Source for gnu.javax.crypto.mac.BaseMac

   1: /* BaseMac.java --
   2:    Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc.
   3: 
   4: This file is a 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 of the License, or (at
   9: your option) 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; if not, write to the Free Software
  18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19: 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.mac;
  40: 
  41: import gnu.java.security.hash.IMessageDigest;
  42: 
  43: import java.security.InvalidKeyException;
  44: import java.util.Map;
  45: 
  46: /**
  47:  * A base abstract class to facilitate <i>MAC</i> (Message Authentication Code)
  48:  * implementations.
  49:  */
  50: public abstract class BaseMac
  51:     implements IMac
  52: {
  53:   /** The canonical name prefix of the <i>MAC</i>. */
  54:   protected String name;
  55:   /** Reference to the underlying hash algorithm instance. */
  56:   protected IMessageDigest underlyingHash;
  57:   /** The length of the truncated output in bytes. */
  58:   protected int truncatedSize;
  59: 
  60:   /**
  61:    * Trivial constructor for use by concrete subclasses.
  62:    *
  63:    * @param name the canonical name of this instance.
  64:    */
  65:   protected BaseMac(String name)
  66:   {
  67:     super();
  68: 
  69:     this.name = name;
  70:   }
  71: 
  72:   /**
  73:    * Trivial constructor for use by concrete subclasses.
  74:    *
  75:    * @param name the canonical name of this instance.
  76:    * @param underlyingHash the underlying message digest algorithm instance.
  77:    */
  78:   protected BaseMac(String name, IMessageDigest underlyingHash)
  79:   {
  80:     this(name);
  81: 
  82:     if (underlyingHash != null)
  83:       truncatedSize = underlyingHash.hashSize();
  84:     this.underlyingHash = underlyingHash;
  85:   }
  86: 
  87:   public String name()
  88:   {
  89:     return name;
  90:   }
  91: 
  92:   public int macSize()
  93:   {
  94:     return truncatedSize;
  95:   }
  96: 
  97:   public void update(byte b)
  98:   {
  99:     underlyingHash.update(b);
 100:   }
 101: 
 102:   public void update(byte[] b, int offset, int len)
 103:   {
 104:     underlyingHash.update(b, offset, len);
 105:   }
 106: 
 107:   public void reset()
 108:   {
 109:     underlyingHash.reset();
 110:   }
 111: 
 112:   public Object clone() throws CloneNotSupportedException
 113:   {
 114:     BaseMac result = (BaseMac) super.clone();
 115:     if (this.underlyingHash != null)
 116:       result.underlyingHash = (IMessageDigest) this.underlyingHash.clone();
 117: 
 118:     return result;
 119:   }
 120: 
 121:   public abstract void init(Map attributes) throws InvalidKeyException,
 122:       IllegalStateException;
 123: 
 124:   public abstract byte[] digest();
 125: 
 126:   public abstract boolean selfTest();
 127: }