package gnu.crypto.mac; // -*- mode: java; c-basic-offset: 3 -*-
// ----------------------------------------------------------------------------
// $Id: OMAC.java,v 1.2 2005/10/06 04:24:16 rsdio Exp $
//
// Copyright (C) 2004 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto 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, or (at your option)
// any later version.
//
// GNU Crypto 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 this program; see the file COPYING. If not, write to the
//
// Free Software Foundation Inc.,
// 51 Franklin Street, 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
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// 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.
// ---------------------------------------------------------------------------
import gnu.crypto.Registry;
import gnu.crypto.cipher.CipherFactory;
import gnu.crypto.cipher.IBlockCipher;
import gnu.crypto.mode.IMode;
import gnu.crypto.mode.ModeFactory;
import gnu.crypto.util.Util;
import java.security.InvalidKeyException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
/**
* <p>The One-Key CBC MAC, OMAC. This message authentication code is based on
* a block cipher in CBC mode.</p>
*
* <p>References:</p>
* <ol>
* <li>Tetsu Iwata and Kaoru Kurosawa, <i><a
* href="http://crypt.cis.ibaraki.ac.jp/omac/docs/omac.pdf">OMAC: One-Key CBC
* MAC</a></i>.</li>
* </ol>
*/
public class OMAC implements IMac {
// Constants and fields.
// ------------------------------------------------------------------------
private static final boolean DEBUG = false;
private static void debug(String msg) {
System.out.print(">>> OMAC: ");
System.out.println(msg);
}
private static final byte C1 = (byte) 0x87;
private static final byte C2 = 0x1b;
// Test key for OMAC-AES-128
private static final byte[] KEY0 = Util.toBytesFromString("2b7e151628aed2a6abf7158809cf4f3c");
// Test MAC for zero-length input.
private static final byte[] DIGEST0 = Util.toBytesFromString("bb1d6929e95937287fa37d129b756746");
private static Boolean valid;
private final IBlockCipher cipher;
private final String name;
private IMode mode;
private int blockSize;
private int outputSize;
private byte[] Lu, Lu2;
private byte[] M;
private byte[] Y;
private boolean init;
private int index;
// Constructor.
// ------------------------------------------------------------------------
public OMAC(IBlockCipher cipher) {
this.cipher = cipher;
this.name = "OMAC-" + cipher.name();
}
// Instance methods.
// ------------------------------------------------------------------------
public Object clone() {
return new OMAC(cipher);
}
public String name() {
return name;
}
public int macSize() {
return outputSize;
}
public void init(Map attrib) throws InvalidKeyException {
HashMap attrib2 = new HashMap();
attrib2.put(IBlockCipher.KEY_MATERIAL, attrib.get(MAC_KEY_MATERIAL));
cipher.reset();
cipher.init(attrib2);
blockSize = cipher.currentBlockSize();
Integer os = (Integer) attrib.get(TRUNCATED_SIZE);
if (os != null) {
outputSize = os.intValue();
if (outputSize < 0 || outputSize > blockSize) {
throw new IllegalArgumentException("truncated size out of range");
}
} else {
outputSize = blockSize;
}
byte[] L = new byte[blockSize];
cipher.encryptBlock(L, 0, L, 0);
if (DEBUG) {
debug("L = " + Util.toString(L).toLowerCase());
}
if (Lu != null) {
