利用Python Cryptography库实现高级加密功能

cryptography 是 Python 中一个强大且广泛使用的加密库，它提供了多种加密算法和工具来支持加密、解密、签名、验证等操作。以下是如何在 Python 中使用 cryptography 库的一些基本示例。

首先，你需要安装 cryptography 库。你可以使用 pip 来安装它：


pip install cryptography
pip install cryptography
pip install cryptography

对称加密

对称加密是一种使用相同密钥进行加密和解密的加密方法。以下是如何使用 cryptography 库进行对称加密和解密的示例：


from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding
from cryptography.hazmat.backends import default_backend
import os
# 生成一个随机的密钥
key = os.urandom(32)  # AES-256 需要 32 字节的密钥
iv = os.urandom(16)   # 初始化向量 (IV)
# 原始数据
data = b"Secret Message"
# 填充数据以符合块大小要求
padder = padding.PKCS7(algorithms.AES.block_size).padder()
padded_data = padder.update(data) + padder.finalize()
# 创建加密器
cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
encryptor = cipher.encryptor()
# 加密数据
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()
print("Encrypted:", encrypted_data)
# 创建解密器
decipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
decryptor = decipher.decryptor()
# 解密数据
decrypted_padded_data = decryptor.update(encrypted_data) + decryptor.finalize()
# 去除填充
unpadder = padding.PKCS7(algorithms.AES.block_size).unpadder()
decrypted_data = unpadder.update(decrypted_padded_data) + unpadder.finalize()
print("Decrypted:", decrypted_data.decode())
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding
from cryptography.hazmat.backends import default_backend
import os

# 生成一个随机的密钥
key = os.urandom(32)  # AES-256 需要 32 字节的密钥
iv = os.urandom(16)   # 初始化向量 (IV)

# 原始数据
data = b"Secret Message"

# 填充数据以符合块大小要求
padder = padding.PKCS7(algorithms.AES.block_size).padder()
padded_data = padder.update(data) + padder.finalize()

# 创建加密器
cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
encryptor = cipher.encryptor()

# 加密数据
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()

print("Encrypted:", encrypted_data)

# 创建解密器
decipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
decryptor = decipher.decryptor()

# 解密数据
decrypted_padded_data = decryptor.update(encrypted_data) + decryptor.finalize()

# 去除填充
unpadder = padding.PKCS7(algorithms.AES.block_size).unpadder()
decrypted_data = unpadder.update(decrypted_padded_data) + unpadder.finalize()

print("Decrypted:", decrypted_data.decode())
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding
from cryptography.hazmat.backends import default_backend
import os

# 生成一个随机的密钥
key = os.urandom(32)  # AES-256 需要 32 字节的密钥
iv = os.urandom(16)   # 初始化向量 (IV)

# 原始数据
data = b"Secret Message"

# 填充数据以符合块大小要求
padder = padding.PKCS7(algorithms.AES.block_size).padder()
padded_data = padder.update(data) + padder.finalize()

# 创建加密器
cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
encryptor = cipher.encryptor()

# 加密数据
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()

print("Encrypted:", encrypted_data)

# 创建解密器
decipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
decryptor = decipher.decryptor()

# 解密数据
decrypted_padded_data = decryptor.update(encrypted_data) + decryptor.finalize()

# 去除填充
unpadder = padding.PKCS7(algorithms.AES.block_size).unpadder()
decrypted_data = unpadder.update(decrypted_padded_data) + unpadder.finalize()

print("Decrypted:", decrypted_data.decode())

非对称加密

非对称加密使用一对密钥（公钥和私钥）进行加密和解密。以下是如何使用 cryptography 库进行非对称加密和解密的示例：


from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives import serialization
# 生成私钥
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
    backend=default_backend()
)
# 生成公钥
public_key = private_key.public_key()
# 原始数据
data = b"Secret Message"
# 使用公钥加密
ciphertext = public_key.encrypt(
    data,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)
print("Encrypted:", ciphertext)
# 使用私钥解密
plaintext = private_key.decrypt(
    ciphertext,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)
print("Decrypted:", plaintext.decode())
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives import serialization

# 生成私钥
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
    backend=default_backend()
)

# 生成公钥
public_key = private_key.public_key()

# 原始数据
data = b"Secret Message"

# 使用公钥加密
ciphertext = public_key.encrypt(
    data,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

print("Encrypted:", ciphertext)

# 使用私钥解密
plaintext = private_key.decrypt(
    ciphertext,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

print("Decrypted:", plaintext.decode())
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives import serialization

# 生成私钥
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
    backend=default_backend()
)

# 生成公钥
public_key = private_key.public_key()

# 原始数据
data = b"Secret Message"

# 使用公钥加密
ciphertext = public_key.encrypt(
    data,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

print("Encrypted:", ciphertext)

# 使用私钥解密
plaintext = private_key.decrypt(
    ciphertext,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

print("Decrypted:", plaintext.decode())

数字签名

数字签名用于验证数据的完整性和来源。以下是如何使用 cryptography 库进行数字签名和验证的示例：


from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import serialization
# 生成私钥
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
    backend=default_backend()
)
# 生成公钥
public_key = private_key.public_key()
# 原始数据
data = b"Message to sign"
# 创建签名
signature = private_key.sign(
    data,
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)
print("Signature:", signature)
# 验证签名
try:
    public_key.verify(
        signature,
        data,
        padding.PSS(
            mgf=padding.MGF1(hashes.SHA256()),
            salt_length=padding.PSS.MAX_LENGTH
        ),
        hashes.SHA256()
    )
    print("Signature is valid.")
except Exception as e:
    print("Signature is invalid:", e)
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import serialization

# 生成私钥
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
    backend=default_backend()
)

# 生成公钥
public_key = private_key.public_key()

# 原始数据
data = b"Message to sign"

# 创建签名
signature = private_key.sign(
    data,
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)

print("Signature:", signature)

# 验证签名
try:
    public_key.verify(
        signature,
        data,
        padding.PSS(
            mgf=padding.MGF1(hashes.SHA256()),
            salt_length=padding.PSS.MAX_LENGTH
        ),
        hashes.SHA256()
    )
    print("Signature is valid.")
except Exception as e:
    print("Signature is invalid:", e)
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import serialization

# 生成私钥
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
    backend=default_backend()
)

# 生成公钥
public_key = private_key.public_key()

# 原始数据
data = b"Message to sign"

# 创建签名
signature = private_key.sign(
    data,
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)

print("Signature:", signature)

# 验证签名
try:
    public_key.verify(
        signature,
        data,
        padding.PSS(
            mgf=padding.MGF1(hashes.SHA256()),
            salt_length=padding.PSS.MAX_LENGTH
        ),
        hashes.SHA256()
    )
    print("Signature is valid.")
except Exception as e:
    print("Signature is invalid:", e)