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<?php
declare(strict_types=1);
/*
* The MIT License (MIT)
*
* Copyright (c) 2014-2019 Spomky-Labs
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
*/
namespace OTPHP;
use Assert\Assertion;
final class HOTP extends OTP implements HOTPInterface
{
protected function __construct(?string $secret, int $counter, string $digest, int $digits)
{
parent::__construct($secret, $digest, $digits);
$this->setCounter($counter);
}
public static function create(?string $secret = null, int $counter = 0, string $digest = 'sha1', int $digits = 6): HOTPInterface
{
return new self($secret, $counter, $digest, $digits);
}
protected function setCounter(int $counter): void
{
$this->setParameter('counter', $counter);
}
public function getCounter(): int
{
return $this->getParameter('counter');
}
private function updateCounter(int $counter): void
{
$this->setCounter($counter);
}
public function getProvisioningUri(): string
{
return $this->generateURI('hotp', ['counter' => $this->getCounter()]);
}
/**
* If the counter is not provided, the OTP is verified at the actual counter.
*/
public function verify(string $otp, ?int $counter = null, ?int $window = null): bool
{
Assertion::greaterOrEqualThan($counter, 0, 'The counter must be at least 0.');
if (null === $counter) {
$counter = $this->getCounter();
} elseif ($counter < $this->getCounter()) {
return false;
}
return $this->verifyOtpWithWindow($otp, $counter, $window);
}
private function getWindow(?int $window): int
{
return abs($window ?? 0);
}
private function verifyOtpWithWindow(string $otp, int $counter, ?int $window): bool
{
$window = $this->getWindow($window);
for ($i = $counter; $i <= $counter + $window; ++$i) {
if ($this->compareOTP($this->at($i), $otp)) {
$this->updateCounter($i + 1);
return true;
}
}
return false;
}
/**
* @return array<string, mixed>
*/
protected function getParameterMap(): array
{
$v = array_merge(
parent::getParameterMap(),
['counter' => function ($value): int {
Assertion::greaterOrEqualThan((int) $value, 0, 'Counter must be at least 0.');
return (int) $value;
}]
);
return $v;
}
}
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