PHP: ReferenceError: hash_hmac is not defined

In my php file, I’m trying to hash something, but hash isn’t defined. I have looked up why this may be and I’ve verified that I’m on PHP v7.

Here’s the code: image

The first two lines look okay.
The third and fourth lines are missing a semicolon.
Looks like you are using javascript syntax to create an array … try this instead

$data = ["hash" => $signature];