1 package org.bouncycastle.crypto.digests;
2
3 /*-
4 * ╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲
5 * SNMP Java Client
6 * ჻჻჻჻჻჻
7 * Copyright 2023 Sentry Software, Westhawk
8 * ჻჻჻჻჻჻
9 * This program is free software: you can redistribute it and/or modify
10 * it under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation, either version 3 of the
12 * License, or (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Lesser Public License for more details.
18 *
19 * You should have received a copy of the GNU General Lesser Public
20 * License along with this program. If not, see
21 * <http://www.gnu.org/licenses/lgpl-3.0.html>.
22 * ╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱
23 */
24
25 import org.bouncycastle.crypto.Digest;
26
27 /**
28 * base implementation of MD4 family style digest as outlined in
29 * "Handbook of Applied Cryptography", pages 344 - 347.
30 */
31 public abstract class GeneralDigest
32 implements Digest
33 {
34 private byte[] xBuf;
35 private int xBufOff;
36
37 private long byteCount;
38
39 /**
40 * Standard constructor
41 */
42 protected GeneralDigest()
43 {
44 xBuf = new byte[4];
45 xBufOff = 0;
46 }
47
48 /**
49 * Copy constructor. We are using copy constructors in place
50 * of the Object.clone() interface as this interface is not
51 * supported by J2ME.
52 */
53 protected GeneralDigest(GeneralDigest t)
54 {
55 xBuf = new byte[t.xBuf.length];
56 System.arraycopy(t.xBuf, 0, xBuf, 0, t.xBuf.length);
57
58 xBufOff = t.xBufOff;
59 byteCount = t.byteCount;
60 }
61
62 public void update(
63 byte in)
64 {
65 xBuf[xBufOff++] = in;
66
67 if (xBufOff == xBuf.length)
68 {
69 processWord(xBuf, 0);
70 xBufOff = 0;
71 }
72
73 byteCount++;
74 }
75
76 public void update(
77 byte[] in,
78 int inOff,
79 int len)
80 {
81 //
82 // fill the current word
83 //
84 while ((xBufOff != 0) && (len > 0))
85 {
86 update(in[inOff]);
87
88 inOff++;
89 len--;
90 }
91
92 //
93 // process whole words.
94 //
95 while (len > xBuf.length)
96 {
97 processWord(in, inOff);
98
99 inOff += xBuf.length;
100 len -= xBuf.length;
101 byteCount += xBuf.length;
102 }
103
104 //
105 // load in the remainder.
106 //
107 while (len > 0)
108 {
109 update(in[inOff]);
110
111 inOff++;
112 len--;
113 }
114 }
115
116 public void finish()
117 {
118 long bitLength = (byteCount << 3);
119
120 //
121 // add the pad bytes.
122 //
123 update((byte)128);
124
125 while (xBufOff != 0)
126 {
127 update((byte)0);
128 }
129
130 processLength(bitLength);
131
132 processBlock();
133 }
134
135 public void reset()
136 {
137 byteCount = 0;
138
139 xBufOff = 0;
140 for ( int i = 0; i < xBuf.length; i++ ) {
141 xBuf[i] = 0;
142 }
143 }
144
145 protected abstract void processWord(byte[] in, int inOff);
146
147 protected abstract void processLength(long bitLength);
148
149 protected abstract void processBlock();
150 }