Source for gnu.javax.crypto.kwa.BaseKeyWrappingAlgorithm

   1: /* BaseKeyWrappingAlgorithm.java -- FIXME: briefly describe file purpose
   2:    Copyright (C) 2006 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package gnu.javax.crypto.kwa;
  40: 
  41: import gnu.java.security.util.PRNG;
  42: 
  43: import java.security.InvalidKeyException;
  44: import java.util.Collections;
  45: import java.util.Map;
  46: 
  47: import javax.crypto.ShortBufferException;
  48: 
  49: /**
  50:  * A base class to facilitate implementation of concrete Key Wrapping
  51:  * Algorithms.
  52:  */
  53: public abstract class BaseKeyWrappingAlgorithm
  54:      implements IKeyWrappingAlgorithm
  55: {
  56:   /** The canonical name of the key wrapping algorithm. */
  57:   protected String name;
  58:   /** A source of randomness if/when needed by concrete implementations. */
  59:   private PRNG prng;
  60: 
  61:   /**
  62:    * Protected constructor.
  63:    *
  64:    * @param name the key wrapping algorithm canonical name.
  65:    */
  66:   protected BaseKeyWrappingAlgorithm(String name)
  67:   {
  68:     super();
  69:   }
  70: 
  71:   public String name()
  72:   {
  73:     return this.name;
  74:   }
  75: 
  76:   public void init(Map attributes) throws InvalidKeyException
  77:   {
  78:     if (attributes == null)
  79:       attributes = Collections.EMPTY_MAP;
  80: 
  81:     engineInit(attributes);
  82:   }
  83: 
  84:   public int wrap(byte[] in, int inOffset, int length, byte[] out, int outOffset)
  85:       throws ShortBufferException
  86:   {
  87:     if (outOffset < 0)
  88:       throw new IllegalArgumentException("Output offset MUST NOT be negative");
  89:     byte[] result = wrap(in, inOffset, length);
  90:     if (outOffset + result.length > out.length)
  91:       throw new ShortBufferException();
  92:     System.arraycopy(result, 0, out, outOffset, result.length);
  93:     return result.length;
  94:   }
  95: 
  96:   public byte[] wrap(byte[] in, int inOffset, int length)
  97:   {
  98:     if (inOffset < 0)
  99:       throw new IllegalArgumentException("Input offset MUST NOT be negative");
 100:     if (length < 0)
 101:       throw new IllegalArgumentException("Input length MUST NOT be negative");
 102: 
 103:     return engineWrap(in, inOffset, length);
 104:   }
 105: 
 106:   public int unwrap(byte[] in, int inOffset, int length,
 107:                     byte[] out, int outOffset)
 108:       throws ShortBufferException, KeyUnwrappingException
 109:   {
 110:     if (outOffset < 0)
 111:       throw new IllegalArgumentException("Output offset MUST NOT be negative");
 112:     byte[] result = engineUnwrap(in, inOffset, length);
 113:     if (outOffset + result.length > out.length)
 114:       throw new ShortBufferException();
 115:     System.arraycopy(result, 0, out, outOffset, result.length);
 116:     return result.length;
 117:   }
 118: 
 119:   public byte[] unwrap(byte[] in, int inOffset, int length)
 120:       throws KeyUnwrappingException
 121:   {
 122:     if (inOffset < 0)
 123:       throw new IllegalArgumentException("Input offset MUST NOT be negative");
 124:     if (length < 0)
 125:       throw new IllegalArgumentException("Input length MUST NOT be negative");
 126: 
 127:     return engineUnwrap(in, inOffset, length);
 128:   }
 129: 
 130:   protected abstract void engineInit(Map attributes) throws InvalidKeyException;
 131: 
 132:   protected abstract byte[] engineWrap(byte[] in, int inOffset, int length);
 133: 
 134:   protected abstract byte[] engineUnwrap(byte[] in, int inOffset, int length)
 135:       throws KeyUnwrappingException;
 136: 
 137:   /** @return a strong pseudo-random number generator if/when needed. */
 138:   protected PRNG getDefaultPRNG()
 139:   {
 140:     if (prng == null)
 141:       prng = PRNG.getInstance();
 142: 
 143:     return prng;
 144:   }
 145: }