| /* |
| * Copyright (c) 2003, 2010, 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.*; |
| import java.security.spec.AlgorithmParameterSpec; |
| |
| import javax.crypto.*; |
| |
| /** |
| * Implementation of the ARCFOUR cipher, an algorithm apparently compatible |
| * with RSA Security's RC4(tm) cipher. The description of this algorithm was |
| * taken from Bruce Schneier's book Applied Cryptography, 2nd ed., |
| * section 17.1. |
| * |
| * We support keys from 40 to 1024 bits. ARCFOUR would allow for keys shorter |
| * than 40 bits, but that is too insecure for us to permit. |
| * |
| * Note that we subclass CipherSpi directly and do not use the CipherCore |
| * framework. That was designed to simplify implementation of block ciphers |
| * and does not offer any advantages for stream ciphers such as ARCFOUR. |
| * |
| * @since 1.5 |
| * @author Andreas Sterbenz |
| */ |
| public final class ARCFOURCipher extends CipherSpi { |
| |
| // state array S, 256 entries. The entries are 8-bit, but we use an int[] |
| // because int arithmetic is much faster than in Java than bytes. |
| private final int[] S; |
| |
| // state indices i and j. Called is and js to avoid collision with |
| // local variables. 'is' is set to -1 after a call to doFinal() |
| private int is, js; |
| |
| // the bytes of the last key used (if any) |
| // we need this to re-initialize after a call to doFinal() |
| private byte[] lastKey; |
| |
| // called by the JCE framework |
| public ARCFOURCipher() { |
| S = new int[256]; |
| } |
| |
| // core key setup code. initializes S, is, and js |
| // assumes key is non-null and between 40 and 1024 bit |
| private void init(byte[] key) { |
| // initialize S[i] to i |
| for (int i = 0; i < 256; i++) { |
| S[i] = i; |
| } |
| |
| // we avoid expanding key to 256 bytes and instead keep a separate |
| // counter ki = i mod key.length. |
| for (int i = 0, j = 0, ki = 0; i < 256; i++) { |
| int Si = S[i]; |
| j = (j + Si + key[ki]) & 0xff; |
| S[i] = S[j]; |
| S[j] = Si; |
| ki++; |
| if (ki == key.length) { |
| ki = 0; |
| } |
| } |
| |
| // set indices to 0 |
| is = 0; |
| js = 0; |
| } |
| |
| // core crypt code. OFB style, so works for both encryption and decryption |
| private void crypt(byte[] in, int inOfs, int inLen, byte[] out, |
| int outOfs) { |
| if (is < 0) { |
| // doFinal() was called, need to reset the cipher to initial state |
| init(lastKey); |
| } |
| while (inLen-- > 0) { |
| is = (is + 1) & 0xff; |
| int Si = S[is]; |
| js = (js + Si) & 0xff; |
| int Sj = S[js]; |
| S[is] = Sj; |
| S[js] = Si; |
| out[outOfs++] = (byte)(in[inOfs++] ^ S[(Si + Sj) & 0xff]); |
| } |
| } |
| |
| // Modes do not make sense with stream ciphers, but allow ECB |
| // see JCE spec. |
| protected void engineSetMode(String mode) throws NoSuchAlgorithmException { |
| if (mode.equalsIgnoreCase("ECB") == false) { |
| throw new NoSuchAlgorithmException("Unsupported mode " + mode); |
| } |
| } |
| |
| // Padding does not make sense with stream ciphers, but allow NoPadding |
| // see JCE spec. |
| protected void engineSetPadding(String padding) |
| throws NoSuchPaddingException { |
| if (padding.equalsIgnoreCase("NoPadding") == false) { |
| throw new NoSuchPaddingException("Padding must be NoPadding"); |
| } |
| } |
| |
| // Return 0 to indicate stream cipher |
| // see JCE spec. |
| protected int engineGetBlockSize() { |
| return 0; |
| } |
| |
| // output length is always the same as input length |
| // see JCE spec |
| protected int engineGetOutputSize(int inputLen) { |
| return inputLen; |
| } |
| |
| // no IV, return null |
| // see JCE spec |
| protected byte[] engineGetIV() { |
| return null; |
| } |
| |
| // no parameters |
| // see JCE spec |
