StrongSeedReader.java revision 14374:2d42c4cfd5ac 
1 /*
2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24/**
25 * @test
26 * @bug 6425477
27 * @summary Better support for generation of high entropy random numbers
28 * @run main/othervm StrongSeedReader
29 */
30
31import java.io.*;
32import java.net.*;
33import java.security.SecureRandom;
34
35/**
36 * A simple test which takes into account knowledge about the underlying
37 * implementation. This may change if the implementations change.
38 *
39 * Create a new EGD file with known bytes, then set the EGD System property. The
40 * data read should be the same as what was written.
41 */
42public class StrongSeedReader {
43
44    public static void main(String[] args) throws Exception {
45        // Skip Windows, the SHA1PRNG uses CryptGenRandom.
46        if (System.getProperty("os.name", "unknown").startsWith("Windows")) {
47            return;
48        }
49
50        File file = null;
51        try {
52            file = new File(System.getProperty("java.io.tmpdir"),
53                    "StrongSeedReader.tmpdata");
54
55            // write a bunch of 0's to the file.
56            FileOutputStream fos = new FileOutputStream(file);
57            fos.write(new byte[2048]);
58
59            System.setProperty("java.security.egd", file.toURI().toString());
60            testSeed("NativePRNG");
61            testSeed("SHA1PRNG");
62            testSeed("DRBG");
63        } finally {
64            if (file != null) {
65                file.delete();
66            }
67        }
68    }
69
70    private static void testSeed(String alg) throws Exception {
71        System.out.println("Testing: " + alg);
72        SecureRandom sr = SecureRandom.getInstance(alg);
73        byte[] ba = sr.generateSeed(20);
74
75        // We should get back a bunch of zeros from the file.
76        for (byte b : ba) {
77            if (b != 0) {
78                throw new Exception("Byte != 0");
79            }
80        }
81    }
82}
83