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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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java/pkg/com/sun/crypto/provider/CounterMode.java+210−0
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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+
26+package com.sun.crypto.provider;
27+
28+import 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+ */
42+final 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+}