| /* |
| * Copyright (c) 1997, 2013, 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 java.security; |
| |
| import java.nio.ByteBuffer; |
| |
| import sun.security.jca.JCAUtil; |
| |
| /** |
| * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>) |
| * for the {@code MessageDigest} class, which provides the functionality |
| * of a message digest algorithm, such as MD5 or SHA. Message digests are |
| * secure one-way hash functions that take arbitrary-sized data and output a |
| * fixed-length hash value. |
| * |
| * <p> All the abstract methods in this class must be implemented by a |
| * cryptographic service provider who wishes to supply the implementation |
| * of a particular message digest algorithm. |
| * |
| * <p> Implementations are free to implement the Cloneable interface. |
| * |
| * @author Benjamin Renaud |
| * |
| * |
| * @see MessageDigest |
| */ |
| |
| public abstract class MessageDigestSpi { |
| |
| // for re-use in engineUpdate(ByteBuffer input) |
| private byte[] tempArray; |
| |
| /** |
| * Returns the digest length in bytes. |
| * |
| * <p>This concrete method has been added to this previously-defined |
| * abstract class. (For backwards compatibility, it cannot be abstract.) |
| * |
| * <p>The default behavior is to return 0. |
| * |
| * <p>This method may be overridden by a provider to return the digest |
| * length. |
| * |
| * @return the digest length in bytes. |
| * |
| * @since 1.2 |
| */ |
| protected int engineGetDigestLength() { |
| return 0; |
| } |
| |
| /** |
| * Updates the digest using the specified byte. |
| * |
| * @param input the byte to use for the update. |
| */ |
| protected abstract void engineUpdate(byte input); |
| |
| /** |
| * Updates the digest using the specified array of bytes, |
| * starting at the specified offset. |
| * |
| * @param input the array of bytes to use for the update. |
| * |
| * @param offset the offset to start from in the array of bytes. |
| * |
| * @param len the number of bytes to use, starting at |
| * {@code offset}. |
| */ |
| protected abstract void engineUpdate(byte[] input, int offset, int len); |
| |
| /** |
| * Update the digest using the specified ByteBuffer. The digest is |
| * updated using the {@code input.remaining()} bytes starting |
| * at {@code input.position()}. |
| * Upon return, the buffer's position will be equal to its limit; |
| * its limit will not have changed. |
| * |
| * @param input the ByteBuffer |
| * @since 1.5 |
| */ |
| protected void engineUpdate(ByteBuffer input) { |
| if (input.hasRemaining() == false) { |
| return; |
| } |
| if (input.hasArray()) { |
| byte[] b = input.array(); |
| int ofs = input.arrayOffset(); |
| int pos = input.position(); |
| int lim = input.limit(); |
| engineUpdate(b, ofs + pos, lim - pos); |
| input.position(lim); |
| } else { |
| int len = input.remaining(); |
| int n = JCAUtil.getTempArraySize(len); |
| if ((tempArray == null) || (n > tempArray.length)) { |
| tempArray = new byte[n]; |
| } |
| while (len > 0) { |
| int chunk = Math.min(len, tempArray.length); |
| input.get(tempArray, 0, chunk); |
| engineUpdate(tempArray, 0, chunk); |
| len -= chunk; |
| } |
| } |
| } |
| |
| /** |
| * Completes the hash computation by performing final |
| * operations such as padding. Once {@code engineDigest} has |
| * been called, the engine should be reset (see |
| * {@link #engineReset() engineReset}). |
| * Resetting is the responsibility of the |
| * engine implementor. |
| * |
| * @return the array of bytes for the resulting hash value. |
| */ |
| protected abstract byte[] engineDigest(); |
| |
| /** |
| * Completes the hash computation by performing final |
| * operations such as padding. Once {@code engineDigest} has |
| * been called, the engine should be reset (see |
| * {@link #engineReset() engineReset}). |
| * Resetting is the responsibility of the |
| * engine implementor. |
| * |
| * This method should be abstract, but we leave it concrete for |
| * binary compatibility. Knowledgeable providers should override this |
| * method. |
| * |
| * @param buf the output buffer in which to store the digest |
| * |
| * @param offset offset to start from in the output buffer |
| * |
| * @param len number of bytes within buf allotted for the digest. |
| * Both this default implementation and the SUN provider do not |
| * return partial digests. The presence of this parameter is solely |
| * for consistency in our API's. If the value of this parameter is less |
| * than the actual digest length, the method will throw a DigestException. |
| * This parameter is ignored if its value is greater than or equal to |
| * the actual digest length. |
| * |
| * @return the length of the digest stored in the output buffer. |
| * |
| * @exception DigestException if an error occurs. |
| * |
| * @since 1.2 |
| */ |
| protected int engineDigest(byte[] buf, int offset, int len) |
| throws DigestException { |
| |
| byte[] digest = engineDigest(); |
| if (len < digest.length) |
| throw new DigestException("partial digests not returned"); |
| if (buf.length - offset < digest.length) |
| throw new DigestException("insufficient space in the output " |
| + "buffer to store the digest"); |
| System.arraycopy(digest, 0, buf, offset, digest.length); |
| return digest.length; |
| } |
| |
| /** |
| * Resets the digest for further use. |
| */ |
| protected abstract void engineReset(); |
| |
| /** |
| * Returns a clone if the implementation is cloneable. |
| * |
| * @return a clone if the implementation is cloneable. |
| * |
| * @exception CloneNotSupportedException if this is called on an |
| * implementation that does not support {@code Cloneable}. |
| */ |
| public Object clone() throws CloneNotSupportedException { |
| if (this instanceof Cloneable) { |
| return super.clone(); |
| } else { |
| throw new CloneNotSupportedException(); |
| } |
| } |
| } |