# API v3密钥

为了保证安全性，微信支付在**回调通知**和**平台证书**下载接口中，对关键信息进行了`AES-256-GCM`加密。API v3密钥是加密时使用的对称密钥。

商户需先在【商户平台】->【API安全】的页面设置该密钥，请求才能通过微信支付的签名校验。密钥的长度为32个字节。

{% hint style="info" %}
APIv3密钥与API密钥是隔离的，设置该密钥时，不会导致API密钥发生变化。
{% endhint %}

{% hint style="warning" %}
APIv3密钥属于敏感信息，请妥善保管不要泄露，如果怀疑信息泄露，请重设密钥。
{% endhint %}


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://wechatpay-api.gitbook.io/wechatpay-api-v3/ren-zheng/api-v3-mi-yao.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.