HTTP 基本认证¶

对于最简单的情况，你可以使用 HTTP 基本认证。

在 HTTP 基本认证中，应用程序期望一个包含用户名和密码的 HTTP 头。

如果未收到，则返回 HTTP 401 "Unauthorized"（未授权）错误。

并返回一个 WWW-Authenticate 头，其值为 Basic，以及一个可选的 realm 参数。

这会告诉浏览器显示集成的用户名和密码提示框。

然后，当你输入用户名和密码后，浏览器会自动将它们发送到 HTTP 头中。

简单的 HTTP 基本认证¶

导入 HTTPBasic 和 HTTPBasicCredentials。
使用 HTTPBasic 创建一个 “security 方案”。
在你的路径操作中，将该 security 用于一个依赖。
它会返回一个 HTTPBasicCredentials 类型的对象。
- 该对象包含发送的 username 和 password。

Python 3.9+

from typing import Annotated

from fastapi import Depends, FastAPI
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


@app.get("/users/me")
def read_current_user(credentials: Annotated[HTTPBasicCredentials, Depends(security)]):
    return {"username": credentials.username, "password": credentials.password}

🤓 其他版本和变体

Python 3.8+Python 3.8+ - 非 Annotated

from fastapi import Depends, FastAPI
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from typing_extensions import Annotated

app = FastAPI()

security = HTTPBasic()


@app.get("/users/me")
def read_current_user(credentials: Annotated[HTTPBasicCredentials, Depends(security)]):
    return {"username": credentials.username, "password": credentials.password}

提示

如果可能，请优先使用 Annotated 版本。

from fastapi import Depends, FastAPI
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


@app.get("/users/me")
def read_current_user(credentials: HTTPBasicCredentials = Depends(security)):
    return {"username": credentials.username, "password": credentials.password}

当你第一次尝试打开 URL（或点击文档中的“Execute”按钮）时，浏览器会要求你输入用户名和密码

检查用户名¶

这是一个更完整的示例。

使用依赖项来检查用户名和密码是否正确。

为此，请使用 Python 标准模块 secrets 来检查用户名和密码。

secrets.compare_digest() 需要接受 bytes 或仅包含 ASCII 字符（英文字符）的 str，这意味着它不适用于像 á（如 Sebastián）这样的字符。

为了处理这种情况，我们首先将 username 和 password 编码为 UTF-8 格式的 bytes。

然后我们可以使用 secrets.compare_digest() 来确保 credentials.username 是 "stanleyjobson"，并且 credentials.password 是 "swordfish"。

Python 3.9+

import secrets
from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


def get_current_username(
    credentials: Annotated[HTTPBasicCredentials, Depends(security)],
):
    current_username_bytes = credentials.username.encode("utf8")
    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username


@app.get("/users/me")
def read_current_user(username: Annotated[str, Depends(get_current_username)]):
    return {"username": username}

🤓 其他版本和变体

Python 3.8+Python 3.8+ - 非 Annotated

import secrets

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from typing_extensions import Annotated

app = FastAPI()

security = HTTPBasic()


def get_current_username(
    credentials: Annotated[HTTPBasicCredentials, Depends(security)],
):
    current_username_bytes = credentials.username.encode("utf8")
    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username


@app.get("/users/me")
def read_current_user(username: Annotated[str, Depends(get_current_username)]):
    return {"username": username}

提示

如果可能，请优先使用 Annotated 版本。

import secrets

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


def get_current_username(credentials: HTTPBasicCredentials = Depends(security)):
    current_username_bytes = credentials.username.encode("utf8")
    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username


@app.get("/users/me")
def read_current_user(username: str = Depends(get_current_username)):
    return {"username": username}

这类似于

if not (credentials.username == "stanleyjobson") or not (credentials.password == "swordfish"):
    # Return some error
    ...

