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 
  31 import java.io.*;
  32 import java.math.*;
  33 import java.security.*;
  34 import java.security.spec.*;
  35 
  36 public 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 }