001/**
002 *
003 * Copyright 2003-2007 Jive Software, 2016-2021 Florian Schmaus.
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smack.util;
018
019import java.security.SecureRandom;
020import java.util.Random;
021
022public class RandomUtil {
023
024    static final ThreadLocal<SecureRandom> SECURE_RANDOM = new ThreadLocal<SecureRandom>() {
025        @Override
026        protected SecureRandom initialValue() {
027            return new SecureRandom();
028        }
029    };
030
031    /**
032     * Pseudo-random number generator object for use with randomString().
033     * The Random class is not considered to be cryptographically secure, so
034     * only use these random Strings for low to medium security applications.
035     */
036    static final ThreadLocal<Random> RANDOM = new ThreadLocal<Random>() {
037        @Override
038        protected Random initialValue() {
039            return new Random();
040        }
041    };
042
043    public static int nextSecureRandomInt(int bound) {
044        return SECURE_RANDOM.get().nextInt(bound);
045    }
046
047    public static int nextSecureRandomInt() {
048        return SECURE_RANDOM.get().nextInt();
049    }
050
051    public static void fillWithSecureRandom(byte[] bytes) {
052        SECURE_RANDOM.get().nextBytes(bytes);
053    }
054}