| protected AlgorithmParameters engineGetParameters() { |
| return null; |
| } |
| |
| // see JCE spec |
| protected void engineInit(int opmode, Key key, SecureRandom random) |
| throws InvalidKeyException { |
| init(opmode, key); |
| } |
| |
| // see JCE spec |
| protected void engineInit(int opmode, Key key, |
| AlgorithmParameterSpec params, SecureRandom random) |
| throws InvalidKeyException, InvalidAlgorithmParameterException { |
| if (params != null) { |
| throw new InvalidAlgorithmParameterException |
| ("Parameters not supported"); |
| } |
| init(opmode, key); |
| } |
| |
| // see JCE spec |
| protected void engineInit(int opmode, Key key, |
| AlgorithmParameters params, SecureRandom random) |
| throws InvalidKeyException, InvalidAlgorithmParameterException { |
| if (params != null) { |
| throw new InvalidAlgorithmParameterException |
| ("Parameters not supported"); |
| } |
| init(opmode, key); |
| } |
| |
| // init method. Check opmode and key, then call init(byte[]). |
| private void init(int opmode, Key key) throws InvalidKeyException { |
| if ((opmode < Cipher.ENCRYPT_MODE) || (opmode > Cipher.UNWRAP_MODE)) { |
| throw new InvalidKeyException("Unknown opmode: " + opmode); |
| } |
| lastKey = getEncodedKey(key); |
| init(lastKey); |
| } |
| |
| // return the encoding of key if key is a valid ARCFOUR key. |
| // otherwise, throw an InvalidKeyException |
| private static byte[] getEncodedKey(Key key) throws InvalidKeyException { |
| String keyAlg = key.getAlgorithm(); |
| if (!keyAlg.equals("RC4") && !keyAlg.equals("ARCFOUR")) { |
| throw new InvalidKeyException("Not an ARCFOUR key: " + keyAlg); |
| } |
| if ("RAW".equals(key.getFormat()) == false) { |
| throw new InvalidKeyException("Key encoding format must be RAW"); |
| } |
| byte[] encodedKey = key.getEncoded(); |
| if ((encodedKey.length < 5) || (encodedKey.length > 128)) { |
| throw new InvalidKeyException |
| ("Key length must be between 40 and 1024 bit"); |
| } |
| return encodedKey; |
| } |
| |
| // see JCE spec |
| protected byte[] engineUpdate(byte[] in, int inOfs, int inLen) { |
| byte[] out = new byte[inLen]; |
| crypt(in, inOfs, inLen, out, 0); |
| return out; |
| } |
| |
| // see JCE spec |
| protected int engineUpdate(byte[] in, int inOfs, int inLen, |
| byte[] out, int outOfs) throws ShortBufferException { |
| if (out.length - outOfs < inLen) { |
| throw new ShortBufferException("Output buffer too small"); |
| } |
| crypt(in, inOfs, inLen, out, outOfs); |
| return inLen; |
| } |
| |
| // see JCE spec |
| protected byte[] engineDoFinal(byte[] in, int inOfs, int inLen) { |
| byte[] out = engineUpdate(in, inOfs, inLen); |
| is = -1; |
| return out; |
| } |
| |
| // see JCE spec |
| protected int engineDoFinal(byte[] in, int inOfs, int inLen, |
| byte[] out, int outOfs) throws ShortBufferException { |
| int outLen = engineUpdate(in, inOfs, inLen, out, outOfs); |
| is = -1; |
| return outLen; |
| } |
| |
| // see JCE spec |
| protected byte[] engineWrap(Key key) throws IllegalBlockSizeException, |
| InvalidKeyException { |
| byte[] encoded = key.getEncoded(); |
| if ((encoded == null) || (encoded.length == 0)) { |
| throw new InvalidKeyException("Could not obtain encoded key"); |
| } |
| return engineDoFinal(encoded, 0, encoded.length); |
| } |
| |
| // see JCE spec |
| protected Key engineUnwrap(byte[] wrappedKey, String algorithm, |
| int type) throws InvalidKeyException, NoSuchAlgorithmException { |
| byte[] encoded = engineDoFinal(wrappedKey, 0, wrappedKey.length); |
| return ConstructKeys.constructKey(encoded, algorithm, type); |
| } |
| |
| // see JCE spec |
| protected int engineGetKeySize(Key key) throws InvalidKeyException { |
| byte[] encodedKey = getEncodedKey(key); |
| return encodedKey.length << 3; |
| } |
| |
| } |