation about the environment needed to meet the data security requirements of the SIF specification. Then apply this guidance http://compliance.sifinfo.org/sifcompliance/docs/HTTPS.jsp.  Otherwise, you are going to have to learn something about the relevant technologies and add these features yourself. However, we do provide a special testing environment for troubleshooting related issues http://compliance.sifinfo.org/sslhello/.