In various examples there is a computing device in communication with at least one other computing device via a communications network. The computing device has a memory and a central processing unit having a trusted execution environment comprising trusted regions of the memory. The computing device has an operating system configured to create a memory mapping between a virtual address space of the memory and a memory of the at least one other computing device and to provide details of the memory mapping to the trusted execution environment. The trusted execution environment is configured to execute an application which is able to communicate with the other computing device directly using the memory mapping provided by the operating system.