Two, Three and Four Dimensional BB84: A Comparative Analysis Based on C# Simulation

Quantum Cryptography, the principles of which are based on the laws of quantum mechanics, is a new approach to secure communication. The main advantages of quantum cryptography as opposed to classical cryptography are: unconditional security, the transmission of an encryption key of a length equal to that of the message, the impossibility of creating an identical copy of an unknown quantum state, and the disruption of the quantum system when trying to measure it. BB84 is the first and best known quantum protocol. It was created in 1984 by Charles Bennett and Gilles Brassard and represents a quantum key distribution. The basic idea of the protocol is to encode bits using photon polarization, one bit for each photon. The paper presents an improvement of the protocol by using quantum memory and coding two, three or four bits for each photon, achieving a great efficiency and a higher security level.