python rsa 例子

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

def generate_keys():
    # 生成RSA私钥
    private_key = rsa.generate_private_key(
        public_exponent=65537,
        key_size=2048,
        backend=default_backend()
    )

    # 提取公钥
    public_key = private_key.public_key()

    # 将私钥保存到文件
    with open("private_key.pem", "wb") as f:
        f.write(private_key.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.TraditionalOpenSSL,
            encryption_algorithm=serialization.NoEncryption()  # 如果需要可以添加密码保护
        ))

    # 将公钥保存到文件
    with open("public_key.pem", "wb") as f:
        f.write(public_key.public_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PublicFormat.SubjectPublicKeyInfo
        ))

def load_private_key():
    # 从文件加载私钥
    with open("private_key.pem", "rb") as key_file:
        private_key = serialization.load_pem_private_key(
            key_file.read(),
            password=None,  # 如果之前设置了密码，则需要在这里提供
            backend=default_backend()
        )
    return private_key

def load_public_key():
    # 从文件加载公钥
    with open("public_key.pem", "rb") as key_file:
        public_key = serialization.load_pem_public_key(
            key_file.read(),
            backend=default_backend()
        )
    return public_key

# 检查是否存在密钥文件，如果不存在则生成新的密钥对
if not (os.path.exists("private_key.pem") and os.path.exists("public_key.pem")):
    generate_keys()

# 加载密钥
private_key = load_private_key()
public_key = load_public_key()

def encrypt(message):
    # 加密消息
    message_bytes = message.encode('utf-8')
    encrypted_message = public_key.encrypt(
        message_bytes,
        padding.OAEP(
            mgf=padding.MGF1(algorithm=hashes.SHA256()),
            algorithm=hashes.SHA256(),
            label=None
        )   
    )
    return encrypted_message

def decrypt(encrypted_message):
    # 解密消息
    decrypted_message_bytes = private_key.decrypt(
        encrypted_message,
        padding.OAEP(
            mgf=padding.MGF1(algorithm=hashes.SHA256()),
            algorithm=hashes.SHA256(),
            label=None
        )
    )
    decrypted_message = decrypted_message_bytes.decode('utf-8')
    return decrypted_message

def get_rsa_public_key():
    return public_key