# crypto.hmac_sha256

## Function

Generate an HMAC-SHA256 signature of the current text using the key.

## Syntax

```bt
crypto(text).hmac_sha256(key)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| key | String | Yes | None | HMAC key. |

## Return value

| Type | Description |
| ------ | ------ |
| String | HMAC-SHA256 lowercase hexadecimal signature. |

## Code Example

```bt
result = crypto('payload').hmac_sha256('secret')

// Output: b82fcb791acec57859b989b430a826488ce2e479fdf92326bd0a2e8375a42ba4
print result
```

## Notes

- Both text and keys participate in the calculation as UTF-8 bytes.