1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
/*
* Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.crypto.provider;
import java.security.InvalidKeyException;
import java.security.ProviderException;
/**
* This class represents ciphers in Plaintext Cipher Block Chaining (PCBC)
* mode.
*
* <p>This mode is implemented independently of a particular cipher.
* Ciphers to which this mode should apply (e.g., DES) must be
* <i>plugged-in</i> using the constructor.
*
* <p>NOTE: This class does not deal with buffering or padding.
*
* @author Gigi Ankeny
*/
final class PCBC extends FeedbackCipher {
/*
* output buffer
*/
private final byte[] k;
// variables for save/restore calls
private byte[] kSave = null;
PCBC(SymmetricCipher embeddedCipher) {
super(embeddedCipher);
k = new byte[blockSize];
}
/**
* Gets the name of this feedback mode.
*
* @return the string <code>PCBC</code>
*/
String getFeedback() {
return "PCBC";
}
/**
* Initializes the cipher in the specified mode with the given key
* and iv.
*
* @param decrypting flag indicating encryption or decryption
* @param algorithm the algorithm name
* @param key the key
* @param iv the iv
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this cipher
*/
void init(boolean decrypting, String algorithm, byte[] key, byte[] iv)
throws InvalidKeyException {
if ((key == null) || (iv == null) || (iv.length != blockSize)) {
throw new InvalidKeyException("Internal error");
}
this.iv = iv;
reset();
embeddedCipher.init(decrypting, algorithm, key);
}
/**
* Resets the iv to its original value.
* This is used when doFinal is called in the Cipher class, so that the
* cipher can be reused (with its original iv).
*/
void reset() {
System.arraycopy(iv, 0, k, 0, blockSize);
}
/**
* Save the current content of this cipher.
*/
void save() {
if (kSave == null) {
kSave = new byte[blockSize];
}
System.arraycopy(k, 0, kSave, 0, blockSize);
}
/**
* Restores the content of this cipher to the previous saved one.
*/
void restore() {
System.arraycopy(kSave, 0, k, 0, blockSize);
}
/**
* Performs encryption operation.
*
* <p>The input plain text <code>plain</code>, starting at
* <code>plainOffset</code> and ending at
* <code>(plainOffset + plainLen - 1)</code>, is encrypted.
* The result is stored in <code>cipher</code>, starting at
* <code>cipherOffset</code>.
*
* @param plain the buffer with the input data to be encrypted
* @param plainOffset the offset in <code>plain</code>
* @param plainLen the length of the input data
* @param cipher the buffer for the result
* @param cipherOffset the offset in <code>cipher</code>
* @exception ProviderException if <code>plainLen</code> is not
* a multiple of the block size
* @return the length of the encrypted data
*/
int encrypt(byte[] plain, int plainOffset, int plainLen,
byte[] cipher, int cipherOffset)
{
if ((plainLen % blockSize) != 0) {
throw new ProviderException("Internal error in input buffering");
}
int i;
int endIndex = plainOffset + plainLen;
for (; plainOffset < endIndex;
plainOffset += blockSize, cipherOffset += blockSize) {
for (i = 0; i < blockSize; i++) {
k[i] ^= plain[i + plainOffset];
}
embeddedCipher.encryptBlock(k, 0, cipher, cipherOffset);
for (i = 0; i < blockSize; i++) {
k[i] = (byte)(plain[i + plainOffset] ^ cipher[i + cipherOffset]);
}
}
return plainLen;
}
/**
* Performs decryption operation.
*
* <p>The input cipher text <code>cipher</code>, starting at
* <code>cipherOffset</code> and ending at
* <code>(cipherOffset + cipherLen - 1)</code>, is decrypted.
* The result is stored in <code>plain</code>, starting at
* <code>plainOffset</code>.
*
* @param cipher the buffer with the input data to be decrypted
* @param cipherOffset the offset in <code>cipherOffset</code>
* @param cipherLen the length of the input data
* @param plain the buffer for the result
* @param plainOffset the offset in <code>plain</code>
* @exception ProviderException if <code>cipherLen</code> is not
* a multiple of the block size
* @return the length of the decrypted data
*/
int decrypt(byte[] cipher, int cipherOffset, int cipherLen,
byte[] plain, int plainOffset)
{
if ((cipherLen % blockSize) != 0) {
throw new ProviderException("Internal error in input buffering");
}
int i;
int endIndex = cipherOffset + cipherLen;
for (; cipherOffset < endIndex;
plainOffset += blockSize, cipherOffset += blockSize) {
embeddedCipher.decryptBlock(cipher, cipherOffset,
plain, plainOffset);
for (i = 0; i < blockSize; i++) {
plain[i + plainOffset] ^= k[i];
}
for (i = 0; i < blockSize; i++) {
k[i] = (byte)(plain[i + plainOffset] ^ cipher[i + cipherOffset]);
}
}
return cipherLen;
}
}
|
