[flask]使用mTLS双向加密认证http通信

前言

mTLS，全称为双向TLS（Mutual Transport Layer Security），是一种安全通信协议，确保通信双方在传输层进行身份验证。与单向HTTPS不同，吗TLS不仅要求客户端验证服务端的身份，还要求服务端验证客户端的身份。

PS：本文实验环境为OpenSSL 3.0.11 + Python 3.11 + Flask 3.0.2，自测python 3.8 + openssl 1.1会有问题。

生成证书

常见的证书生成方式就是自签名证书，有条件的话还是自建CA机构或者购买专门的证书。

1. 生成ca根证书。生成过程中会提示填写密码，记住密码，后续会用到。这里直接声明Common Name为qw.er.com，可根据实际需求修改ON、OU、CN等信息。

openssl req -x509 -newkey rsa:4096 -keyout ca.key -out ca.crt -subj "/CN=qw.er.com"  -days 3650

2. 新建并编辑openssl.cnf文件，根据实际需求修改CN、CN等信息

[req]
req_extensions = v3_req
distinguished_name = req_distinguished_name
prompt = no

[req_distinguished_name]
countryName = CN
stateOrProvinceName = Anhui
localityName = Hefei
organizationName = zhangsan
commonName = qw.er.com

[v3_req]
subjectAltName = @alt_names

[alt_names]
DNS.1 = qw.er.com

3. 创建服务端证书。生成私钥文件时会提示输入根证书密码。

openssl req -newkey rsa:2048 -nodes -keyout server.key -out server.csr -subj "/CN=qw.er.com" -config openssl.cnf
openssl x509 -req -in server.csr -out server.crt -CA ca.crt -CAkey ca.key -CAcreateserial -days 365 -extensions v3_req -extfile openssl.cnf

4. 创建客户端证书。生成私钥文件时会提示输入根证书密码

openssl req -newkey rsa:2048 -nodes -keyout client.key -out client.csr -subj "/CN=qw.er.com" -config openssl.cnf
openssl x509 -req -in client.csr -out client.crt -CA ca.crt -CAkey ca.key -CAcreateserial -days 365 -extensions v3_req -extfile openssl.cnf

服务端示例

除了flask本身，只需要导入标准库ssl。注意证书路径需要是绝对路径。

from flask import Flask
import ssl

app = Flask(__name__)

@app.get("/health")
def health():
    return "ok"

def get_ssl_context():
    ca_crt_path = "/home/atlas/workspace/flask-learn/certs/ca.crt"
    server_crt = "/home/atlas/workspace/flask-learn/certs/server.crt"
    server_key = "/home/atlas/workspace/flask-learn/certs/server.key"
    password = "qwerasdf"

    context = ssl.SSLContext(protocol=ssl.PROTOCOL_TLS_SERVER)
    context.verify_mode = ssl.CERT_REQUIRED
    context.load_verify_locations(ca_crt_path)
    context.load_cert_chain(certfile=server_crt, keyfile=server_key, password=password)

    return context

if __name__ == "__main__":
    ssl_context = get_ssl_context()
    app.run(host="0.0.0.0", port=5000, ssl_context=ssl_context)

客户端示例

• 方式1：使用curl命令

curl -k --cacert ca.crt --key client.key --cert client.crt https://127.0.0.1:5000/health

• 方式2：使用requests库。注意修改hosts文件将qw.er.com映射到IP

import requests

ca_crt_path = "/home/atlas/workspace/flask-learn/certs/ca.crt"
client_crt = "/home/atlas/workspace/flask-learn/certs/client.crt"
client_key = "/home/atlas/workspace/flask-learn/certs/client.key"

url = "https://qw.er.com:5000/health"

resp = requests.get(url, cert=(client_crt, client_key), verify=ca_crt_path)
print(resp.status_code)
print(resp.text)

• 方式3：使用httpx库。注意修改hosts文件将qw.er.com映射到IP

import httpx
import ssl

def get_ssl_context():
    password = "qwerasdf"
	ca_crt_path = "/home/atlas/workspace/flask-learn/certs/ca.crt"
	client_crt = "/home/atlas/workspace/flask-learn/certs/client.crt"
	client_key = "/home/atlas/workspace/flask-learn/certs/client.key"
    context = ssl.SSLContext(protocol=ssl.PROTOCOL_TLS_CLIENT)
    context.verify_mode = ssl.CERT_REQUIRED
    context.load_verify_locations(ca_crt_path)
    context.load_cert_chain(certfile=client_crt, keyfile=client_key, password=password)

    return context

url = "https://qw.er.com:5000/health"

context = get_ssl_context()

with httpx.Client(verify=context) as client:
    resp = client.get(url)
    print(resp.status_code)
    print(resp.text)