| /* |
| * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved. |
| * Copyright (c) 2015 Red Hat, Inc. |
| * 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.security.ProviderException; |
| |
| /** |
| * 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 long getLong(byte[] buffer, int offset) { |
| long result = 0; |
| int end = offset + 8; |
| for (int i = offset; i < end; ++i) { |
| result = (result << 8) + (buffer[i] & 0xFF); |
| } |
| return result; |
| } |
| |
| private static void putLong(byte[] buffer, int offset, long value) { |
| int end = offset + 8; |
| for (int i = end - 1; i >= offset; --i) { |
| buffer[i] = (byte) value; |
| value >>= 8; |
| } |
| } |
| |
| private static final int AES_BLOCK_SIZE = 16; |
| |
| // Multiplies state0, state1 by V0, V1. |
| private void blockMult(long V0, long V1) { |
| long Z0 = 0; |
| long Z1 = 0; |
| long X; |
| |
| // Separate loops for processing state0 and state1. |
| X = state0; |
| for (int i = 0; i < 64; i++) { |
| // Zi+1 = Zi if bit i of x is 0 |
| long mask = X >> 63; |
| Z0 ^= V0 & mask; |
| Z1 ^= V1 & mask; |
| |
| // Save mask for conditional reduction below. |
| mask = (V1 << 63) >> 63; |
| |
| // V = rightshift(V) |
| long carry = V0 & 1; |
| V0 = V0 >>> 1; |
| V1 = (V1 >>> 1) | (carry << 63); |
| |
| // Conditional reduction modulo P128. |
| V0 ^= 0xe100000000000000L & mask; |
| X <<= 1; |
| } |
| |
| X = state1; |
| for (int i = 64; i < 127; i++) { |
| // Zi+1 = Zi if bit i of x is 0 |
| long mask = X >> 63; |
| Z0 ^= V0 & mask; |
| Z1 ^= V1 & mask; |
| |
| // Save mask for conditional reduction below. |
| mask = (V1 << 63) >> 63; |
| |
| // V = rightshift(V) |
| long carry = V0 & 1; |
| V0 = V0 >>> 1; |
| V1 = (V1 >>> 1) | (carry << 63); |
| |
| // Conditional reduction. |
| V0 ^= 0xe100000000000000L & mask; |
| X <<= 1; |
| } |
| |
| // calculate Z128 |
| long mask = X >> 63; |
| Z0 ^= V0 & mask; |
| Z1 ^= V1 & mask; |
| |
| // Save result. |
| state0 = Z0; |
| state1 = Z1; |
| } |
| |
| // hash subkey H; should not change after the object has been constructed |
| private final long subkeyH0, subkeyH1; |
| |
| // buffer for storing hash |
| private long state0, state1; |
| |
| // variables for save/restore calls |
| private long stateSave0, stateSave1; |
| |
| /** |
| * 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.subkeyH0 = getLong(subkeyH, 0); |
| this.subkeyH1 = getLong(subkeyH, 8); |
| } |
| |
| /** |
| * 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() { |
| state0 = 0; |
| state1 = 0; |
| } |
| |
| /** |
| * Save the current snapshot of this GHASH object. |
| */ |
| void save() { |
| stateSave0 = state0; |
| stateSave1 = state1; |
| } |
| |
| /** |
| * Restores this object using the saved snapshot. |
| */ |
| void restore() { |
| state0 = stateSave0; |
| state1 = stateSave1; |
| } |
| |
| private void processBlock(byte[] data, int ofs) { |
| if (data.length - ofs < AES_BLOCK_SIZE) { |
| throw new RuntimeException("need complete block"); |
| } |
| state0 ^= getLong(data, ofs); |
| state1 ^= getLong(data, ofs + 8); |
| blockMult(subkeyH0, subkeyH1); |
| } |
| |
| 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() { |
| byte[] result = new byte[AES_BLOCK_SIZE]; |
| putLong(result, 0, state0); |
| putLong(result, 8, state1); |
| reset(); |
| return result; |
| } |
| } |