但通过使用 secrets.compare_digest()，它将能抵御一种称为“时序攻击”的攻击。

时序攻击¶

但什么是“时序攻击”？

让我们想象一些攻击者正在尝试猜测用户名和密码。

他们发送了一个请求，其中包含用户名 johndoe 和密码 love123。

那么你的应用程序中的 Python 代码将等同于类似这样的内容：

if "johndoe" == "stanleyjobson" and "love123" == "swordfish":
    ...

但是当 Python 比较 johndoe 中的第一个 j 和 stanleyjobson 中的第一个 s 时，它会立即返回 False，因为它已经知道这两个字符串不相同，认为“没有必要浪费更多计算来比较其余的字母”。然后你的应用程序会说“用户名或密码不正确”。

但随后攻击者尝试使用用户名 stanleyjobsox 和密码 love123。

你的应用程序代码会执行类似这样的操作：

if "stanleyjobsox" == "stanleyjobson" and "love123" == "swordfish":
    ...

Python 必须比较 stanleyjobsox 和 stanleyjobson 中完整的 stanleyjobso 部分，才能意识到这两个字符串不相同。因此，回复“用户名或密码不正确”会多花费几微秒。

响应时间会帮助攻击者¶

此时，攻击者通过注意到服务器发送“用户名或密码不正确”响应所需的时间多了几微秒，就会知道他们某种程度上猜对了，一些初始字母是正确的。

然后他们可以再次尝试，知道它可能更类似于 stanleyjobsox 而不是 johndoe。

“专业”攻击¶

当然，攻击者不会手动尝试这一切，他们会编写程序来完成，可能每秒进行数千或数百万次测试。他们每次只会猜对一个额外的字母。

但是通过这样做，在几分钟或几小时内，攻击者就能猜出正确的用户名和密码，这得益于我们应用程序的“帮助”，仅仅利用了响应时间。

使用 `secrets.compare_digest()` 修复¶

但在我们的代码中，我们实际上使用了 secrets.compare_digest()。

简而言之，比较 stanleyjobsox 和 stanleyjobson 所需的时间，与比较 johndoe 和 stanleyjobson 所需的时间是相同的。密码也是如此。

这样，在应用程序代码中使用 secrets.compare_digest()，就可以安全地抵御所有这些安全攻击。

返回错误¶

检测到凭据不正确后，返回一个状态码为 401 的 HTTPException（与未提供凭据时返回的相同），并添加 WWW-Authenticate 头部，以使浏览器再次显示登录提示框。

Python 3.9+

import secrets
from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


def get_current_username(
    credentials: Annotated[HTTPBasicCredentials, Depends(security)],
):
    current_username_bytes = credentials.username.encode("utf8")
    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username


@app.get("/users/me")
def read_current_user(username: Annotated[str, Depends(get_current_username)]):
    return {"username": username}

🤓 其他版本和变体

Python 3.8+Python 3.8+ - 非 Annotated

import secrets

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from typing_extensions import Annotated

app = FastAPI()

security = HTTPBasic()


def get_current_username(
    credentials: Annotated[HTTPBasicCredentials, Depends(security)],
):
    current_username_bytes = credentials.username.encode("utf8")
    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username


@app.get("/users/me")
def read_current_user(username: Annotated[str, Depends(get_current_username)]):
    return {"username": username}

提示

如果可能，请优先使用 Annotated 版本。

import secrets

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


def get_current_username(credentials: HTTPBasicCredentials = Depends(security)):
    current_username_bytes = credentials.username.encode("utf8")
    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username


@app.get("/users/me")
def read_current_user(username: str = Depends(get_current_username)):
    return {"username": username}

HTTP 基本认证¶

简单的 HTTP 基本认证¶

检查用户名¶

时序攻击¶

响应时间会帮助攻击者¶

“专业”攻击¶

使用 secrets.compare_digest() 修复¶

返回错误¶

使用 `secrets.compare_digest()` 修复¶