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administrator/components/com_akeebabackup/webpush/ECC/ModularArithmetic.php

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+<?php
+/**
+ * Akeeba WebPush
+ *
+ * An abstraction layer for easier implementation of WebPush in Joomla components.
+ *
+ * @copyright (c) 2022 Akeeba Ltd
+ * @license   GNU GPL v3 or later; see LICENSE.txt
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace Akeeba\WebPush\ECC;
+
+use Brick\Math\BigInteger;
+
+/**
+ * This class is copied verbatim from the JWT Framework by Spomky Labs.
+ *
+ * You can find the original code at https://github.com/web-token/jwt-framework
+ *
+ * The original file has the following copyright notice:
+ *
+ * =====================================================================================================================
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2014-2020 Spomky-Labs
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE-SPOMKY.txt file for details.
+ *
+ * =====================================================================================================================
+ *
+ * @internal
+ */
+class ModularArithmetic
+{
+    public static function sub(BigInteger $minuend, BigInteger $subtrahend, BigInteger $modulus): BigInteger
+    {
+        return $minuend->minus($subtrahend)->mod($modulus);
+    }
+
+    public static function mul(BigInteger $multiplier, BigInteger $muliplicand, BigInteger $modulus): BigInteger
+    {
+        return $multiplier->multipliedBy($muliplicand)->mod($modulus);
+    }
+
+    public static function div(BigInteger $dividend, BigInteger $divisor, BigInteger $modulus): BigInteger
+    {
+        return self::mul($dividend, Math::inverseMod($divisor, $modulus), $modulus);
+    }
+}