> For the complete documentation index, see [llms.txt](https://docs.orai.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.orai.io/developer-guides/vrf/security-remarks.md).

# Security Remarks

1\. The only accepted callback function is *fulfillRandomness*(bytes32 \_reqId, uint256 \_random) with the function selector being *0x1f1f897f*. This is required in order to avoid malicious callbacks.

2\. The *fulfillRandomness* function is able to verify the VRF value and minimize the amount of keep3rs that can fulfill data with the following check functions:

* `require(isFulfiller[msg.sender], "Must is fulfiller")` : fulfillRandomness function guarantees that only a fixed amount of keep3rs are able to fulfill data ;
* `require(isNode(validator), "Forbidden validator")`: The VRF value is guaranteed to be generated from Oraichain's validators.

3\. The gas limit is 800,000. This means that any fulfilling or callback request exceeding the limit amount can lead to tx getting reverted, at which case the blockchain oracle will ignore and refuse to execute such request.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

```
GET https://docs.orai.io/developer-guides/vrf/security-remarks.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.