Back to index...

	/*
	* Copyright (c) 2013, 2015, 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 state[0], state[1] by subkeyH[0], subkeyH[1].
	private static void blockMult(long[] st, long[] subH) {
	long Z0 = 0;
	long Z1 = 0;
	long V0 = subH[0];
	long V1 = subH[1];
	long X;

	// Separate loops for processing state[0] and state[1].
	X = st[0];
	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 = st[1];
	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.
	st[0] = Z0;
	st[1] = Z1;

	}

	/* subkeyH and state are stored in long[] for GHASH intrinsic use */

	// hash subkey H; should not change after the object has been constructed
	private final long[] subkeyH;

	// buffer for storing hash
	private final long[] state;

	// 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");
	}
	state = new long[2];
	this.subkeyH = new long[2];
	this.subkeyH[0] = getLong(subkeyH, 0);
	this.subkeyH[1] = 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() {
	state[0] = 0;
	state[1] = 0;
	}

	/**
	* Save the current snapshot of this GHASH object.
	*/
	void save() {
	stateSave0 = state[0];
	stateSave1 = state[1];
	}

	/**
	* Restores this object using the saved snapshot.
	*/
	void restore() {
	state[0] = stateSave0;
	state[1] = stateSave1;
	}

	private static void processBlock(byte[] data, int ofs, long[] st, long[] subH) {
	st[0] ^= getLong(data, ofs);
	st[1] ^= getLong(data, ofs + 8);
	blockMult(st, subH);
	}

	void update(byte[] in) {
	update(in, 0, in.length);
	}

	void update(byte[] in, int inOfs, int inLen) {
	if (inLen == 0) {
	return;
	}
	ghashRangeCheck(in, inOfs, inLen, state, subkeyH);
	processBlocks(in, inOfs, inLen/AES_BLOCK_SIZE, state, subkeyH);
	}

	private static void ghashRangeCheck(byte[] in, int inOfs, int inLen, long[] st, long[] subH) {
	if (inLen < 0) {
	throw new RuntimeException("invalid input length: " + inLen);
	}
	if (inOfs < 0) {
	throw new RuntimeException("invalid offset: " + inOfs);
	}
	if (inLen > in.length - inOfs) {
	throw new RuntimeException("input length out of bound: " +
	inLen + " > " + (in.length - inOfs));
	}
	if (inLen % AES_BLOCK_SIZE != 0) {
	throw new RuntimeException("input length/block size mismatch: " +
	inLen);
	}

	// These two checks are for C2 checking
	if (st.length != 2) {
	throw new RuntimeException("internal state has invalid length: " +
	st.length);
	}
	if (subH.length != 2) {
	throw new RuntimeException("internal subkeyH has invalid length: " +
	subH.length);
	}
	}
	/*
	* This is an intrinsified method. The method's argument list must match
	* the hotspot signature. This method and methods called by it, cannot
	* throw exceptions or allocate arrays as it will breaking intrinsics
	*/
	private static void processBlocks(byte[] data, int inOfs, int blocks, long[] st, long[] subH) {
	int offset = inOfs;
	while (blocks > 0) {
	processBlock(data, offset, st, subH);
	blocks--;
	offset += AES_BLOCK_SIZE;
	}
	}

	byte[] digest() {
	byte[] result = new byte[AES_BLOCK_SIZE];
	putLong(result, 0, state[0]);
	putLong(result, 8, state[1]);
	reset();
	return result;
	}
	}

Back to index...