```Python hl_lines="1  11-13"
{!../../../docs_src/security/tutorial007.py!}
```

这段代码确保 `credentials.username` 是 `"stanleyjobson"`，且 `credentials.password` 是`"swordfish"`。与以下代码类似：

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

但使用 `secrets.compare_digest()`，可以防御**时差攻击**，更加安全。

### 时差攻击

什么是**时差攻击**？

Um dies zu lösen, konvertieren wir zunächst den `username` und das `password` in UTF-8-codierte `bytes`.

Dann können wir `secrets.compare_digest()` verwenden, um sicherzustellen, dass `credentials.username` `"stanleyjobson"` und `credentials.password` `"swordfish"` ist.

=== "Python 3.9+"

    ```Python hl_lines="1  12-24"
    {!> ../../../docs_src/security/tutorial007_an_py39.py!}

If it doesn't receive it, it returns an HTTP 401 "Unauthorized" error.

And returns a header `WWW-Authenticate` with a value of `Basic`, and an optional `realm` parameter.

That tells the browser to show the integrated prompt for a username and password.

Then, when you type that username and password, the browser sends them in the header automatically.

🍵 👈, 👥 🥇 🗜 `username` & `password` `bytes` 🔢 👫 ⏮️ 🔠-8️⃣.

⤴️ 👥 💪 ⚙️ `secrets.compare_digest()` 🚚 👈 `credentials.username` `"stanleyjobson"`, & 👈 `credentials.password` `"swordfish"`.

```Python hl_lines="1  11-21"
{!../../../docs_src/security/tutorial007.py!}
```

👉 🔜 🎏:

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