Quantum Key Distribution is one of the possible solutions to the problem presented to cryptography by the rise of quantum computers. It offers a fundamentally different way of providing cryptographic security: Instead of relying on computational complexity, the security is provided for by the principles of quantum mechanics. In order for this technique to be used safely, the necessity for rigorous mathematical security proofs that bound the amount of information an eavesdropper can obtain is imminent not only for security, but also for practical use: any such device used in critical infrastructures must first be certified by a national governing body. A preliminary systematic overview of security proof methods for QKD and a discussion of possible implementations of QKD in local critical infrastructures are presented in this paper.