| /* |
| * Copyright (c) 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. |
| */ |
| /* |
| * (C) Copyright IBM Corp. 2013 |
| */ |
| |
| package com.sun.crypto.provider; |
| |
| import java.util.Arrays; |
| import java.security.*; |
| import static com.sun.crypto.provider.AESConstants.AES_BLOCK_SIZE; |
| |
| /** |
| * This class represents the GHASH function defined in NIST 800-38D |
| * under section 6.4. It needs to be constructed w/ a hash subkey, i.e. |
| * block H. Given input of 128-bit blocks, it will process and output |
| * a 128-bit block. |
| * |
| * <p>This function is used in the implementation of GCM mode. |
| * |
| * @since 1.8 |
| */ |
| final class GHASH { |
| |
| private static final byte P128 = (byte) 0xe1; //reduction polynomial |
| |
| private static boolean getBit(byte[] b, int pos) { |
| int p = pos / 8; |
| pos %= 8; |
| int i = (b[p] >>> (7 - pos)) & 1; |
| return i != 0; |
| } |
| |
| private static void shift(byte[] b) { |
| byte temp, temp2; |
| temp2 = 0; |
| for (int i = 0; i < b.length; i++) { |
| temp = (byte) ((b[i] & 0x01) << 7); |
| b[i] = (byte) ((b[i] & 0xff) >>> 1); |
| b[i] = (byte) (b[i] | temp2); |
| temp2 = temp; |
| } |
| } |
| |
| // Given block X and Y, returns the muliplication of X * Y |
| private static byte[] blockMult(byte[] x, byte[] y) { |
| if (x.length != AES_BLOCK_SIZE || y.length != AES_BLOCK_SIZE) { |
| throw new RuntimeException("illegal input sizes"); |
| } |
| byte[] z = new byte[AES_BLOCK_SIZE]; |
| byte[] v = y.clone(); |
| // calculate Z1-Z127 and V1-V127 |
| for (int i = 0; i < 127; i++) { |
| // Zi+1 = Zi if bit i of x is 0 |
| if (getBit(x, i)) { |
| for (int n = 0; n < z.length; n++) { |
| z[n] ^= v[n]; |
| } |
| } |
| boolean lastBitOfV = getBit(v, 127); |
| shift(v); |
| if (lastBitOfV) v[0] ^= P128; |
| } |
| // calculate Z128 |
| if (getBit(x, 127)) { |
| for (int n = 0; n < z.length; n++) { |
| z[n] ^= v[n]; |
| } |
| } |
| return z; |
| } |
| |
| // hash subkey H; should not change after the object has been constructed |
| private final byte[] subkeyH; |
| |
| // buffer for storing hash |
| private byte[] state; |
| |
| // variables for save/restore calls |
| private byte[] stateSave = null; |
| |
| /** |
| * Initializes the cipher in the specified mode with the given key |
| * and iv. |
| * |
| * @param subkeyH the hash subkey |
| * |
| * @exception ProviderException if the given key is inappropriate for |
| * initializing this digest |
| */ |
| GHASH(byte[] subkeyH) throws ProviderException { |
| if ((subkeyH == null) || subkeyH.length != AES_BLOCK_SIZE) { |
| throw new ProviderException("Internal error"); |
| } |
| this.subkeyH = subkeyH; |
| this.state = new byte[AES_BLOCK_SIZE]; |
| } |
| |
| /** |
| * Resets the GHASH object to its original state, i.e. blank w/ |
| * the same subkey H. Used after digest() is called and to re-use |
| * this object for different data w/ the same H. |
| */ |
| void reset() { |
| Arrays.fill(state, (byte) 0); |
| } |
| |
| /** |
| * Save the current snapshot of this GHASH object. |
| */ |
| void save() { |
| stateSave = state.clone(); |
| } |
| |
| /** |
| * Restores this object using the saved snapshot. |
| */ |
| void restore() { |
| state = stateSave; |
| } |
| |
| private void processBlock(byte[] data, int ofs) { |
| if (data.length - ofs < AES_BLOCK_SIZE) { |
| throw new RuntimeException("need complete block"); |
| } |
| for (int n = 0; n < state.length; n++) { |
| state[n] ^= data[ofs + n]; |
| } |
| state = blockMult(state, subkeyH); |
| } |
| |
| void update(byte[] in) { |
| update(in, 0, in.length); |
| } |
| |
| void update(byte[] in, int inOfs, int inLen) { |
| if (inLen - inOfs > in.length) { |
| throw new RuntimeException("input length out of bound"); |
| } |
| if (inLen % AES_BLOCK_SIZE != 0) { |
| throw new RuntimeException("input length unsupported"); |
| } |
| |
| for (int i = inOfs; i < (inOfs + inLen); i += AES_BLOCK_SIZE) { |
| processBlock(in, i); |
| } |
| } |
| |
| byte[] digest() { |
| try { |
| return state.clone(); |
| } finally { |
| reset(); |
| } |
| } |
| } |