1/*
2 * Copyright (c) 2017, 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 8183591
27 * @summary Test decoding of DER length fields containing Integer.MAX_VALUE
28 * @run main TestMaxLengthDER
29 */
30
31import java.io.*;
32import java.math.*;
33import java.security.*;
34import java.security.spec.*;
35
36public class TestMaxLengthDER {
37
38    public static void main(String[] args) throws Exception {
39
40        String message = "Message";
41        Signature sig = Signature.getInstance("SHA256withDSA");
42        KeyPairGenerator kpg = KeyPairGenerator.getInstance("DSA");
43        SecureRandom rnd = new SecureRandom();
44        rnd.setSeed(1);
45        kpg.initialize(2048, rnd);
46        KeyPair kp = kpg.generateKeyPair();
47        sig.initSign(kp.getPrivate());
48        sig.update(message.getBytes());
49        byte[] sigData = sig.sign();
50
51        // Set the length of the second integer to Integer.MAX_VALUE
52        // First copy all the signature data to the correct location
53        int lengthPos = sigData[3] + 5;
54        byte[] modifiedSigData = new byte[sigData.length + 4];
55        System.arraycopy(sigData, 0, modifiedSigData, 0, lengthPos);
56        System.arraycopy(sigData, lengthPos + 1, modifiedSigData,
57            lengthPos + 5, sigData.length - (lengthPos + 1));
58
59        // Increase the length (in bytes) of the sequence to account for
60        // the larger length field
61        modifiedSigData[1] += 4;
62
63        // Modify the length field
64        modifiedSigData[lengthPos] = (byte) 0x84;
65        modifiedSigData[lengthPos + 1] = (byte) 0x7F;
66        modifiedSigData[lengthPos + 2] = (byte) 0xFF;
67        modifiedSigData[lengthPos + 3] = (byte) 0xFF;
68        modifiedSigData[lengthPos + 4] = (byte) 0xFF;
69
70        sig.initVerify(kp.getPublic());
71        sig.update(message.getBytes());
72
73        try {
74            sig.verify(modifiedSigData);
75            throw new RuntimeException("No exception on misencoded signature");
76        } catch (SignatureException ex) {
77            if (ex.getCause() instanceof EOFException) {
78                // this is expected
79            } else {
80                throw ex;
81            }
82        }
83    }
84}
85