1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.myfaces.lifecycle;
20
21 import java.math.BigInteger;
22 import java.security.NoSuchAlgorithmException;
23 import java.security.SecureRandom;
24 import java.util.concurrent.atomic.AtomicLong;
25
26 /**
27 *
28 * @author lu4242
29 */
30 class TokenGenerator
31 {
32 private final AtomicLong _count;
33
34 public TokenGenerator()
35 {
36 _count = new AtomicLong(_getSeed());
37 }
38
39 private static long _getSeed()
40 {
41 SecureRandom rng;
42 try
43 {
44 // try SHA1 first
45 rng = SecureRandom.getInstance("SHA1PRNG");
46 }
47 catch (NoSuchAlgorithmException e)
48 {
49 // SHA1 not present, so try the default (which could potentially not be
50 // cryptographically secure)
51 rng = new SecureRandom();
52 }
53
54 // use 48 bits for strength and fill them in
55 byte[] randomBytes = new byte[6];
56 rng.nextBytes(randomBytes);
57
58 // convert to a long
59 return new BigInteger(randomBytes).longValue();
60 }
61
62 /**
63 * Get the next token to be assigned to this request
64 *
65 * @return
66 */
67 String _getNextToken()
68 {
69 // atomically increment the value
70 long nextToken = _count.incrementAndGet();
71
72 // convert using base 36 because it is a fast efficient subset of base-64
73 return Long.toString(nextToken, 36);
74 }
75 }