001/**
002 * Copyright 2005-2016 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.kim.sesn;
017
018import java.security.SecureRandom;
019
020/**
021 * This class generates a random string for creating Distributed Session Tickets 
022 * 
023 * @author Kuali Rice Team (rice.collab@kuali.org)
024 *
025 */
026public class SessionIdGenerator {
027
028    /** The array of printable characters to be used in our random string. */
029    private static final char[] PRINTABLE_CHARACTERS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ012345679"
030        .toCharArray();
031
032    private static final SecureRandom randomizer = new SecureRandom();
033
034    public static String getNewString() {
035        final byte[] random = getNewStringAsBytes();
036
037        return convertBytesToString(random);
038    }
039
040
041    private static byte[] getNewStringAsBytes() {
042        final byte[] random = new byte[40];
043
044        randomizer.nextBytes(random);
045        
046        return random;
047    }
048
049    private static String convertBytesToString(final byte[] random) {
050        final char[] output = new char[random.length];
051        for (int i = 0; i < random.length; i++) {
052            final int index = Math.abs(random[i] % PRINTABLE_CHARACTERS.length);
053            output[i] = PRINTABLE_CHARACTERS[index];
054        }
055
056        return new String(output);
057    }
058}