1 files changed, 48 insertions, 0 deletions
diff --git a/lib/private/Security/SecureRandom.php b/lib/private/Security/SecureRandom.php
new file mode 100644
index 00000000000..b2a3d19ce74
--- /dev/null
+++ b/lib/private/Security/SecureRandom.php
@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Security;
+
+use OCP\Security\ISecureRandom;
+
+/**
+ * Class SecureRandom provides a wrapper around the random_int function to generate
+ * secure random strings. For PHP 7 the native CSPRNG is used, older versions do
+ * use a fallback.
+ *
+ * Usage:
+ * \OC::$server->get(ISecureRandom::class)->generate(10);
+ * @package OC\Security
+ */
+class SecureRandom implements ISecureRandom {
+	/**
+	 * Generate a secure random string of specified length.
+	 * @param int $length The length of the generated string
+	 * @param string $characters An optional list of characters to use if no character list is
+	 *                           specified all valid base64 characters are used.
+	 * @throws \LengthException if an invalid length is requested
+	 */
+	public function generate(
+		int $length,
+		string $characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/',
+	): string {
+		if ($length <= 0) {
+			throw new \LengthException('Invalid length specified: ' . $length . ' must be bigger than 0');
+		}
+
+		$maxCharIndex = \strlen($characters) - 1;
+		$randomString = '';
+
+		while ($length > 0) {
+			$randomNumber = \random_int(0, $maxCharIndex);
+			$randomString .= $characters[$randomNumber];
+			$length--;
+		}
+		return $randomString;
+	}
+}