Quantum cryptography

Quantum cryptography is the exploiting of quantum-mechanical properties such as quantum entanglement, measurement disturbance, no-cloning theorem, and the principle of superposition to perform encryption tasks. Quantum encryption plays a crucial role in the secure processing, storage, and transmission of information. One aspect of quantum cryptography is quantum key distribution (QKD), which offers an information-theoretically secure solution to the key-exchange problem. Quantum cryptography allows the completion of cryptographic tasks that are proven or conjectured to be impossible using only classical (i.e., non-quantum) communication. Furthermore, quantum cryptography affords the authentication of messages, which allows the legitimate parties to prove that the messages were not wiretapped during transmission. Thus, in a cryptographic set-up, it is impossible to copy, with perfect fidelity, the data encrypted in a quantum state. If one attempts to read the encrypted data, the quantum state will be changed due to wave function collapse (no-cloning theorem). This could be used to detect eavesdropping in QKD schemes, or in quantum communication links and networks. These advantages make quantum cryptography important in the digital age, where devices are increasingly interconnected and cyberattacks have become increasingly sophisticated. Quantum-mechanical properties – more specifically, quantum authentication – are critical components in the advancement of a quantum internet, as they establish robust mechanisms to ensure the long-term privacy and integrity of digital communications and systems.