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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

Showing the changes to java/pkg/com/sun/crypto/provider/CounterMode.java (1 of 18352 files). Show all

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1/*
2 * Copyright (c) 2002, 2007, 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
26package com.sun.crypto.provider;
27
28import java.security.InvalidKeyException;
29
30/**
31 * This class represents ciphers in counter (CTR) mode.
32 *
33 * <p>This mode is implemented independently of a particular cipher.
34 * Ciphers to which this mode should apply (e.g., DES) must be
35 * <i>plugged-in</i> using the constructor.
36 *
37 * <p>NOTE: This class does not deal with buffering or padding.
38 *
39 * @author Andreas Sterbenz
40 * @since 1.4.2
41 */
42final class CounterMode extends FeedbackCipher {
43
44 // current counter value
45 private final byte[] counter;
46
47 // encrypted bytes of the previous counter value
48 private final byte[] encryptedCounter;
49
50 // number of bytes in encryptedCounter already used up
51 private int used;
52
53 // variables for save/restore calls
54 private byte[] counterSave = null;
55 private byte[] encryptedCounterSave = null;
56 private int usedSave = 0;
57
58 CounterMode(SymmetricCipher embeddedCipher) {
59 super(embeddedCipher);
60 counter = new byte[blockSize];
61 encryptedCounter = new byte[blockSize];
62 }
63
64 /**
65 * Gets the name of the feedback mechanism
66 *
67 * @return the name of the feedback mechanism
68 */
69 String getFeedback() {
70 return "CTR";
71 }
72
73 /**
74 * Resets the iv to its original value.
75 * This is used when doFinal is called in the Cipher class, so that the
76 * cipher can be reused (with its original iv).
77 */
78 void reset() {
79 System.arraycopy(iv, 0, counter, 0, blockSize);
80 used = blockSize;
81 }
82
83 /**
84 * Save the current content of this cipher.
85 */
86 void save() {
87 if (counterSave == null) {
88 counterSave = new byte[blockSize];
89 encryptedCounterSave = new byte[blockSize];
90 }
91 System.arraycopy(counter, 0, counterSave, 0, blockSize);
92 System.arraycopy(encryptedCounter, 0, encryptedCounterSave, 0,
93 blockSize);
94 usedSave = used;
95 }
96
97 /**
98 * Restores the content of this cipher to the previous saved one.
99 */
100 void restore() {
101 System.arraycopy(counterSave, 0, counter, 0, blockSize);
102 System.arraycopy(encryptedCounterSave, 0, encryptedCounter, 0,
103 blockSize);
104 used = usedSave;
105 }
106
107 /**
108 * Initializes the cipher in the specified mode with the given key
109 * and iv.
110 *
111 * @param decrypting flag indicating encryption or decryption
112 * @param algorithm the algorithm name
113 * @param key the key
114 * @param iv the iv
115 *
116 * @exception InvalidKeyException if the given key is inappropriate for
117 * initializing this cipher
118 */
119 void init(boolean decrypting, String algorithm, byte[] key, byte[] iv)
120 throws InvalidKeyException {
121 if ((key == null) || (iv == null) || (iv.length != blockSize)) {
122 throw new InvalidKeyException("Internal error");
123 }
124 this.iv = iv;
125 reset();
126 // always encrypt mode for embedded cipher
127 embeddedCipher.init(false, algorithm, key);
128 }
129
130 /**
131 * Performs encryption operation.
132 *
133 * <p>The input plain text <code>plain</code>, starting at
134 * <code>plainOffset</code> and ending at
135 * <code>(plainOffset + len - 1)</code>, is encrypted.
136 * The result is stored in <code>cipher</code>, starting at
137 * <code>cipherOffset</code>.
138 *
139 * <p>It is the application's responsibility to make sure that
140 * <code>plainLen</code> is a multiple of the embedded cipher's block size,
141 * as any excess bytes are ignored.
142 *
143 * <p>It is also the application's responsibility to make sure that
144 * <code>init</code> has been called before this method is called.
145 * (This check is omitted here, to avoid double checking.)
146 *
147 * @param in the buffer with the input data to be encrypted
148 * @param inOffset the offset in <code>plain</code>
149 * @param len the length of the input data
150 * @param out the buffer for the result
151 * @param outOff the offset in <code>cipher</code>
152 */
153 void encrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
154 crypt(in, inOff, len, out, outOff);
155 }
156
157 /**
158 * Performs decryption operation.
159 *
160 * <p>The input cipher text <code>cipher</code>, starting at
161 * <code>cipherOffset</code> and ending at
162 * <code>(cipherOffset + len - 1)</code>, is decrypted.
163 * The result is stored in <code>plain</code>, starting at
164 * <code>plainOffset</code>.
165 *
166 * <p>It is the application's responsibility to make sure that
167 * <code>cipherLen</code> is a multiple of the embedded cipher's block
168 * size, as any excess bytes are ignored.
169 *
170 * <p>It is also the application's responsibility to make sure that
171 * <code>init</code> has been called before this method is called.
172 * (This check is omitted here, to avoid double checking.)
173 *
174 * @param in the buffer with the input data to be decrypted
175 * @param inOff the offset in <code>cipherOffset</code>
176 * @param len the length of the input data
177 * @param out the buffer for the result
178 * @param outOff the offset in <code>plain</code>
179 */
180 void decrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
181 crypt(in, inOff, len, out, outOff);
182 }
183
184 /**
185 * Increment the counter value.
186 */
187 private static void increment(byte[] b) {
188 int n = b.length - 1;
189 while ((n >= 0) && (++b[n] == 0)) {
190 n--;
191 }
192 }
193
194 /**
195 * Do the actual encryption/decryption operation.
196 * Essentially we XOR the input plaintext/ciphertext stream with a
197 * keystream generated by encrypting the counter values. Counter values
198 * are encrypted on demand.
199 */
200 private void crypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
201 while (len-- > 0) {
202 if (used >= blockSize) {
203 embeddedCipher.encryptBlock(counter, 0, encryptedCounter, 0);
204 increment(counter);
205 used = 0;
206 }
207 out[outOff++] = (byte)(in[inOff++] ^ encryptedCounter[used++]);
208 }
209 }
210}