Quantum Key Distribution Simulator

Alice sends single photons encoded in random bases (rectilinear + or diagonal x) with random bit values.

Bob independently chooses a random basis for each photon and records the measurement result.

Alice and Bob publicly compare their basis choices (not bit values). They keep only bits where bases matched (~50%).

A random subset of sifted bits is compared to estimate the Quantum Bit Error Rate (QBER). High QBER indicates eavesdropping.

Hash functions compress the key to remove any information an eavesdropper may have gained, producing the final secure key.