HTTP 基本认证¶

对于最简单的场景，你可以使用 HTTP 基本认证。

在 HTTP 基本认证中，应用程序期望收到包含用户名和密码的请求头。

如果未收到该请求头，则返回 HTTP 401 "Unauthorized" 错误。

并返回值为 Basic 的 WWW-Authenticate 头，以及可选的 realm 参数。

这会告知浏览器显示集成式的用户名和密码输入提示。

然后，当你输入用户名和密码时，浏览器会自动将其包含在请求头中发送。

简单 HTTP 基本认证¶

导入 HTTPBasic 和 HTTPBasicCredentials。
使用 HTTPBasic 创建一个“安全方案”。
在路径操作中使用该 security 作为依赖项。
它返回一个 HTTPBasicCredentials 类型的对象：
- 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}

🤓 Other versions and variants

Python 3.8+Python 3.8+ - non-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}

Tip

Prefer to use the Annotated version if possible.

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}

当你首次尝试打开该 URL（或在文档中点击 "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，使用 Python 标准模块 secrets 来检查用户名和密码。

secrets.compare_digest() 需要接收 bytes 或仅包含 ASCII 字符（英文字符）的 str，这意味着它无法处理像 Sebastián 中的 á 这样的字符。

为了处理这种情况，我们首先将 username 和 password 转换为使用 UTF-8 编码的 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}

🤓 Other versions and variants

Python 3.8+Python 3.8+ - non-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}

Tip

Prefer to use the Annotated version if possible.

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"):
    # 返回某些错误
    ...

但通过使用 secrets.compare_digest()，可以防范一种称为“计时攻击”的攻击方式。

计时攻击¶

但什么是“计时攻击”呢？

假设一些攻击者试图猜测用户名和密码。

他们发送一个用户名为 johndoe、密码为 love123 的请求。

那么你应用程序中的 Python 代码将等效于类似以下内容：

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

但在 Python 将 johndoe 的第一个字母 j 与 stanleyjobson 的第一个字母 s 进行比较时，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资源来比较其余字母”。然后你的应用程序会返回“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以下操作：

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

Python 将不得不比较 stanleyjobsox 和 stanleyjobson 中的整个 stanleyjobso 部分，然后才会意识到两个字符串并不相同。因此，它将花费额外的微秒来回复“用户名或密码不正确”。

响应时间帮助了攻击者¶

此时，通过注意到服务器花费了稍长一些的微秒时间来发送“用户名或密码不正确”的响应，攻击者将知道他们猜对了_某些内容_，部分起始字母是正确的。

然后他们可以再次尝试，知道正确的用户名可能更接近 stanleyjobsox 而不是 johndoe。

“专业”攻击¶

当然，攻击者不会手动进行所有这些尝试，他们会编写程序来完成，可能每秒进行数千次甚至数百万次测试。并且他们每次只能猜对一个额外的字母。

但通过这种方式，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，并在我们应用程序的“帮助”下，仅利用响应所花费的时间就实现了这一目的。

使用 `secrets.compare_digest()` 修复此问题¶

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

简而言之，比较 stanleyjobsox 和 stanleyjobson 所花费的时间，与比较 johndoe 和 stanleyjobson 所花费的时间相同。密码的比较也是如此。

这样，在你的应用程序代码中使用 secrets.compare_digest()，就能防范此类安全攻击。

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状态码相同），并添加 WWW-Authenticate 头以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}

🤓 Other versions and variants

Python 3.8+Python 3.8+ - non-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}

Tip

Prefer to use the Annotated version if possible.

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 HTTP 基本认证¶

检查用户名¶

计时攻击¶

响应时间帮助了攻击者¶

“专业”攻击¶

使用 secrets.compare_digest() 修复此问题¶

返回错误¶

使用 `secrets.compare_digest()` 修复此问题¶