My research involves many aspects of quantum information theory, with a bias towards cryptography, and how it interfaces with quantum foundations. The central motivation is to discover what the laws of physics give us in terms of information processing power. Only relatively recently we have begun to realise some of the power given to us by quantum mechanics and one of the most promising applications is to cryptography, where protocols based on quantum information allow us to do things that are impossible using classical information alone. Which features of quantum theory are responsible for these cryptographic protocols? and what would the world look like if we were to take them away or modify them within a new theory?