How to ensure secure communication between vcloud organization and public internet ?

I have created One Organization  namely “AmbarCloud” in vCloud director 5.1. 

Consider Organization URL is : https://xyzcorp.asia-cloud.com/cloud/org/AmbarCloud/  

Requirement:  Provide access to  Third party users   ( Org Amin access )  so they can access the Organization over internet can do their work. I am going to create Local User  for Org which are having  Role of Org Admin access and provide the same credentials to the Third party users.

My Important requirement is that , I want to ensure that  traffic between “VCloud Organization-  AmbarCloud” &  Destination is Public Internet must be secured and encrypted

Source         : https://xyzcorp.asia-cloud.com/cloud/org/AmbarCloud/  

Destination  :      Third Party user those who are going to login via Remote network from Public internet

How can I  fulfilled above requirement    ?