payment/app/Helper/OmiPay/Signer.php

<?php

declare(strict_types=1);

namespace App\Helper\OmiPay;

class Signer
{
    public static function sign($params) {
        $mNumber = $params['m_number'] ?? '';
        $mNumber = $mNumber ? $mNumber : Config::get('app_id');
        $signString =  $mNumber . '&'
        . $params['timestamp'] . '&'
        . $params['nonce_str'] . '&'
        . Config::get('secret_key');
        return strtoupper(md5($signString));
    }

    public static function verify($params) {
        $sign = $params['sign'] ?? '';
        return $sign == self::sign($params);
    }
}