How to remove HMAC-Sha1 signature from JSON data?

Question

PHP

Good afternoon. I am creating a signature for the merchant and there was such a problem.
It is necessary to remove the HMAC-Sha1 signature from the transmitted JSON data (byte array) and then transfer that signature back to the byte array.
The question is how to translate json data into an array of bytes? And do I need to translate something at all, maybe I misunderstood?

$data = array(
  "test" => 123,
  "test2" => 123
);
$key = "123123123";

$hash =  hash_hmac("sha1", $data, $key, $raw_output=TRUE);

Answer 1

Read the documentation.
It is possible that in general it is necessary to do through pack ().
UPD: Generate json data and then remove the signature from this line.