Author(s): Mathieu Bozzio, Claude Crépeau, Petros Wallden, and Philip Walther Cryptography not only involves the sending of secret messages but also encompasses many protocols and procedures that provide privacy and security in the networked world. Likewise, quantum resources have the potential to enhance cryptography in ways that go beyond the well-known example of quantum key distribution. This review offers a classification of the main crypto primitives that are available quantum mechanically. It explains the security that they offer, including the sometimes significant limitations on their theoretical capabilities. Implementations using current photonic techniques are discussed. [Rev. Mod. Phys. 97, 045006] Published Fri Dec 19, 2025