python文件加密与解密的方法是什么

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Python 文件加密与解密的方法可以使用以下几种方式：

对称加密：使用相同的密钥进行加密和解密。常见的对称加密算法有 AES、DES 等。可以使用 cryptography 库来实现对称加密，具体方法如下：

from cryptography.fernet import Fernet

# 生成密钥
key = Fernet.generate_key()

# 创建加密器
cipher = Fernet(key)

# 加密文件
with open('plain.txt', 'rb') as file:
    plaintext = file.read()
encrypted_text = cipher.encrypt(plaintext)

# 将加密文件写入新文件
with open('encrypted.txt', 'wb') as file:
    file.write(encrypted_text)

# 解密文件
with open('encrypted.txt', 'rb') as file:
    encrypted_text = file.read()
decrypted_text = cipher.decrypt(encrypted_text)

# 将解密文件写入新文件
with open('decrypted.txt', 'wb') as file:
    file.write(decrypted_text)

非对称加密：使用公钥进行加密，私钥进行解密。常见的非对称加密算法有 RSA 等。可以使用 cryptography 库来实现非对称加密，具体方法如下：

from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.backends import default_backend

# 生成 RSA 密钥对
private_key = rsa.generate_private_key(public_exponent=65537,
    key_size=2048,
    backend=default_backend())
public_key = private_key.public_key()

# 保存私钥到文件
with open('private_key.pem', 'wb') as file:
    file.write(
        private_key.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.PKCS8,
            encryption_algorithm=serialization.NoEncryption())
    )

# 保存公钥到文件
with open('public_key.pem', 'wb') as file:
    file.write(
        public_key.public_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PublicFormat.SubjectPublicKeyInfo
        )
    )

# 加密文件
with open('plain.txt', 'rb') as file:
    plaintext = file.read()
encrypted_text = public_key.encrypt(
    plaintext,
    padding.OAEP(mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

# 将加密文件写入新文件
with open('encrypted.txt', 'wb') as file:
    file.write(encrypted_text)

# 解密文件
with open('encrypted.txt', 'rb') as file:
    encrypted_text = file.read()
decrypted_text = private_key.decrypt(
    encrypted_text,
    padding.OAEP(mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

# 将解密文件写入新文件
with open('decrypted.txt', 'wb') as file:
    file.write(decrypted_text)

文件压缩加密：先对文件进行压缩，然后再进行加密。可以使用 zipfile 库进行文件压缩，再结合对称或非对称加密方法进行加密。具体方法如下：

import zipfile
import shutil
from cryptography.fernet import Fernet

# 压缩文件
shutil.make_archive('archive', 'zip', '.', 'plain.txt')

# 加密压缩文件
with open('archive.zip', 'rb') as file:
    plaintext = file.read()
    
# 使用对称加密
key = Fernet.generate_key()
cipher = Fernet(key)
encrypted_text = cipher.encrypt(plaintext)

# 将加密文件写入新文件
with open('encrypted.zip', 'wb') as file:
    file.write(encrypted_text)

# 解密文件
with open('encrypted.zip', 'rb') as file:
    encrypted_text = file.read()

# 使用对称解密
decrypted_text = cipher.decrypt(encrypted_text)

# 将解密文件写入新文件
with open('decrypted.zip', 'wb') as file:
    file.write(decrypted_text)

# 解压缩文件
with zipfile.ZipFile('decrypted.zip', 'r') as zip_ref:
    zip_ref.extractall('.')