Arrays.fill(Lu, (byte) 0);
if (Lu.length != blockSize) {
Lu = new byte[blockSize];
}
} else {
Lu = new byte[blockSize];
}
if (Lu2 != null) {
Arrays.fill(Lu2, (byte) 0);
if (Lu2.length != blockSize) {
Lu2 = new byte[blockSize];
}
} else {
Lu2 = new byte[blockSize];
}
boolean msb = (L[0] & 0x80) != 0;
for (int i = 0; i < blockSize; i++) {
Lu[i] = (byte) (L[i] << 1 & 0xFF);
if (i+1 < blockSize) {
Lu[i] |= (byte) ((L[i + 1] & 0x80) >> 7);
}
}
if (msb) {
if (blockSize == 16) {
Lu[Lu.length-1] ^= C1;
} else if (blockSize == 8) {
Lu[Lu.length-1] ^= C2;
} else {
throw new IllegalArgumentException("unsupported cipher block size: "+blockSize);
}
}
if (DEBUG) {
debug("Lu = " + Util.toString(Lu).toLowerCase());
}
msb = (Lu[0] & 0x80) != 0;
for (int i = 0; i < blockSize; i++) {
Lu2[i] = (byte) (Lu[i] << 1 & 0xFF);
if (i+1 < blockSize) {
Lu2[i] |= (byte) ((Lu[i + 1] & 0x80) >> 7);
}
}
if (msb) {
if (blockSize == 16) {
Lu2[Lu2.length-1] ^= C1;
} else {
Lu2[Lu2.length-1] ^= C2;
}
}
if (DEBUG) {
debug("Lu2 = " + Util.toString(Lu2).toLowerCase());
}
if (M != null) {
Arrays.fill(M, (byte) 0);
if (M.length != blockSize) {
M = new byte[blockSize];
}
} else {
M = new byte[blockSize];
}
if (Y != null) {
Arrays.fill(Y, (byte) 0);
if (Y.length != blockSize) {
Y = new byte[blockSize];
}
} else {
Y = new byte[blockSize];
}
index = 0;
init = true;
}
public void update(byte b) {
if (!init) {
throw new IllegalStateException("not initialized");
}
if (index == M.length) {
process();
index = 0;
}
M[index++] = b;
}
public void update(byte[] buf, int off, int len) {
if (!init) {
throw new IllegalStateException("not initialized");
}
if (off < 0 || len < 0 || off + len > buf.length) {
throw new IndexOutOfBoundsException("size="+buf.length+"; off="+off+
"; len="+len);
}
for (int i = 0; i < len; ) {
if (index == blockSize) {
process();
index = 0;
}
int count = Math.min(blockSize - index, len - i);
System.arraycopy(buf, off+i, M, index, count);
index += count;
i += count;
}
}
public byte[] digest() {
byte[] b = new byte[outputSize];
digest(b, 0);
return b;
}
public void digest(byte[] out, int off) {
if (!init) {
throw new IllegalStateException("not initialized");
}
if (off < 0 || off+outputSize > out.length) {
throw new IndexOutOfBoundsException("size="+out.length+"; off="+off+
"; len="+outputSize);
}
byte[] T = new byte[blockSize];
byte[] L = Lu;
if (index < blockSize) {
M[index++] = (byte) 0x80;
while (index < blockSize) {
M[index++] = 0;
}
L = Lu2;
}
for (int i = 0; i < blockSize; i++) {
T[i] = (byte) (M[i] ^ Y[i] ^ L[i]);
}
cipher.encryptBlock(T, 0, T, 0);
System.arraycopy(T, 0, out, off, outputSize);
reset();
}
public void reset() {
index = 0;
if (Y != null) {
Arrays.fill(Y, (byte) 0);
}
if (M != null) {
Arrays.fill(M, (byte) 0);
}
}
public boolean selfTest() {
OMAC mac = new OMAC(CipherFactory.getInstance(Registry.AES_CIPHER));
mac.reset();
Map attr = new HashMap();
attr.put(MAC_KEY_MATERIAL, KEY0);
byte[] digest = null;
try {
mac.init(attr);
digest = mac.digest();
} catch (Exception x) {
return false;
}
if (digest == null) {
return false;
}
return Arrays.equals(DIGEST0, digest);
}
// Own methods.
// ------------------------------------------------------------------------
private void process() {
for (int i = 0; i < blockSize; i++) {
M[i] = (byte) (M[i] ^ Y[i]);
}
cipher.encryptBlock(M, 0, Y, 0);
}
}