<?php

function urlsafe_b64decode($string) {

    $data = str_replace(array('-','_'),array('+','/'),$string);

    $mod4 = strlen($data) % 4;

    if ($mod4) {

        $data .= substr('====', $mod4);

    }

    return base64_decode($data);

}

function decode($final_message, $e_key, $i_key) {

    $enc_price = urlsafe_b64decode($final_message);

    $iv = substr($enc_price, 0, 16);

    $p = substr($enc_price, 16, 8);

    $sig = substr($enc_price, 24, 4);

    $price_pad = hash_hmac("sha1", $iv, $e_key, true);

    $price = $p ^ $price_pad;

    $conf_sig = hash_hmac("sha1", $price . $iv, $i_key, true);

    if ($conf_sig != $sig) {

        return false;

    }

    return $price;

}

$e_key = "encrypriceencodingwhenintegratin";

$i_key = "integpriceencodingwhenintegratin";

foreach(["cHJpY2VlbmNvZGluZ3doZTzUyMb2dirzYcjALQ", "cHJpY2VlbmNvZGluZ3doZTjUy8b2dirzYXcL0Q", "cHJpY2VlbmNvZGluZ3doZTzKyOjDQx_zjiVOmw", "cHJpY2VlbmNvZGluZ3doZTrN1vbBdirz1G52-Q"] as $msg) {

    echo decode($msg, $e_key, $i_key) . PHP_EOL;

}