椭圆曲线加密算法python代码实现

椭圆曲线密码学（Elliptic Curve Cryptography, ECDH 或 ECC）是一种基于数学难题的公钥密码体制，它的安全性来自于椭圆曲线上的点运算。在Python中，我们可以利用像`cryptography`这样的库来实现ECC。

以下是一个简单的Python代码示例，展示如何使用`cryptography`库创建一个ECC密钥对，并进行加密解密：

from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric.utils import (
    encode_dsa_signature,
    decode_dsa_signature,
)

# 创建椭圆曲线实例
curve = ec.SECP256R1()

# 生成随机私钥和公共密钥
private_key = ec.generate_private_key(curve)
public_key = private_key.public_key()

# 将公钥转化为PEM格式便于传输
public_pem = public_key.public_bytes(
    encoding=serialization.Encoding.PEM,
    format=serialization.PublicFormat.SubjectPublicKeyInfo,
)

# 加密消息
def encrypt(message, public_pem):
    shared_secret = private_key.exchange(ec.ECDH(), bytes.fromhex(public_pem))
    encrypted = shared_secret.to_bytes(32, 'big')  # 假设消息长度小于32字节
    return encrypted

# 解密消息
def decrypt(encrypted, private_key_pem):
    private_key = serialization.load_pem_private_key(private_key_pem, password=None)
    shared_secret = private_key.exchange(ec.ECDH(), encrypted)
    decrypted = shared_secret.to_bytes(32, 'big')
    return decrypted.decode('utf-8')

# 示例
message = "Hello, ECDH!"
encrypted_msg = encrypt(message.encode(), public_pem.hex())
print("Encrypted:", encrypted_msg)
decrypted_msg = decrypt(bytes.fromhex(encrypted_msg), private_key_pem.hex())
print("Decrypted:", decrypted_msg)