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