Kvantumtitkosítás

Kvantumtitkosítás, or quantum cryptography, is a field that utilizes the principles of quantum mechanics to perform cryptographic tasks. Unlike classical cryptography which relies on the computational difficulty of mathematical problems, quantum cryptography leverages quantum phenomena such as superposition and entanglement to achieve security. The most well-known application of quantum cryptography is quantum key distribution (QKD).

QKD protocols allow two parties to generate and share a random secret key with a level of security guaranteed by the laws of physics. The most prominent QKD protocol is BB84, developed by Charles Bennett and Gilles Brassard in 1984. In BB84, a sender (Alice) transmits a stream of photons, each prepared in a specific quantum state representing a bit of information. The receiver (Bob) measures these photons using randomly chosen measurement bases.

The security of QKD stems from the fact that any attempt by an eavesdropper (Eve) to intercept or measure the photons will inevitably disturb their quantum states. This disturbance can be detected by Alice and Bob by comparing a subset of their measurement results. If an eavesdropper is detected, the key is discarded. If no eavesdropping is detected, the remaining bits are used to form a secure cryptographic key.

While QKD focuses on secure key distribution, other areas of quantum cryptography are being explored, including quantum digital signatures and secure multi-party computation. The development of quantum computers poses a significant threat to current public-key cryptography systems, making quantum-resistant cryptographic solutions, including those based on quantum principles, increasingly important for future security.