A Software-Defined Networking (SDN)-based “upstream” approach is a controller-based solution that provides secure key distribution and management for multi-site data centers. The approach uses an SDN Multi-Site Controller (MSC) that acts as an intermediary between SDN controllers at sites in a multi-site data center and manages the distribution of keys to sites. The approach is not dependent upon any particular routing protocol, such as the Border Gateway Protocol (BGP), and is well suited for multicast stream encryption by allowing the same key to be used for all replicated packets sent to downstream sites from an upstream source site. The approach distributes keys in a secure manner, ensures that data transferred between sites is done in a secure manner, and supports re-keying with error handling.