A computing apparatus comprises a plurality of hardware modules (102,104,106) and a shared communication infrastructure (110) by which the modules can communicate with each other in the usual way. In order to increase the level of trust and security in the apparatus, a trusted hardware module (120) is also provided and is connected to the other modules by respective communication paths (122a;122b;122c), distinct from the communication infrastructure, by which each of those modules can communicate directly with the trusted module but cannot communicate directly with any other of the modules. The trusted module can therefore have secure communications, for example of "unsafe" data, with each of the other modules without any of the remaining modules eavesdropping, and the trusted module can route unsafe data between any pair of the other modules, or decline to provide such routing, for example in dependence on policy stored in the trusted module.