We describe the design and implementation of public key infrastructure for the Bristol University Cyberjacket and three initial applications. The first one removes the need for the user to remember passwords, the second application provides an authentic record that a meeting took place; the third provides an authentic record of a conversation. The wearable public key infrastructure (WPKI) we develop uses very small communication, whilst also providing a balanced and low computational overhead on both the “client” and “server” sides.