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, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18 package org.apache.commons.crypto.random;
19
20 import java.security.NoSuchAlgorithmException;
21 import java.security.SecureRandom;
22 import java.util.Properties;
23
24 import org.apache.commons.crypto.utils.Utils;
25
26 /**
27 * A CryptoRandom of Java implementation.
28 * <p>
29 * This class is not public/protected so does not appear in the main Javadoc Please ensure that property use is documented in the enum
30 * CryptoRandomFactory.RandomProvider
31 * </p>
32 */
33 final class JavaCryptoRandom implements CryptoRandom {
34
35 private final SecureRandom instance;
36
37 /**
38 * Constructs a {@link JavaCryptoRandom}.
39 *
40 * @param properties the configuration properties. Uses the key {@link CryptoRandomFactory#JAVA_ALGORITHM_KEY} to get the name of the algorithm, with a
41 * default of {@link CryptoRandomFactory#JAVA_ALGORITHM_DEFAULT}
42 */
43 public JavaCryptoRandom(final Properties properties) {
44 SecureRandom tmp;
45 try {
46 tmp = SecureRandom.getInstance(properties.getProperty(CryptoRandomFactory.JAVA_ALGORITHM_KEY, CryptoRandomFactory.JAVA_ALGORITHM_DEFAULT));
47 } catch (final NoSuchAlgorithmException e) {
48 tmp = new SecureRandom();
49 }
50 instance = tmp;
51 }
52
53 /**
54 * Overrides {@link java.lang.AutoCloseable#close()}. For {@link JavaCryptoRandom}, we don't need to recycle resource.
55 */
56 @Override
57 public void close() {
58 // do nothing
59 }
60
61 /**
62 * Overrides Random#next(). Generates an integer containing the user-specified number of random bits(right justified, with leading zeros).
63 *
64 * @param numBits number of random bits to be generated, where 0 {@literal <=} {@code numBits} {@literal <=} 32.
65 * @return int an {@code int} containing the user-specified number of random bits (right justified, with leading zeros).
66 */
67 protected int next(final int numBits) {
68 Utils.checkArgument(numBits >= 0 && numBits <= 32);
69 // Can't simply invoke instance.next(bits) here, because that is package protected.
70 // But, this should do.
71 return instance.nextInt() >>> (Integer.SIZE - numBits);
72 }
73
74 /**
75 * Overrides {@link CryptoRandom#nextBytes(byte[])}. Generates random bytes and places them into a user-supplied byte array. The number of random bytes
76 * produced is equal to the length of the byte array.
77 *
78 * @param bytes the array to be filled in with random bytes.
79 */
80 @Override
81 public void nextBytes(final byte[] bytes) {
82 instance.nextBytes(bytes);
83 }
84 }