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| 1 | /* | ||
| 2 | * Copyright (c) 2003, 2010, 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 encodedKey.length << 3; | ||
| 261 | } | ||
| 262 | |||
| 263 | } | ||