Source for gnu.java.security.key.rsa.GnuRSAPublicKey

   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: }