| /* |
| * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package sun.security.util; |
| |
| /** |
| * A time-instance comparison of two byte arrays. |
| */ |
| public class ByteArrays { |
| // See the MessageDigest.isEqual(byte[] digesta, byte[] digestb) |
| // implementation. This is a potential enhancement of the |
| // MessageDigest class. |
| public static boolean isEqual(byte[] a, int aFromIndex, int aToIndex, |
| byte[] b, int bFromIndex, int bToIndex) { |
| if (a == b) { |
| return true; |
| } |
| |
| if (a == null || b == null) { |
| return false; |
| } |
| |
| if (a.length == 0) { |
| return b.length == 0; |
| } |
| |
| int lenA = aToIndex - aFromIndex; |
| int lenB = bToIndex - bFromIndex; |
| |
| if (lenB == 0) { |
| return lenA == 0; |
| } |
| |
| int result = 0; |
| result |= lenA - lenB; |
| |
| // time-constant comparison |
| for (int indexA = 0; indexA < lenA; indexA++) { |
| int indexB = ((indexA - lenB) >>> 31) * indexA; |
| result |= a[aFromIndex + indexA] ^ b[bFromIndex + indexB]; |
| } |
| |
| return result == 0; |
| } |
| } |
