Modern quantum technologies of cryptographic information protection

Quantum cryptography is a new paradigm of cryptographic information protection, utilizing the laws of quantum mechanics and the corresponding quantum properties of information carriers — photons to overcome the limitations of classical cryptographic protocols and increase the security of cryptographic protocols up to the information-theoretic level. The paper provides a general overview and analysis of modern quantum information security technologies, particularly protocols for quantum key distribution, quantum secure direct communication, and quantum secret sharing. Several other areas of quantum cryptography are briefly considered, such as quantum digital signature, quantum bit commitment, quantum steganography, etc. The advantages and disadvantages of quantum cryptographic protocols, as well as the prospects and challenges of their practical implementation, are analyzed. A brief overview of the laws of quantum physics underlying the security of quantum cryptographic protocols is also provided. Keywords: quantum cryptography, physical foundations of quantum cryptography, qubit, qudit, entangled qubits and qudits, quantum key distribution, quantum secure direct communication, quantum secret sharing.