1 /*
2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.security.provider;
27
28 import java.security.MessageDigestSpi;
29 import java.security.DigestException;
30 import java.security.ProviderException;
31
32 /**
33 * Common base message digest implementation for the Sun provider.
34 * It implements all the JCA methods as suitable for a Java message digest
35 * implementation of an algorithm based on a compression function (as all
36 * commonly used algorithms are). The individual digest subclasses only need to
37 * implement the following methods:
38 *
39 * . abstract void implCompress(byte[] b, int ofs);
40 * . abstract void implDigest(byte[] out, int ofs);
41 * . abstract void implReset();
42 *
43 * See the inline documentation for details.
44 *
45 * @since 1.5
46 * @author Andreas Sterbenz
47 */
48 abstract class DigestBase extends MessageDigestSpi implements Cloneable {
49
50 // one element byte array, temporary storage for update(byte)
51 private byte[] oneByte;
52
53 // algorithm name to use in the exception message
54 private final String algorithm;
55 // length of the message digest in bytes
56 private final int digestLength;
57
58 // size of the input to the compression function in bytes
59 private final int blockSize;
60 // buffer to store partial blocks, blockSize bytes large
61 // Subclasses should not access this array directly except possibly in their
62 // implDigest() method. See MD5.java as an example.
63 byte[] buffer;
64 // offset into buffer
65 private int bufOfs;
66
67 // number of bytes processed so far. subclasses should not modify
68 // this value.
69 // also used as a flag to indicate reset status
70 // -1: need to call engineReset() before next call to update()
71 // 0: is already reset
72 long bytesProcessed;
73
74 /**
75 * Main constructor.
76 */
77 DigestBase(String algorithm, int digestLength, int blockSize) {
78 super();
79 this.algorithm = algorithm;
80 this.digestLength = digestLength;
81 this.blockSize = blockSize;
82 buffer = new byte[blockSize];
83 }
84
85 // return digest length. See JCA doc.
86 protected final int engineGetDigestLength() {
87 return digestLength;
88 }
89
90 // single byte update. See JCA doc.
91 protected final void engineUpdate(byte b) {
92 if (oneByte == null) {
93 oneByte = new byte[1];
94 }
95 oneByte[0] = b;
96 engineUpdate(oneByte, 0, 1);
97 }
98
99 // array update. See JCA doc.
100 protected final void engineUpdate(byte[] b, int ofs, int len) {
101 if (len == 0) {
102 return;
103 }
104 if ((ofs < 0) || (len < 0) || (ofs > b.length - len)) {
105 throw new ArrayIndexOutOfBoundsException();
106 }
107 if (bytesProcessed < 0) {
108 engineReset();
109 }
110 bytesProcessed += len;
111 // if buffer is not empty, we need to fill it before proceeding
112 if (bufOfs != 0) {
113 int n = Math.min(len, blockSize - bufOfs);
114 System.arraycopy(b, ofs, buffer, bufOfs, n);
115 bufOfs += n;
116 ofs += n;
117 len -= n;
118 if (bufOfs >= blockSize) {
119 // compress completed block now
120 implCompress(buffer, 0);
121 bufOfs = 0;
122 }
123 }
124 // compress complete blocks
125 while (len >= blockSize) {
126 implCompress(b, ofs);
127 len -= blockSize;
128 ofs += blockSize;
129 }
130 // copy remainder to buffer
131 if (len > 0) {
132 System.arraycopy(b, ofs, buffer, 0, len);
133 bufOfs = len;
134 }
135 }
136
137 // reset this object. See JCA doc.
138 protected final void engineReset() {
139 if (bytesProcessed == 0) {
140 // already reset, ignore
141 return;
142 }
143 implReset();
144 bufOfs = 0;
145 bytesProcessed = 0;
146 }
147
148 // return the digest. See JCA doc.
149 protected final byte[] engineDigest() {
150 byte[] b = new byte[digestLength];
151 try {
152 engineDigest(b, 0, b.length);
153 } catch (DigestException e) {
154 throw (ProviderException)
155 new ProviderException("Internal error").initCause(e);
156 }
157 return b;
158 }
159
160 // return the digest in the specified array. See JCA doc.
161 protected final int engineDigest(byte[] out, int ofs, int len)
162 throws DigestException {
163 if (len < digestLength) {
164 throw new DigestException("Length must be at least "
165 + digestLength + " for " + algorithm + "digests");
166 }
167 if ((ofs < 0) || (len < 0) || (ofs > out.length - len)) {
168 throw new DigestException("Buffer too short to store digest");
169 }
170 if (bytesProcessed < 0) {
171 engineReset();
172 }
173 implDigest(out, ofs);
174 bytesProcessed = -1;
175 return digestLength;
176 }
177
178 /**
179 * Core compression function. Processes blockSize bytes at a time
180 * and updates the state of this object.
181 */
182 abstract void implCompress(byte[] b, int ofs);
183
184 /**
185 * Return the digest. Subclasses do not need to reset() themselves,
186 * DigestBase calls implReset() when necessary.
187 */
188 abstract void implDigest(byte[] out, int ofs);
189
190 /**
191 * Reset subclass specific state to their initial values. DigestBase
192 * calls this method when necessary.
193 */
194 abstract void implReset();
195
196 public Object clone() throws CloneNotSupportedException {
197 DigestBase copy = (DigestBase) super.clone();
198 copy.buffer = copy.buffer.clone();
199 return copy;
200 }
201
202 // padding used for the MD5, and SHA-* message digests
203 static final byte[] padding;
204
205 static {
206 // we need 128 byte padding for SHA-384/512
207 // and an additional 8 bytes for the high 8 bytes of the 16
208 // byte bit counter in SHA-384/512
209 padding = new byte[136];
210 padding[0] = (byte)0x80;
211 }
212 }