DH算法实现加密解密代码

Diffie-Hellman (DH)算法是一种非对称加密算法，用于在两个通信方之间共享密钥，而无需事先共享任何秘密信息。这个过程基于数学原理，特别是大数素数和离散对数问题。以下是一个简单的DH算法实现（Python版本）：

from Crypto.PublicKey import DHPublicKey
from Crypto.Random import get_random_bytes
from Crypto.Cipher import PKCS1_OAEP

# 生成一个安全的大素数p和一个相对应的g值
def generate_keys(p, g):
    generator = g
    prime = p
    # Alice的私钥部分
    alice_private_key = get_random_bytes(20)
    # Alice的公钥部分
    alice_public_key = DHPublicKey(generator=generator, key_material=alice_private_key, p=prime)
    
    # Bob的私钥部分（类似生成）
    bob_private_key = get_random_bytes(20)
    # Bob的公钥部分
    bob_public_key = DHPublicKey(generator=generator, key_material=bob_private_key, p=prime)
    
    return (alice_private_key, alice_public_key), (bob_private_key, bob_public_key)

# 使用Alice的公钥计算共享密钥
def compute_shared_secret(alice_private_key, bob_public_key):
    shared_key = alice_private_key * bob_public_key
    return shared_key

# Alice和Bob相互交换公钥后
alice_keys, bob_keys = generate_keys(2**16 + 1, 5)
alice_shared_secret = compute_shared_secret(alice_keys, bob_keys)
bob_shared_secret = compute_shared_secret(bob_keys[0], alice_keys)

# 对明文进行加密
def encrypt(message, shared_secret, cipher):
    ciphertext = cipher.encrypt(message)
    return ciphertext

# 对密文进行解密
def decrypt(ciphertext, shared_secret, cipher):
    plaintext = cipher.decrypt(ciphertext)
    return plaintext

# 示例：使用共享密钥进行加密和解密
alice_cipher = PKCS1_OAEP.new(alice_shared_secret)
bob_cipher = PKCS1_OAEP.new(bob_shared_secret)

message = "This is a secret message"
encrypted_message = encrypt(message, alice_shared_secret, alice_cipher)
decrypted_message = decrypt(encrypted_message, bob_shared_secret, bob_cipher)

print("Original Message:", message)
print("Encrypted Message:", encrypted_message)
print("Decrypted Message:", decrypted_message)