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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 | +} | |