> For the complete documentation index, see [llms.txt](https://docs.aurinko.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aurinko.io/unified-apis/webhooks-api/authentication.md).

# Authentication

### Aurinko Signature Validation Steps

To verify that a request truly came from Aurinko, follow these four steps:

#### 1. Extract the Components

You will need three specific pieces of information from the incoming HTTP request:

* **Timestamp:** The value of the <mark style="color:red;">X-Aurinko-Request-Timestamp</mark> header.
* **Signature:** The value of the <mark style="color:red;">X-Aurinko-Signature</mark> header (this is your target for comparison).
* **Raw Body:** The exact, unparsed byte array of the request body.&#x20;

{% hint style="info" %}
**Note:** Do not use a JSON-deserialized object, as whitespace differences will cause the hash to fail.
{% endhint %}

#### 2. Create the Base String

Concatenate the version, the timestamp, and the raw body using <mark style="color:red;">a colon (:)</mark> as a delimiter.

* **Current Version:** v0
* **Format:** v0:{timestamp}:{raw\_body}

#### 3. Compute the HMAC SHA256 Hash

Using your <mark style="color:red;">Aurinko Signing Secret</mark> as the key, sign the base string created in Step 2.<br>

**Java Example:**

```java
final byte[] signData = org.apache.commons.lang3.ArrayUtils.addAll(
    ("v0:" + timestampSeconds + ":").getBytes(StandardCharsets.UTF_8),
    payloadBytes
);
```

{% hint style="info" %}
Then hash signData using HMAC SHA256 and your Signing Secret
{% endhint %}

#### 4. Compare and Verify

Compare your computed hash against the X-Aurinko-Signature header.

* **Match:** The request is authentic; proceed with processing.
* **Mismatch:** The request is invalid and should be discarded (return a 401 or 403 status).

#### Quick Reference Table

| <h4><strong>Element</strong></h4> | <h4><strong>Source</strong></h4>       |
| --------------------------------- | -------------------------------------- |
| **Version**                       | Static string v0                       |
| **Key**                           | Your unique **Aurinko Signing Secret** |
| **Algorithm**                     | HMAC SHA256                            |
| **Delimiter**                     | Colon :                                |

**Java example:**

```java
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import org.apache.commons.codec.binary.Hex;
import org.apache.commons.lang3.ArrayUtils;

public class AurinkoValidator {

    private static final String HMAC_ALGO = "HmacSHA256";
    private static final String VERSION = "v0";

    public boolean isValidRequest(String signingSecret, String timestamp, String headerSignature, byte[] rawBody) {
        try {
            // 1. Prepare the prefix: "v0:timestamp:"
            String prefix = VERSION + ":" + timestamp + ":";
            byte[] prefixBytes = prefix.getBytes(StandardCharsets.UTF_8);

            // 2. Concatenate prefix bytes with raw body bytes
            byte[] dataToSign = ArrayUtils.addAll(prefixBytes, rawBody);

            // 3. Initialize HMAC SHA256 with your Secret
            SecretKeySpec secretKeySpec = new SecretKeySpec(
                signingSecret.getBytes(StandardCharsets.UTF_8), 
                HMAC_ALGO
            );
            Mac mac = Mac.getInstance(HMAC_ALGO);
            mac.init(secretKeySpec);

            // 4. Compute the hash
            byte[] computedHashBytes = mac.doFinal(dataToSign);
            String computedSignature = Hex.encodeHexString(computedHashBytes);

            // 5. Compare computed signature with the header
            // Use MessageDigest.isEqual for a time-constant comparison (prevents timing attacks)
            return java.security.MessageDigest.isEqual(
                computedSignature.getBytes(StandardCharsets.UTF_8),
                headerSignature.getBytes(StandardCharsets.UTF_8)
            );

        } catch (Exception e) {
            // Log the error and reject the request
            return false;
        }
    }
}
```


---

# 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.aurinko.io/unified-apis/webhooks-api/authentication.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.