量子密码学：量子力学的信息安全

    import random
    
    def generate_bases(n):
    return [random.choice(['rectangular', 'diagonal']) for _ in range(n)]
    
    def encode_bit(bit, base):
    if base == 'rectangular':
        return 'H' if bit == 0 else 'V'
    else:
        return 'D' if bit == 0 else 'A'
    
    def measure_bit(state, base):
    if base == 'rectangular':
        return 0 if state == 'H' else 1
    else:
        return 0 if state == 'D' else 1
    
    def bb84(n):
    # Alice generates random bits and bases
    alice_bits = [random.randint(0, 1) for _ in range(n)]
    alice_bases = generate_bases(n)
    
    # Alice encodes her bits in quantum states
    quantum_states = [encode_bit(bit, base) for bit, base in zip(alice_bits, alice_bases)]
    
    # Bob measures the quantum states using random bases
    bob_bases = generate_bases(n)
    bob_bits = [measure_bit(state, base) for state, base in zip(quantum_states, bob_bases)]
    
    # Alice and Bob compare their bases and keep the bits where the bases match
    key = [bit for bit_a, bit_b, base_a, base_b in zip(alice_bits, bob_bits, alice_bases, bob_bases) if base_a == base_b]
    
    return key
    
    # Example usage
    key = bb84(100)
    print("Key length:", len(key))
    print("Key:", key)
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
    代码解读

    import random
    import numpy as np
    
    def generate_measurements(n):
    return [random.choice([0, 1, 2]) for _ in range(n)]
    
    def measure_entangled_state(state, measurement):
    if measurement == 0:
        return np.dot(state, np.array([1, 0])) > 0.5
    elif measurement == 1:
        return np.dot(state, np.array([1, 1])) > 0.5
    else:
        return np.dot(state, np.array([1, -1])) > 0.5
    
    def e91(n):
    # Alice and Bob generate random measurements
    alice_measurements = generate_measurements(n)
    bob_measurements = generate_measurements(n)
    
    # Alice and Bob measure entangled states
    entangled_states = [np.array([1, 1]) / np.sqrt(2) for _ in range(n)]
    alice_bits = [measure_entangled_state(state, measurement) for state, measurement in zip(entangled_states, alice_measurements)]
    bob_bits = [measure_entangled_state(state, measurement) for state, measurement in zip(entangled_states, bob_measurements)]
    
    # Alice and Bob compare their measurements and keep the bits where the measurements match
    key = [bit for bit_a, bit_b, measurement_a, measurement_b in zip(alice_bits, bob_bits, alice_measurements, bob_measurements) if measurement_a == measurement_b]
    
    return key
    
    # Example usage
    key = e91(100)
    print("Key length:", len(key))
    print("Key:", key)
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
    代码解读