libjava/classpath/gnu/java/security/key/rsa/GnuRSAPublicKey.java

   1 /* GnuRSAPublicKey.java --
   2    Copyright 2001, 2002, 2003, 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.java.security.key.rsa;
  40
  41 import gnu.java.security.Registry;
  42 import gnu.java.security.action.GetPropertyAction;
  43 import gnu.java.security.key.IKeyPairCodec;
  44
  45 import java.math.BigInteger;
  46 import java.security.AccessController;
  47 import java.security.PublicKey;
  48 import java.security.interfaces.RSAPublicKey;
  49
  50 /**
  51  * An object that encapsulates an RSA public key.
  52  * <p>
  53  * References:
  54  * <ol>
  55  * <li><a
  56  * href="http://www.cosic.esat.kuleuven.ac.be/nessie/workshop/submissions/rsa-pss.zip">
  57  * RSA-PSS Signature Scheme with Appendix, part B.</a><br>
  58  * Primitive specification and supporting documentation.<br>
  59  * Jakob Jonsson and Burt Kaliski.</li>
  60  * </ol>
  61  */
  62 public class GnuRSAPublicKey
  63     extends GnuRSAKey
  64     implements PublicKey, RSAPublicKey
  65 {
  66   /** String representation of this key. Cached for speed. */
  67   private transient String str;
  68
  69   /**
  70    * Conveience constructor. Calls the constructor with 3 arguments passing
  71    * {@link Registry#RAW_ENCODING_ID} as the identifier of the preferred
  72    * encoding format.
  73    *
  74    * @param n the modulus.
  75    * @param e the public exponent.
  76    */
  77   public GnuRSAPublicKey(final BigInteger n, final BigInteger e)
  78   {
  79     this(Registry.RAW_ENCODING_ID, n, e);
  80   }
  81
  82   /**
  83    * Constructs a new instance of <code>GnuRSAPublicKey</code> given the
  84    * designated arguments.
  85    *
  86    * @param preferredFormat the identifier of the preferred encoding format to
  87    *          use when externalizing this key.
  88    * @param n the modulus.
  89    * @param e the public exponent.
  90    */
  91   public GnuRSAPublicKey(int preferredFormat, BigInteger n, BigInteger e)
  92   {
  93     super(preferredFormat == Registry.ASN1_ENCODING_ID ? Registry.X509_ENCODING_ID
  94                                                        : preferredFormat,
  95           n, e);
  96   }
  97
  98   /**
  99    * A class method that takes the output of the <code>encodePublicKey()</code>
 100    * method of an RSA keypair codec object (an instance implementing
 101    * {@link IKeyPairCodec} for RSA keys, and re-constructs an instance of this
 102    * object.
 103    *
 104    * @param k the contents of a previously encoded instance of this object.
 105    * @throws ArrayIndexOutOfBoundsException if there is not enough bytes, in
 106    *           <code>k</code>, to represent a valid encoding of an instance
 107    *           of this object.
 108    * @throws IllegalArgumentException if the byte sequence does not represent a
 109    *           valid encoding of an instance of this object.
 110    */
 111   public static GnuRSAPublicKey valueOf(final byte[] k)
 112   {
 113     // try RAW codec
 114     if (k[0] == Registry.MAGIC_RAW_RSA_PUBLIC_KEY[0])
 115       try
 116         {
 117           return (GnuRSAPublicKey) new RSAKeyPairRawCodec().decodePublicKey(k);
 118         }
 119       catch (IllegalArgumentException ignored)
 120         {
 121         }
 122     // try X.509 codec
 123     return (GnuRSAPublicKey) new RSAKeyPairX509Codec().decodePublicKey(k);
 124   }
 125
 126   /**
 127    * Returns the encoded form of this public key according to the designated
 128    * format.
 129    *
 130    * @param format the desired format identifier of the resulting encoding.
 131    * @return the byte sequence encoding this key according to the designated
 132    *         format.
 133    * @throws IllegalArgumentException if the format is not supported.
 134    * @see RSAKeyPairRawCodec
 135    */
 136   public byte[] getEncoded(final int format)
 137   {
 138     final byte[] result;
 139     switch (format)
 140       {
 141       case IKeyPairCodec.RAW_FORMAT:
 142         result = new RSAKeyPairRawCodec().encodePublicKey(this);
 143         break;
 144       case IKeyPairCodec.X509_FORMAT:
 145         result = new RSAKeyPairX509Codec().encodePublicKey(this);
 146         break;
 147       default:
 148         throw new IllegalArgumentException("Unsupported encoding format: "
 149                                            + format);
 150       }
 151     return result;
 152   }
 153
 154   /**
 155    * Returns <code>true</code> if the designated object is an instance of this
 156    * class and has the same RSA parameter values as this one.
 157    *
 158    * @param obj the other non-null RSA key to compare to.
 159    * @return <code>true</code> if the designated object is of the same type
 160    *         and value as this one.
 161    */
 162   public boolean equals(final Object obj)
 163   {
 164     if (obj == null)
 165       return false;
 166
 167     if (! (obj instanceof RSAPublicKey))
 168       return false;
 169
 170     final RSAPublicKey that = (RSAPublicKey) obj;
 171     return super.equals(that)
 172            && getPublicExponent().equals(that.getPublicExponent());
 173   }
 174
 175   public String toString()
 176   {
 177     if (str == null)
 178       {
 179         String ls = (String) AccessController.doPrivileged
 180             (new GetPropertyAction("line.separator"));
 181         str = new StringBuilder(this.getClass().getName()).append("(")
 182             .append(super.toString()).append(",").append(ls)
 183             .append(")")
 184             .toString();
 185       }
 186     return str;
 187   }
 188 }