Software Defined Networks (SDNs) decouple the control plane and the data plane, congregating control functions in a designated entity in the network, the controller. The decoupling realizes a highly dynamic network which has benefits such as cost reductions and programmability. The OpenFlow protocol defines the communication between the controller and the network nodes. This thesis aims to construct a key management scheme for data plane encryption in SDN through an OpenFlow channel secured by TLS. Manual operations are usually embedded in key management solutions, but due to the dynamic nature of SDN, manual operations are not realizable in this architecture. Therefore, an automatic scheme needs to be designed. Consequently, this thesis proposes a scheme for key management where the controller manages and initializes encrypted connections in the data plane. Encryption between the nodes is enabled by the newly developed secure tunneling protocol, WireGuard. The key management procedures are carried out through the secure OpenFlow channel. OpenFlow does not provide functionality for key management operations, and therefore this thesis proposes an extension to the protocol which facilitates this.