fix: generated passwords come from the platform CSPRNG

tests/Unit/Infrastructure/Adapter/In/Web/View/PasswordGeneratorUsesTheCsprngTest.php

@@ -0,0 +1,129 @@
+<?php
+
+/**
+ * sysPass
+ *
+ * @author nuxsmin
+ * @link https://syspass.org
+ * @copyright 2012-2024, Rubén Domínguez nuxsmin@$syspass.org
+ *
+ * This file is part of sysPass.
+ *
+ * sysPass 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.
+ *
+ * sysPass 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 sysPass.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace SP\Tests\Unit\Infrastructure\Adapter\In\Web\View;
+
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * The "Generate" button behind every password field in the application — an account's password, a
+ * user's, the master password, the administrator account the installer creates — is
+ * `sysPass.Util.password.random()`, in `public/js/app-util.min.js`. It used to draw each character
+ * with `Math.random()`, which is not a cryptographic generator: V8 seeds one xorshift128+ stream
+ * per context and its state is recoverable from a modest run of outputs, so passwords generated in
+ * a session were predictable from each other.
+ *
+ * These files are authored directly — there is no unminified source and no build step — so this
+ * asserts against what actually ships. It is a source check rather than a behavioural one because
+ * the alternative is asserting that output looks random, which is exactly the assertion that
+ * passes for a broken generator.
+ */
+#[Group('unitary')]
+class PasswordGeneratorUsesTheCsprngTest extends TestCase
+{
+    private const UTIL = REAL_APP_ROOT . '/public/js/app-util.min.js';
+
+    /**
+     * The generator draws from the platform CSPRNG.
+     */
+    #[Test]
+    public function theGeneratorDrawsFromTheCryptoApi(): void
+    {
+        self::assertStringContainsString(
+            'window.crypto.getRandomValues',
+            self::generator(),
+            'the password generator must draw from crypto.getRandomValues'
+        );
+    }
+
+    /**
+     * And from nothing else. Math.random() is still used elsewhere in this file to mint DOM element
+     * ids, which is a fine use for it, so this is scoped to the generator rather than the file.
+     */
+    #[Test]
+    public function theGeneratorDrawsFromNothingElse(): void
+    {
+        self::assertStringNotContainsString(
+            'Math.random',
+            self::generator(),
+            'the password generator must not fall back to Math.random'
+        );
+    }
+
+    /**
+     * Every character of the alphabet can be produced.
+     *
+     * The index was `Math.floor(Math.random() * (c.length - 1))`, which is exclusive at both ends
+     * of that multiplication — so the last character of the assembled charset could never appear.
+     * Which character that was depended on which classes were enabled, so it silently shrank the
+     * alphabet by one wherever the button was used.
+     */
+    #[Test]
+    public function theWholeAlphabetCanBeDrawn(): void
+    {
+        $generator = self::generator();
+
+        self::assertStringContainsString('d.randomIndex(c.length)', $generator);
+        self::assertStringNotContainsString('c.length-1', $generator);
+    }
+
+    /**
+     * The rejection loop cannot run forever.
+     *
+     * It regenerated the whole candidate until it satisfied every enabled character class. The
+     * length is set in the UI from an input whose `min` is 1, and the default complexity requires
+     * four classes, so any length below four made the condition unsatisfiable and the loop froze
+     * the tab.
+     */
+    #[Test]
+    public function theRejectionLoopIsBounded(): void
+    {
+        self::assertStringNotContainsString(
+            'do e=f();while(!m(e));',
+            self::generator(),
+            'the rejection loop must not be unbounded'
+        );
+    }
+
+    /**
+     * `sysPass.Util.password`'s generator, from `randomIndex` through to the end of `random()`.
+     */
+    private static function generator(): string
+    {
+        $source = (string)file_get_contents(self::UTIL);
+
+        $start = strpos($source, 'randomIndex:function');
+        self::assertNotFalse($start, 'the generator must define randomIndex');
+
+        $end = strpos($source, 'output:function', $start);
+        self::assertNotFalse($end, 'the generator must be followed by output()');
+
+        return substr($source, $start, $end - $start);
+    }
+}