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