1 /*
2 * Copyright (c) 2003, 2017, 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.*;
29 import java.security.spec.AlgorithmParameterSpec;
30
31 import javax.crypto.*;
32
33 /**
34 * Implementation of the ARCFOUR cipher, an algorithm apparently compatible
35 * with RSA Security's RC4(tm) cipher. The description of this algorithm was
36 * taken from Bruce Schneier's book Applied Cryptography, 2nd ed.,
37 * section 17.1.
38 *
39 * We support keys from 40 to 1024 bits. ARCFOUR would allow for keys shorter
40 * than 40 bits, but that is too insecure for us to permit.
41 *
42 * Note that we subclass CipherSpi directly and do not use the CipherCore
43 * framework. That was designed to simplify implementation of block ciphers
44 * and does not offer any advantages for stream ciphers such as ARCFOUR.
45 *
46 * @since 1.5
47 * @author Andreas Sterbenz
48 */
49 public final class ARCFOURCipher extends CipherSpi {
50
51 // state array S, 256 entries. The entries are 8-bit, but we use an int[]
52 // because int arithmetic is much faster than in Java than bytes.
53 private final int[] S;
54
55 // state indices i and j. Called is and js to avoid collision with
56 // local variables. 'is' is set to -1 after a call to doFinal()
57 private int is, js;
58
59 // the bytes of the last key used (if any)
60 // we need this to re-initialize after a call to doFinal()
61 private byte[] lastKey;
62
63 // called by the JCE framework
64 public ARCFOURCipher() {
65 S = new int[256];
66 }
67
68 // core key setup code. initializes S, is, and js
69 // assumes key is non-null and between 40 and 1024 bit
70 private void init(byte[] key) {
71 // initialize S[i] to i
72 for (int i = 0; i < 256; i++) {
73 S[i] = i;
74 }
75
76 // we avoid expanding key to 256 bytes and instead keep a separate
77 // counter ki = i mod key.length.
78 for (int i = 0, j = 0, ki = 0; i < 256; i++) {
79 int Si = S[i];
80 j = (j + Si + key[ki]) & 0xff;
81 S[i] = S[j];
82 S[j] = Si;
83 ki++;
84 if (ki == key.length) {
85 ki = 0;
86 }
87 }
88
89 // set indices to 0
90 is = 0;
91 js = 0;
92 }
93
94 // core crypt code. OFB style, so works for both encryption and decryption
95 private void crypt(byte[] in, int inOfs, int inLen, byte[] out,
96 int outOfs) {
97 if (is < 0) {
98 // doFinal() was called, need to reset the cipher to initial state
99 init(lastKey);
100 }
101 while (inLen-- > 0) {
102 is = (is + 1) & 0xff;
103 int Si = S[is];
104 js = (js + Si) & 0xff;
105 int Sj = S[js];
106 S[is] = Sj;
107 S[js] = Si;
108 out[outOfs++] = (byte)(in[inOfs++] ^ S[(Si + Sj) & 0xff]);
109 }
110 }
111
112 // Modes do not make sense with stream ciphers, but allow ECB
113 // see JCE spec.
114 protected void engineSetMode(String mode) throws NoSuchAlgorithmException {
115 if (mode.equalsIgnoreCase("ECB") == false) {
116 throw new NoSuchAlgorithmException("Unsupported mode " + mode);
117 }
118 }
119
120 // Padding does not make sense with stream ciphers, but allow NoPadding
121 // see JCE spec.
122 protected void engineSetPadding(String padding)
123 throws NoSuchPaddingException {
124 if (padding.equalsIgnoreCase("NoPadding") == false) {
125 throw new NoSuchPaddingException("Padding must be NoPadding");
126 }
127 }
128
129 // Return 0 to indicate stream cipher
130 // see JCE spec.
