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请求头。

如果未收到该请求头，它将返回一个 HTTP 401 "未授权" 错误。

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

这会告诉浏览器显示一个用于输入用户名和密码的集成提示。

然后，当你输入用户名和密码时，浏览器会自动将它们发送在请求头中。

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 中使用该 security 作为依赖项。
它返回一个 HTTPBasicCredentials 类型的对象：
- 该对象包含发送的用户名和密码。

Python 3.9+Python 3.8+Python 3.8+ 非注解版本

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}

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

如果可能，建议使用 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该 URL（或在文档中点击 "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¶

这里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() 需要接受 bytes 或仅包含 ASCII 字符（即英文中的字符）的 str，这意味着它无法处理像 á 这样的字符，例如 Sebastián。

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

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+Python 3.8+Python 3.8+ 非注解版本

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}

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

如果可能，建议使用 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"):
    # 返回一些错误
    ...

但通过使用 secrets.compare_digest()，它将能够抵御一种称为 "计时攻击" 的攻击。

计时攻击¶

但什么是 "计时攻击" 呢？

假设一些攻击者正在尝试猜测用户名和密码。

他们发送一个包含用户名 johndoe 和密码 love123 的请求。

然后你的应用程序中的 Python 代码将类似于：

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

但在 Python 比较 johndoe 中的第一个 j 和 stanleyjobson 中的第一个 s 的那一刻，它会返回 False，因为它已经知道这两个字符串不同，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做类似的事情：

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

Python 将不得不比较 stanleyjobsox 和 stanleyjobson 中的整个 stanleyjobso，然后才意识到这两个字符串不同。因此，它将花费一些额外的微秒时间来回复 "用户名或密码不正确"。

响应时间帮助了攻击者¶

在这一点上，通过注意到服务器花费了更长时间来发送 "用户名或密码不正确" 的响应，攻击者将知道他们猜对了 某些东西，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所有这些，他们会编写一个程序来完成，可能每秒进行数千或数百万次测试。并且每次只猜对一个额外的字母。

但通过这样做，在几分钟或几小时内，攻击者将猜出正确的用户名和密码，借助我们的应用程序，仅仅通过响应时间来帮助他们。

使用 `secrets.compare_digest()` 修复¶

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

简而言之，将 stanleyjobsox 与 stanleyjobson 进行比较所需的时间与将 johndoe 与 stanleyjobson 进行比较所需的时间相同。密码的比较也是如此。

这样一来，在你的应用程序代码中使用 secrets.compare_digest()，就能安全抵御这一系列的安全攻击。

返回错误¶

在检测到凭证不正确后，返回一个状态码为 401 的 HTTPException（与未提供凭证时返回的状态码相同），并添加 WWW-Authenticate 头，使浏览器再次显示登录提示：

Python 3.9+Python 3.8+Python 3.8+ non-Annotated

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}

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

如果可能，建议使用 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¶

计时攻击¶

响应时间帮助了攻击者¶

一次 "专业" 的攻击¶

使用 secrets.compare_digest() 修复¶

返回错误¶

使用 `secrets.compare_digest()` 修复¶