使用python解决数字签名的完整代码

Python中有多种库可以处理数字签名，比如`cryptography`库，它是一个用于加密、解密、哈希等操作的强大工具。下面是一个简单的示例，展示如何使用`cryptography`库实现消息摘要（HMAC）和RSA数字签名：

from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC

# 定义一个函数来生成私钥和公钥
def generate_keys(password):
    kdf = PBKDF2HMAC(
        algorithm=hashes.SHA256(),
        length=32,
        salt=b'salt',
        iterations=100000,
        backend=default_backend()
    )
    key = kdf.derive(password.encode())
    
    private_key = serialization.load_der_private_key(
        b'-----BEGIN PRIVATE KEY-----\n' + key + b'\n-----END PRIVATE KEY-----\n',
        password=password.encode(),
        backend=default_backend()
    )
    
    public_key = private_key.public_key()
    return private_key, public_key

# 生成一对密钥对
password = b'secret_password'
private_key, public_key = generate_keys(password)

# 消息内容
message = 'Hello, this is an example message.'

# 对消息计算HMAC签名
hmac_signature = private_key.sign(
    message.encode(), # 编码为字节串
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)

# 对消息进行RSA签名
rsa_signature = private_key.sign(
    message.encode(), # 同样编码为字节串
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)

# 显示签名结果
print(f"HMAC Signature: {hmac_signature.hex()}")
print(f"RSA Signature: {rsa_signature.hex()}")

# 验证签名
is_valid_hmac = private_key.verify(
    hmac_signature,
    message.encode(),
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)
is_valid_rsa = public_key.verify(
    rsa_signature,
    message.encode(),
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)

if is_valid_hmac and is_valid_rsa:
    print("Signature validation successful.")
else:
    print("Signature validation failed.")