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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/java/security/hash/BaseHash.java | |
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Diffstat (limited to 'libjava/classpath/gnu/java/security/hash/BaseHash.java')
-rw-r--r-- | libjava/classpath/gnu/java/security/hash/BaseHash.java | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/security/hash/BaseHash.java b/libjava/classpath/gnu/java/security/hash/BaseHash.java new file mode 100644 index 000000000..bab930f28 --- /dev/null +++ b/libjava/classpath/gnu/java/security/hash/BaseHash.java @@ -0,0 +1,183 @@ +/* BaseHash.java -- + Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc. + +This file is a part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at +your option) any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 +USA + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.java.security.hash; + +/** + * A base abstract class to facilitate hash implementations. + */ +public abstract class BaseHash + implements IMessageDigest +{ + /** The canonical name prefix of the hash. */ + protected String name; + + /** The hash (output) size in bytes. */ + protected int hashSize; + + /** The hash (inner) block size in bytes. */ + protected int blockSize; + + /** Number of bytes processed so far. */ + protected long count; + + /** Temporary input buffer. */ + protected byte[] buffer; + + /** + * Trivial constructor for use by concrete subclasses. + * + * @param name the canonical name prefix of this instance. + * @param hashSize the block size of the output in bytes. + * @param blockSize the block size of the internal transform. + */ + protected BaseHash(String name, int hashSize, int blockSize) + { + super(); + + this.name = name; + this.hashSize = hashSize; + this.blockSize = blockSize; + this.buffer = new byte[blockSize]; + + resetContext(); + } + + public String name() + { + return name; + } + + public int hashSize() + { + return hashSize; + } + + public int blockSize() + { + return blockSize; + } + + public void update(byte b) + { + // compute number of bytes still unhashed; ie. present in buffer + int i = (int) (count % blockSize); + count++; + buffer[i] = b; + if (i == (blockSize - 1)) + transform(buffer, 0); + } + + public void update(byte[] b) + { + update(b, 0, b.length); + } + + public void update(byte[] b, int offset, int len) + { + int n = (int) (count % blockSize); + count += len; + int partLen = blockSize - n; + int i = 0; + + if (len >= partLen) + { + System.arraycopy(b, offset, buffer, n, partLen); + transform(buffer, 0); + for (i = partLen; i + blockSize - 1 < len; i += blockSize) + transform(b, offset + i); + + n = 0; + } + + if (i < len) + System.arraycopy(b, offset + i, buffer, n, len - i); + } + + public byte[] digest() + { + byte[] tail = padBuffer(); // pad remaining bytes in buffer + update(tail, 0, tail.length); // last transform of a message + byte[] result = getResult(); // make a result out of context + + reset(); // reset this instance for future re-use + + return result; + } + + public void reset() + { // reset this instance for future re-use + count = 0L; + for (int i = 0; i < blockSize;) + buffer[i++] = 0; + + resetContext(); + } + + public abstract Object clone(); + + public abstract boolean selfTest(); + + /** + * Returns the byte array to use as padding before completing a hash + * operation. + * + * @return the bytes to pad the remaining bytes in the buffer before + * completing a hash operation. + */ + protected abstract byte[] padBuffer(); + + /** + * Constructs the result from the contents of the current context. + * + * @return the output of the completed hash operation. + */ + protected abstract byte[] getResult(); + + /** Resets the instance for future re-use. */ + protected abstract void resetContext(); + + /** + * The block digest transformation per se. + * + * @param in the <i>blockSize</i> long block, as an array of bytes to digest. + * @param offset the index where the data to digest is located within the + * input buffer. + */ + protected abstract void transform(byte[] in, int offset); +} |