kvantumkulcselosztás

kvantumkulcselosztás refers to methods of distributing cryptographic keys using the principles of quantum mechanics. Unlike classical key distribution, which relies on the mathematical difficulty of certain problems, quantum key distribution (QKD) leverages the fundamental laws of physics to ensure security. The most well-known QKD protocol is BB84, developed by Charles Bennett and Gilles Brassard in 1984.

In BB84, the sender (Alice) encodes bits of a secret key into the quantum states of photons. For example, she might use different polarizations of light to represent 0s and 1s, employing two different bases for encoding. The receiver (Bob) then measures these photons, also choosing bases randomly. After measuring, Alice and Bob publicly compare which bases they used for each photon. When their bases match, they know they have successfully shared a secure bit of the key.

The security of QKD stems from the no-cloning theorem and the fact that any attempt by an eavesdropper (Eve) to intercept and measure the photons will inevitably disturb their quantum states. This disturbance can be detected by Alice and Bob when they compare a subset of their key bits. If the error rate is too high, they discard the key and try again, knowing that their communication has been compromised. This inherent property of quantum mechanics provides a level of security not achievable with classical cryptography.