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diff --git a/lib/public/security/isecurerandom.php b/lib/public/security/isecurerandom.php
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+++ b/lib/public/security/isecurerandom.php
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+<?php
+/**
+ * Copyright (c) 2014 Lukas Reschke <lukas@owncloud.com>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+namespace OCP\Security;
+
+/**
+ * Class SecureRandom provides a layer around RandomLib to generate
+ * secure random numbers.
+ *
+ * Usage:
+ * $rng = new \OC\Security\SecureRandom();
+ * $randomString = $rng->getMediumStrengthGenerator()->generateString(30);
+ *
+ * @package OCP\Security
+ */
+interface ISecureRandom {
+
+	/**
+	 * Convenience method to get a low strength random number generator.
+	 *
+	 * Low Strength should be used anywhere that random strings are needed
+	 * in a non-cryptographical setting. They are not strong enough to be
+	 * used as keys or salts. They are however useful for one-time use tokens.
+	 *
+	 * @return $this
+	 */
+	public function getLowStrengthGenerator();
+
+	/**
+	 * Convenience method to get a medium strength random number generator.
+	 *
+	 * Medium Strength should be used for most needs of a cryptographic nature.
+	 * They are strong enough to be used as keys and salts. However, they do
+	 * take some time and resources to generate, so they should not be over-used
+	 *
+	 * @return $this
+	 */
+	public function getMediumStrengthGenerator();
+
+	/**
+	 * Generate a random string of specified length.
+	 * @param string $length The length of the generated string
+	 * @param string $characters An optional list of characters to use
+	 * @return string
+	 * @throws \Exception
+	 */
+	public function generate($length, $characters = '');
+}