PHP server side google play signature validation

google_play_validator.php

<?php
$prefix = "-----BEGIN PUBLIC KEY-----\n";
$surfix = '-----END PUBLIC KEY-----';
$key = "your google play pub key";

$key =$prefix . chunk_split($key, 64, "\n") . $surfix;
$key = openssl_get_publickey($key);
if (false === $key) {
  echo "invalid public key\n";
	return;
}

$data_str = '{data string returned by google play}';
$signature = '{signature returned by google play}';

$validate = openssl_verify($data_str, base64_decode($signature), $key);
if(1 != $validate){ //invalid signature
	echo "mojo_invalid_signature\n";
} else {
 	echo "success\n";	
}