HTTP Basic Auth¶

对于最简单的情况，你可以使用 HTTP Basic Auth。

在 HTTP Basic Auth 中，应用程序期望一个包含用户名和密码的请求头。

如果未收到，则返回 HTTP 401 "Unauthorized" 错误。

并返回一个 WWW-Authenticate 头，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。

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请求头中。

简单的 HTTP Basic Auth¶

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 与依赖项一起使用。
它返回一个 HTTPBasicCredentials 类型的对象。
- 它包含发送的 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“执行”按钮）时，浏览器会要求你输入用户名和密码。

检查用户名¶

这是一个更完整的例子。

使用依赖项检查用户名和密码是否正确。

为此，请使用 Python 标准模块 secrets 检查用户名和密码。

secrets.compare_digest() 需要接收 bytes 或仅包含 ASCII 字符（英文字符）的 str，这意味着它不能处理 á（如 Sebastián）之类的字符。

为了解决这个问题，我们首先使用 UTF-8 编码将 username 和 password 转换为 bytes。

然后我们可以使用 secrets.compare_digest() 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
    ...

但是通过使用 secrets.compare_digest()，它将能抵御一种被称为“计时攻击”的攻击。

计时攻击¶

但是什么是“计时攻击”？

我们来想象一下，一些攻击者正在尝试猜测用户名和密码。

他们发送了一个用户名 johndoe 和密码 love123 的请求。

然后你的应用程序中的 Python 代码将等同于以下内容：

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

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

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以下的操作

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

Python 必须比较 stanleyjobsox 和 stanleyjobson 中完整的 stanleyjobso，然后才能发现两个字符串不相同。因此，它会多花几微秒才能回复“用户名或密码不正确”。

响应时间帮助攻击者¶

届时，攻击者通过注意到服务器发送“不正确的用户名或密码”响应所花费的时间多出几微秒，就会知道他们 *某些地方* 是正确的，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。

一次“专业”的攻击¶

当然，攻击者不会手动尝试这一切，他们会编写一个程序来完成，可能每秒进行数千甚至数百万次测试。他们一次只会获得一个额外的正确字母。

但是，通过这样做，在几分钟或几小时内，攻击者将猜出正确的用户名和密码，在我们的应用程序的“帮助”下，仅仅利用响应时间。

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 所需的时间相同。密码也是如此。

这样，在您的应用程序代码中使用 secrets.compare_digest() 将可以安全地抵御所有这些范围的安全攻击。

返回错误¶

在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状态码相同），并添加 WWW-Authenticate 请求头，使浏览器再次显示登录提示。

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 Basic Auth¶

简单的 HTTP Basic Auth¶

检查用户名¶

计时攻击¶

响应时间帮助攻击者¶

一次“专业”的攻击¶

用 secrets.compare_digest() 修复¶

返回错误¶

用 `secrets.compare_digest()` 修复¶