Quantum Key Distribution (BB84)

Features

• Simulates BB84 with random bit and basis generation for Alice and Bob.
• Detects eavesdropping by analyzing error rates in a sampled subset.
• Runs multiple trials to compute average key length and detection rates.

How It Works

1. Alice generates random bits and bases (rectilinear or diagonal).
2. Eve may intercept qubits with a given probability, introducing errors.
3. Bob measures qubits in random bases.
4. Alice and Bob publicly compare bases, keeping bits where bases match.
5. A sample of bits is checked for errors to detect eavesdropping.
6. Remaining bits form the shared key.

Usage

Run a Single Simulation

from qkd_simulator import quantum_key_distribution

n = 8  # Number of qubits
eavesdrop_prob = 0.3  # Eavesdropping probability
key, detected = quantum_key_distribution(n, eavesdrop_prob)
print(f"Shared key: {key}, Eavesdropper detected: {detected}")

Run Multiple Simulation

from qkd_simulator import simulate_qkd

trials = 100
n = 8
eavesdrop_prob = 0.3
simulate_qkd(trials, n, eavesdrop_prob)

Requirements

• Python 3.x
• No external libraries required (uses random and statistics from the standard library)