| /* BasePad.java -- |
| Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc. |
| |
| This file is a part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or (at |
| your option) any later version. |
| |
| GNU Classpath 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 for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; if not, write to the Free Software |
| Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 |
| USA |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.javax.crypto.pad; |
| |
| import gnu.java.security.Configuration; |
| |
| import java.util.Map; |
| import java.util.logging.Level; |
| import java.util.logging.Logger; |
| |
| /** |
| * An abstract class to facilitate implementing padding algorithms. |
| */ |
| public abstract class BasePad |
| implements IPad |
| { |
| private static final Logger log = Logger.getLogger(BasePad.class.getName()); |
| /** The canonical name prefix of the padding algorithm. */ |
| protected String name; |
| /** The block size, in bytes, for this instance. */ |
| protected int blockSize; |
| |
| /** Trivial constructor for use by concrete subclasses. */ |
| protected BasePad(final String name) |
| { |
| super(); |
| |
| this.name = name; |
| blockSize = -1; |
| } |
| |
| public String name() |
| { |
| final StringBuffer sb = new StringBuffer(name); |
| if (blockSize != -1) |
| sb.append('-').append(String.valueOf(8 * blockSize)); |
| return sb.toString(); |
| } |
| |
| public void init(final int bs) throws IllegalStateException |
| { |
| if (blockSize != -1) |
| throw new IllegalStateException(); |
| blockSize = bs; |
| setup(); |
| } |
| |
| /** |
| * Initialises the algorithm with designated attributes. Names, valid and/or |
| * recognisable by all concrete implementations are described in {@link IPad} |
| * class documentation. Other algorithm-specific attributes MUST be documented |
| * in the implementation class of that padding algorithm. |
| * <p> |
| * For compatibility reasons, this method is not declared <i>abstract</i>. |
| * Furthermore, and unless overridden, the default implementation will throw |
| * an {@link UnsupportedOperationException}. Concrete padding algorithms MUST |
| * override this method if they wish to offer an initialisation method that |
| * allows for other than the padding block size parameter to be specified. |
| * |
| * @param attributes a set of name-value pairs that describes the desired |
| * future behaviour of this instance. |
| * @exception IllegalStateException if the instance is already initialised. |
| * @exception IllegalArgumentException if the block size value is invalid. |
| */ |
| public void init(Map attributes) throws IllegalStateException |
| { |
| throw new UnsupportedOperationException(); |
| } |
| |
| public void reset() |
| { |
| blockSize = -1; |
| } |
| |
| /** |
| * A default implementation of a correctness test that exercises the padder |
| * implementation, using block sizes varying from 2 to 256 bytes. |
| * |
| * @return <code>true</code> if the concrete implementation correctly unpads |
| * what it pads for all tested block sizes. Returns <code>false</code> |
| * if the test fails for any block size. |
| */ |
| public boolean selfTest() |
| { |
| final byte[] in = new byte[1024]; |
| for (int bs = 2; bs < 256; bs++) |
| if (! test1BlockSize(bs, in)) |
| return false; |
| return true; |
| } |
| |
| /** |
| * The basic symmetric test for a padder given a specific block size. |
| * <p> |
| * The code ensures that the implementation is capable of unpadding what it |
| * pads. |
| * |
| * @param size the block size to test. |
| * @param buffer a work buffer. It is exposed as an argument for this method |
| * to reduce un-necessary object allocations. |
| * @return <code>true</code> if the test passes; <code>false</code> |
| * otherwise. |
| */ |
| protected boolean test1BlockSize(int size, byte[] buffer) |
| { |
| byte[] padBytes; |
| final int offset = 5; |
| final int limit = buffer.length; |
| this.init(size); |
| for (int i = 0; i < limit - offset - blockSize; i++) |
| { |
| padBytes = pad(buffer, offset, i); |
| if (((i + padBytes.length) % blockSize) != 0) |
| { |
| if (Configuration.DEBUG) |
| log.log(Level.SEVERE, |
| "Length of padded text MUST be a multiple of " |
| + blockSize, new RuntimeException(name())); |
| return false; |
| } |
| System.arraycopy(padBytes, 0, buffer, offset + i, padBytes.length); |
| try |
| { |
| if (padBytes.length != unpad(buffer, offset, i + padBytes.length)) |
| { |
| if (Configuration.DEBUG) |
| log.log(Level.SEVERE, |
| "IPad [" + name() + "] failed symmetric operation", |
| new RuntimeException(name())); |
| return false; |
| } |
| } |
| catch (WrongPaddingException x) |
| { |
| if (Configuration.DEBUG) |
| log.throwing(this.getClass().getName(), "test1BlockSize", x); |
| return false; |
| } |
| } |
| this.reset(); |
| return true; |
| } |
| |
| /** |
| * If any additional checks or resource setup must be done by the subclass, |
| * then this is the hook for it. This method will be called before the |
| * {@link #init(int)} method returns. |
| */ |
| public abstract void setup(); |
| |
| public abstract byte[] pad(byte[] in, int off, int len); |
| |
| public abstract int unpad(byte[] in, int off, int len) |
| throws WrongPaddingException; |
| } |