  Quantum cryptography is arguably the fastest growing area in quantum
information science. Novel theoretical protocols are designed on a regular
basis, security proofs are constantly improving, and experiments are gradually
moving from proof-of-principle lab demonstrations to in-field implementations
and technological prototypes. In this review, we provide both a general
introduction and a state of the art description of the recent advances in the
field, both theoretically and experimentally. We start by reviewing protocols
of quantum key distribution based on discrete variable systems. Next we
consider aspects of device independence, satellite challenges, and high rate
protocols based on continuous variable systems. We will then discuss the
ultimate limits of point-to-point private communications and how quantum
repeaters and networks may overcome these restrictions. Finally, we will
discuss some aspects of quantum cryptography beyond standard quantum key
distribution, including quantum data locking and quantum digital signatures.