131 protected int engineGetBlockSize() {
132 return 0;
133 }
134
135 // output length is always the same as input length
136 // see JCE spec
137 protected int engineGetOutputSize(int inputLen) {
138 return inputLen;
139 }
140
141 // no IV, return null
142 // see JCE spec
143 protected byte[] engineGetIV() {
144 return null;
145 }
146
147 // no parameters
148 // see JCE spec
149 protected AlgorithmParameters engineGetParameters() {
150 return null;
151 }
152
153 // see JCE spec
154 protected void engineInit(int opmode, Key key, SecureRandom random)
155 throws InvalidKeyException {
156 init(opmode, key);
157 }
158
159 // see JCE spec
160 protected void engineInit(int opmode, Key key,
161 AlgorithmParameterSpec params, SecureRandom random)
162 throws InvalidKeyException, InvalidAlgorithmParameterException {
163 if (params != null) {
164 throw new InvalidAlgorithmParameterException
165 ("Parameters not supported");
166 }
167 init(opmode, key);
168 }
169
170 // see JCE spec
171 protected void engineInit(int opmode, Key key,
172 AlgorithmParameters params, SecureRandom random)
173 throws InvalidKeyException, InvalidAlgorithmParameterException {
174 if (params != null) {
175 throw new InvalidAlgorithmParameterException
176 ("Parameters not supported");
177 }
178 init(opmode, key);
179 }
180
181 // init method. Check opmode and key, then call init(byte[]).
182 private void init(int opmode, Key key) throws InvalidKeyException {
183 if ((opmode < Cipher.ENCRYPT_MODE) || (opmode > Cipher.UNWRAP_MODE)) {
184 throw new InvalidKeyException("Unknown opmode: " + opmode);
185 }
186 lastKey = getEncodedKey(key);
187 init(lastKey);
188 }
189
190 // return the encoding of key if key is a valid ARCFOUR key.
191 // otherwise, throw an InvalidKeyException
192 private static byte[] getEncodedKey(Key key) throws InvalidKeyException {
193 String keyAlg = key.getAlgorithm();
194 if (!keyAlg.equals("RC4") && !keyAlg.equals("ARCFOUR")) {
195 throw new InvalidKeyException("Not an ARCFOUR key: " + keyAlg);
196 }
197 if ("RAW".equals(key.getFormat()) == false) {
198 throw new InvalidKeyException("Key encoding format must be RAW");
199 }
200 byte[] encodedKey = key.getEncoded();
201 if ((encodedKey.length < 5) || (encodedKey.length > 128)) {
202 throw new InvalidKeyException
203 ("Key length must be between 40 and 1024 bit");
204 }
205 return encodedKey;
206 }
207
208 // see JCE spec
209 protected byte[] engineUpdate(byte[] in, int inOfs, int inLen) {
210 byte[] out = new byte[inLen];
211 crypt(in, inOfs, inLen, out, 0);
212 return out;
213 }
214
215 // see JCE spec
216 protected int engineUpdate(byte[] in, int inOfs, int inLen,
217 byte[] out, int outOfs) throws ShortBufferException {
218 if (out.length - outOfs < inLen) {
219 throw new ShortBufferException("Output buffer too small");
220 }
221 crypt(in, inOfs, inLen, out, outOfs);
222 return inLen;
223 }
224
225 // see JCE spec
226 protected byte[] engineDoFinal(byte[] in, int inOfs, int inLen) {
227 byte[] out = engineUpdate(in, inOfs, inLen);
228 is = -1;
229 return out;
230 }
231
232 // see JCE spec
233 protected int engineDoFinal(byte[] in, int inOfs, int inLen,
234 byte[] out, int outOfs) throws ShortBufferException {
235 int outLen = engineUpdate(in, inOfs, inLen, out, outOfs);
236 is = -1;
237 return outLen;
238 }
239
240 // see JCE spec
241 protected byte[] engineWrap(Key key) throws IllegalBlockSizeException,
242 InvalidKeyException {
243 byte[] encoded = key.getEncoded();
244 if ((encoded == null) || (encoded.length == 0)) {
245 throw new InvalidKeyException("Could not obtain encoded key");
246 }
247 return engineDoFinal(encoded, 0, encoded.length);
248 }
249
250 // see JCE spec
251 protected Key engineUnwrap(byte[] wrappedKey, String algorithm,
252 int type) throws InvalidKeyException, NoSuchAlgorithmException {
253 byte[] encoded = engineDoFinal(wrappedKey, 0, wrappedKey.length);
254 return ConstructKeys.constructKey(encoded, algorithm, type);
255 }
256
257 // see JCE spec
258 protected int engineGetKeySize(Key key) throws InvalidKeyException {
259 byte[] encodedKey = getEncodedKey(key);
260 return Math.multiplyExact(encodedKey.length, 8);
261 }
262
263 }