function sodium_decrypt( $webhookSecret, $iv_from_http_header, $http_body , $auth_tag_from_http_header ){
	$key = mb_convert_encoding($webhookSecret, "UTF-8", "BASE64");
	$iv = mb_convert_encoding($iv_from_http_header, "UTF-8", "BASE64");
	$cipher_text = mb_convert_encoding($http_body, "UTF-8", "BASE64") . mb_convert_encoding($auth_tag_from_http_header, "UTF-8", "BASE64");

	$result = sodium_crypto_aead_aes256gcm_decrypt($cipher_text, "", $iv, $key);

	return $result;

}

$webhookSecret = "6fNDiYU0T0/evFpmfycNai/AqF24i+rT0OmuVw0/sGQ=";
$iv_from_http_header = "RYjpCMtUmK54T6Lk";
$auth_tag_from_http_header = "FUajWHmZjP4A5qaa1G0kxw==";
$http_body = "9bIjURJIcwoKvQr+ifOTH3HbMX+IqmsRqHuG/I1GfbSX89JE5DcWh/p8QROC5pRAuYZ7" .
"ln7RSkHXJdZpVz1LFQ2859WsetvHHui7qYmfxATOO1j0AQuPdAD3FeRH0kR4s/v3c2nV8" .
"1DnUXFCnQER/+VWrYdbu5vn8gm+diSE6CHvkK+ODy0ebVi5O6VBnWVjgBUG33VwWiAyIl" .
"7Ik435V55WnZgynH3GfbVYoGwZ5UhYtn3yw2yruiLAKu6VTBvnh/ZJP21cHCJSF6NPSd+8" .
"1gzWFU/+ECm3cf3uBbCkmKmL7HxRhRxhG0lMtX6ELZOXuw3eDJ1BTu+sSMkV/5Xk+5XX48" .
"XmP6CGZ7KmP7Q3Fw1kZmhn0unFyv0Gw8PjT1Ohny/HMgNl16I=";

// Decrypt message
$result = sodium_decrypt($webhookSecret, $iv_from_http_header, $http_body , $auth_tag_from_http_header);

print($result);