<?php

declare (strict_types=1);
/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2021 Spomky-Labs
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */
namespace RSSProVendor\Cose\Algorithm\Mac;

use RSSProVendor\Assert\Assertion;
use RSSProVendor\Cose\Key\Key;
abstract class Hmac implements Mac
{
    public function hash(string $data, Key $key): string
    {
        $this->checKey($key);
        $signature = hash_hmac($this->getHashAlgorithm(), $data, $key->get(-1), \true);
        return mb_substr($signature, 0, intdiv($this->getSignatureLength(), 8), '8bit');
    }
    public function verify(string $data, Key $key, string $signature): bool
    {
        return hash_equals($this->hash($data, $key), $signature);
    }
    abstract protected function getHashAlgorithm(): string;
    abstract protected function getSignatureLength(): int;
    private function checKey(Key $key): void
    {
        Assertion::eq($key->type(), 4, 'Invalid key. Must be of type symmetric');
        Assertion::true($key->has(-1), 'Invalid key. The value of the key is missing');
    }
}
