/*
 * Copyright (c) 2003, 2014, 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.provider;

import java.security.MessageDigestSpi;
import java.security.DigestException;
import java.security.ProviderException;
import java.util.Arrays;
import java.util.Objects;

Common base message digest implementation for the Sun provider. It implements all the JCA methods as suitable for a Java message digest implementation of an algorithm based on a compression function (as all commonly used algorithms are). The individual digest subclasses only need to implement the following methods: . abstract void implCompress(byte[] b, int ofs); . abstract void implDigest(byte[] out, int ofs); . abstract void implReset(); See the inline documentation for details.
Author: Andreas Sterbenz
Since: 1.5
/** * Common base message digest implementation for the Sun provider. * It implements all the JCA methods as suitable for a Java message digest * implementation of an algorithm based on a compression function (as all * commonly used algorithms are). The individual digest subclasses only need to * implement the following methods: * * . abstract void implCompress(byte[] b, int ofs); * . abstract void implDigest(byte[] out, int ofs); * . abstract void implReset(); * * See the inline documentation for details. * * @since 1.5 * @author Andreas Sterbenz */
abstract class DigestBase extends MessageDigestSpi implements Cloneable { // one element byte array, temporary storage for update(byte) private byte[] oneByte; // algorithm name to use in the exception message private final String algorithm; // length of the message digest in bytes private final int digestLength; // size of the input to the compression function in bytes private final int blockSize; // buffer to store partial blocks, blockSize bytes large // Subclasses should not access this array directly except possibly in their // implDigest() method. See MD5.java as an example. byte[] buffer; // offset into buffer private int bufOfs; // number of bytes processed so far. subclasses should not modify // this value. // also used as a flag to indicate reset status // -1: need to call engineReset() before next call to update() // 0: is already reset long bytesProcessed;
Main constructor.
/** * Main constructor. */
DigestBase(String algorithm, int digestLength, int blockSize) { super(); this.algorithm = algorithm; this.digestLength = digestLength; this.blockSize = blockSize; buffer = new byte[blockSize]; } // return digest length. See JCA doc. protected final int engineGetDigestLength() { return digestLength; } // single byte update. See JCA doc. protected final void engineUpdate(byte b) { if (oneByte == null) { oneByte = new byte[1]; } oneByte[0] = b; engineUpdate(oneByte, 0, 1); } // array update. See JCA doc. protected final void engineUpdate(byte[] b, int ofs, int len) { if (len == 0) { return; } if ((ofs < 0) || (len < 0) || (ofs > b.length - len)) { throw new ArrayIndexOutOfBoundsException(); } if (bytesProcessed < 0) { engineReset(); } bytesProcessed += len; // if buffer is not empty, we need to fill it before proceeding if (bufOfs != 0) { int n = Math.min(len, blockSize - bufOfs); System.arraycopy(b, ofs, buffer, bufOfs, n); bufOfs += n; ofs += n; len -= n; if (bufOfs >= blockSize) { // compress completed block now implCompress(buffer, 0); bufOfs = 0; } } // compress complete blocks if (len >= blockSize) { int limit = ofs + len; ofs = implCompressMultiBlock(b, ofs, limit - blockSize); len = limit - ofs; } // copy remainder to buffer if (len > 0) { System.arraycopy(b, ofs, buffer, 0, len); bufOfs = len; } } // compress complete blocks private int implCompressMultiBlock(byte[] b, int ofs, int limit) { implCompressMultiBlockCheck(b, ofs, limit); return implCompressMultiBlock0(b, ofs, limit); } private int implCompressMultiBlock0(byte[] b, int ofs, int limit) { for (; ofs <= limit; ofs += blockSize) { implCompress(b, ofs); } return ofs; } private void implCompressMultiBlockCheck(byte[] b, int ofs, int limit) { if (limit < 0) { return; // not an error because implCompressMultiBlockImpl won't execute if limit < 0 // and an exception is thrown if ofs < 0. } Objects.requireNonNull(b); if (ofs < 0 || ofs >= b.length) { throw new ArrayIndexOutOfBoundsException(ofs); } int endIndex = (limit / blockSize) * blockSize + blockSize - 1; if (endIndex >= b.length) { throw new ArrayIndexOutOfBoundsException(endIndex); } } // reset this object. See JCA doc. protected final void engineReset() { if (bytesProcessed == 0) { // already reset, ignore return; } implReset(); bufOfs = 0; bytesProcessed = 0; Arrays.fill(buffer, (byte) 0x00); } // return the digest. See JCA doc. protected final byte[] engineDigest() { byte[] b = new byte[digestLength]; try { engineDigest(b, 0, b.length); } catch (DigestException e) { throw (ProviderException) new ProviderException("Internal error").initCause(e); } return b; } // return the digest in the specified array. See JCA doc. protected final int engineDigest(byte[] out, int ofs, int len) throws DigestException { if (len < digestLength) { throw new DigestException("Length must be at least " + digestLength + " for " + algorithm + "digests"); } if ((ofs < 0) || (len < 0) || (ofs > out.length - len)) { throw new DigestException("Buffer too short to store digest"); } if (bytesProcessed < 0) { engineReset(); } implDigest(out, ofs); bytesProcessed = -1; return digestLength; }
Core compression function. Processes blockSize bytes at a time and updates the state of this object.
/** * Core compression function. Processes blockSize bytes at a time * and updates the state of this object. */
abstract void implCompress(byte[] b, int ofs);
Return the digest. Subclasses do not need to reset() themselves, DigestBase calls implReset() when necessary.
/** * Return the digest. Subclasses do not need to reset() themselves, * DigestBase calls implReset() when necessary. */
abstract void implDigest(byte[] out, int ofs);
Reset subclass specific state to their initial values. DigestBase calls this method when necessary.
/** * Reset subclass specific state to their initial values. DigestBase * calls this method when necessary. */
abstract void implReset(); public Object clone() throws CloneNotSupportedException { DigestBase copy = (DigestBase) super.clone(); copy.buffer = copy.buffer.clone(); return copy; } // padding used for the MD5, and SHA-* message digests static final byte[] padding; static { // we need 128 byte padding for SHA-384/512 // and an additional 8 bytes for the high 8 bytes of the 16 // byte bit counter in SHA-384/512 padding = new byte[136]; padding[0] = (byte)0x80; } }