1 /*
2 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2015 Red Hat, Inc.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation. Oracle designates this
9 * particular file as subject to the "Classpath" exception as provided
10 * by Oracle in the LICENSE file that accompanied this code.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
23 * or visit www.oracle.com if you need additional information or have any
24 * questions.
25 */
26 /*
27 * (C) Copyright IBM Corp. 2013
28 */
29
30 package com.sun.crypto.provider;
31
32 import java.security.ProviderException;
33
34 import jdk.internal.HotSpotIntrinsicCandidate;
35
36 /**
37 * This class represents the GHASH function defined in NIST 800-38D
38 * under section 6.4. It needs to be constructed w/ a hash subkey, i.e.
39 * block H. Given input of 128-bit blocks, it will process and output
40 * a 128-bit block.
41 *
42 * <p>This function is used in the implementation of GCM mode.
43 *
44 * @since 1.8
45 */
46 final class GHASH {
47
48 private static long getLong(byte[] buffer, int offset) {
49 long result = 0;
50 int end = offset + 8;
51 for (int i = offset; i < end; ++i) {
52 result = (result << 8) + (buffer[i] & 0xFF);
53 }
54 return result;
55 }
56
57 private static void putLong(byte[] buffer, int offset, long value) {
58 int end = offset + 8;
59 for (int i = end - 1; i >= offset; --i) {
60 buffer[i] = (byte) value;
61 value >>= 8;
62 }
63 }
64
65 private static final int AES_BLOCK_SIZE = 16;
66
67 // Multiplies state[0], state[1] by subkeyH[0], subkeyH[1].
68 private static void blockMult(long[] st, long[] subH) {
69 long Z0 = 0;
70 long Z1 = 0;
71 long V0 = subH[0];
72 long V1 = subH[1];
73 long X;
74
75 // Separate loops for processing state[0] and state[1].
76 X = st[0];
77 for (int i = 0; i < 64; i++) {
78 // Zi+1 = Zi if bit i of x is 0
79 long mask = X >> 63;
80 Z0 ^= V0 & mask;
81 Z1 ^= V1 & mask;
82
83 // Save mask for conditional reduction below.
84 mask = (V1 << 63) >> 63;
85
86 // V = rightshift(V)
87 long carry = V0 & 1;
88 V0 = V0 >>> 1;
89 V1 = (V1 >>> 1) | (carry << 63);
90
91 // Conditional reduction modulo P128.
92 V0 ^= 0xe100000000000000L & mask;
93 X <<= 1;
94 }
95
96 X = st[1];
97 for (int i = 64; i < 127; i++) {
98 // Zi+1 = Zi if bit i of x is 0
99 long mask = X >> 63;
100 Z0 ^= V0 & mask;
101 Z1 ^= V1 & mask;
102
103 // Save mask for conditional reduction below.
104 mask = (V1 << 63) >> 63;
105
106 // V = rightshift(V)
107 long carry = V0 & 1;
108 V0 = V0 >>> 1;
109 V1 = (V1 >>> 1) | (carry << 63);
110
111 // Conditional reduction.
112 V0 ^= 0xe100000000000000L & mask;
113 X <<= 1;
114 }
115
116 // calculate Z128
117 long mask = X >> 63;
118 Z0 ^= V0 & mask;
119 Z1 ^= V1 & mask;
120
121 // Save result.
122 st[0] = Z0;
123 st[1] = Z1;
124
125 }
126
127 /* subkeyH and state are stored in long[] for GHASH intrinsic use */
128
129 // hash subkey H; should not change after the object has been constructed
130 private final long[] subkeyH;
131
132 // buffer for storing hash
133 private final long[] state;
134
135 // variables for save/restore calls
136 private long stateSave0, stateSave1;
137
138 /**
139 * Initializes the cipher in the specified mode with the given key
140 * and iv.
141 *
142 * @param subkeyH the hash subkey
143 *
144 * @exception ProviderException if the given key is inappropriate for
145 * initializing this digest
146 */
147 GHASH(byte[] subkeyH) throws ProviderException {
148 if ((subkeyH == null) || subkeyH.length != AES_BLOCK_SIZE) {
149 throw new ProviderException("Internal error");
150 }
151 state = new long[2];
152 this.subkeyH = new long[2];
153 this.subkeyH[0] = getLong(subkeyH, 0);
154 this.subkeyH[1] = getLong(subkeyH, 8);
155 }
156
157 /**
158 * Resets the GHASH object to its original state, i.e. blank w/
159 * the same subkey H. Used after digest() is called and to re-use
160 * this object for different data w/ the same H.
161 */
162 void reset() {
163 state[0] = 0;
164 state[1] = 0;
165 }
166
167 /**
168 * Save the current snapshot of this GHASH object.
169 */
170 void save() {
171 stateSave0 = state[0];
172 stateSave1 = state[1];
173 }
174
175 /**
176 * Restores this object using the saved snapshot.
177 */
178 void restore() {
179 state[0] = stateSave0;
180 state[1] = stateSave1;
181 }
182
183 private static void processBlock(byte[] data, int ofs, long[] st, long[] subH) {
184 st[0] ^= getLong(data, ofs);
185 st[1] ^= getLong(data, ofs + 8);
186 blockMult(st, subH);
187 }
188
189 void update(byte[] in) {
190 update(in, 0, in.length);
191 }
192
193 void update(byte[] in, int inOfs, int inLen) {
194 if (inLen == 0) {
195 return;
196 }
197 ghashRangeCheck(in, inOfs, inLen, state, subkeyH);
198 processBlocks(in, inOfs, inLen/AES_BLOCK_SIZE, state, subkeyH);
199 }
200
201 private static void ghashRangeCheck(byte[] in, int inOfs, int inLen, long[] st, long[] subH) {
202 if (inLen < 0) {
203 throw new RuntimeException("invalid input length: " + inLen);
204 }
205 if (inOfs < 0) {
206 throw new RuntimeException("invalid offset: " + inOfs);
207 }
208 if (inLen > in.length - inOfs) {
209 throw new RuntimeException("input length out of bound: " +
210 inLen + " > " + (in.length - inOfs));
211 }
212 if (inLen % AES_BLOCK_SIZE != 0) {
213 throw new RuntimeException("input length/block size mismatch: " +
214 inLen);
215 }
216
217 // These two checks are for C2 checking
218 if (st.length != 2) {
219 throw new RuntimeException("internal state has invalid length: " +
220 st.length);
221 }
222 if (subH.length != 2) {
223 throw new RuntimeException("internal subkeyH has invalid length: " +
224 subH.length);
225 }
226 }
227 /*
228 * This is an intrinsified method. The method's argument list must match
229 * the hotspot signature. This method and methods called by it, cannot
230 * throw exceptions or allocate arrays as it will breaking intrinsics
231 */
232 @HotSpotIntrinsicCandidate
233 private static void processBlocks(byte[] data, int inOfs, int blocks, long[] st, long[] subH) {
234 int offset = inOfs;
235 while (blocks > 0) {
236 processBlock(data, offset, st, subH);
237 blocks--;
238 offset += AES_BLOCK_SIZE;
239 }
240 }
241
242 byte[] digest() {
243 byte[] result = new byte[AES_BLOCK_SIZE];
244 putLong(result, 0, state[0]);
245 putLong(result, 8, state[1]);
246 reset();
247 return result;
248 }
249 }