libjava/classpath/gnu/javax/crypto/key/dh/DHKeyPairX509Codec.java

   1 /* DHKeyPairX509Codec.java -- X.509 DER encoder/decoder for DH keys
   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.key.dh;
  40
  41 import java.io.ByteArrayOutputStream;
  42 import java.io.IOException;
  43 import java.math.BigInteger;
  44 import java.security.InvalidParameterException;
  45 import java.security.PrivateKey;
  46 import java.security.PublicKey;
  47 import java.util.ArrayList;
  48
  49 import gnu.java.security.OID;
  50 import gnu.java.security.Registry;
  51 import gnu.java.security.der.BitString;
  52 import gnu.java.security.der.DER;
  53 import gnu.java.security.der.DERReader;
  54 import gnu.java.security.der.DERValue;
  55 import gnu.java.security.der.DERWriter;
  56 import gnu.java.security.key.IKeyPairCodec;
  57 import gnu.java.security.util.DerUtil;
  58
  59 public class DHKeyPairX509Codec
  60     implements IKeyPairCodec
  61 {
  62   private static final OID DH_ALG_OID = new OID(Registry.DH_OID_STRING);
  63
  64   // implicit 0-arguments constructor
  65
  66   public int getFormatID()
  67   {
  68     return X509_FORMAT;
  69   }
  70
  71   /**
  72    * Returns the DER-encoded form of the X.509 ASN.1 <i>SubjectPublicKeyInfo</i>
  73    * representation of a DH public key. The ASN.1 specification, as defined in
  74    * RFC-3280, and RFC-2459, is as follows:
  75    *
  76    * <pre>
  77    *   SubjectPublicKeyInfo ::= SEQUENCE {
  78    *     algorithm         AlgorithmIdentifier,
  79    *     subjectPublicKey  BIT STRING
  80    *   }
  81    *
  82    *   AlgorithmIdentifier ::= SEQUENCE {
  83    *     algorithm   OBJECT IDENTIFIER,
  84    *     parameters  ANY DEFINED BY algorithm OPTIONAL
  85    *   }
  86    *
  87    *   DhParams ::= SEQUENCE {
  88    *     p  INTEGER, -- odd prime, p=jq +1
  89    *     g  INTEGER, -- generator, g
  90    *     q  INTEGER  -- factor of p-1
  91    *   }
  92    * </pre>
  93    *
  94    * <p>The <i>subjectPublicKey</i> field, which is a BIT STRING, contains the
  95    * DER-encoded form of the DH public key as an INTEGER.</p>
  96    *
  97    * <pre>
  98    *       DHPublicKey ::= INTEGER -- public key, y = g^x mod p
  99    * </pre>
 100    *
 101    * @param key the {@link PublicKey} instance to encode. MUST be an instance of
 102    *          {@link GnuDHPublicKey}.
 103    * @return the DER-encoded form of the ASN.1 representation of the
 104    *         <i>SubjectPublicKeyInfo</i> in an X.509 certificate.
 105    * @throw InvalidParameterException if <code>key</code> is not an instance
 106    *        of {@link GnuDHPublicKey} or if an exception occurs during the
 107    *        marshalling process.
 108    */
 109   public byte[] encodePublicKey(PublicKey key)
 110   {
 111     if (! (key instanceof GnuDHPublicKey))
 112       throw new InvalidParameterException("Wrong key type");
 113
 114     DERValue derOID = new DERValue(DER.OBJECT_IDENTIFIER, DH_ALG_OID);
 115
 116     GnuDHPublicKey dhKey = (GnuDHPublicKey) key;
 117     BigInteger p = dhKey.getParams().getP();
 118     BigInteger g = dhKey.getParams().getG();
 119     BigInteger q = dhKey.getQ();
 120     BigInteger y = dhKey.getY();
 121
 122     DERValue derP = new DERValue(DER.INTEGER, p);
 123     DERValue derG = new DERValue(DER.INTEGER, g);
 124     DERValue derQ = new DERValue(DER.INTEGER, q);
 125
 126     ArrayList params = new ArrayList(3);
 127     params.add(derP);
 128     params.add(derG);
 129     params.add(derQ);
 130     DERValue derParams = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, params);
 131
 132     ArrayList algorithmID = new ArrayList(2);
 133     algorithmID.add(derOID);
 134     algorithmID.add(derParams);
 135     DERValue derAlgorithmID = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE,
 136                                            algorithmID);
 137
 138     DERValue derDHPublicKey = new DERValue(DER.INTEGER, y);
 139     byte[] yBytes = derDHPublicKey.getEncoded();
 140     DERValue derSPK = new DERValue(DER.BIT_STRING, new BitString(yBytes));
 141
 142     ArrayList spki = new ArrayList(2);
 143     spki.add(derAlgorithmID);
 144     spki.add(derSPK);
 145     DERValue derSPKI = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, spki);
 146
 147     byte[] result;
 148     ByteArrayOutputStream baos = new ByteArrayOutputStream();
 149     try
 150       {
 151         DERWriter.write(baos, derSPKI);
 152         result = baos.toByteArray();
 153       }
 154     catch (IOException x)
 155       {
 156         InvalidParameterException e = new InvalidParameterException();
 157         e.initCause(x);
 158         throw e;
 159       }
 160
 161     return result;
 162   }
 163
 164   /**
 165    * @throws InvalidParameterException ALWAYS.
 166    */
 167   public byte[] encodePrivateKey(PrivateKey key)
 168   {
 169     throw new InvalidParameterException("Wrong format for private keys");
 170   }
 171
 172   /**
 173    * @param input the byte array to unmarshall into a valid DH
 174    *          {@link PublicKey} instance. MUST NOT be null.
 175    * @return a new instance of a {@link GnuDHPublicKey} decoded from the
 176    *         <i>SubjectPublicKeyInfo</i> material in an X.509 certificate.
 177    * @throw InvalidParameterException if an exception occurs during the
 178    *        unmarshalling process.
 179    */
 180   public PublicKey decodePublicKey(byte[] input)
 181   {
 182     if (input == null)
 183       throw new InvalidParameterException("Input bytes MUST NOT be null");
 184
 185     BigInteger p, g, q, y;
 186     DERReader der = new DERReader(input);
 187     try
 188       {
 189         DERValue derSPKI = der.read();
 190         DerUtil.checkIsConstructed(derSPKI, "Wrong SubjectPublicKeyInfo field");
 191
 192         DERValue derAlgorithmID = der.read();
 193         DerUtil.checkIsConstructed(derAlgorithmID, "Wrong AlgorithmIdentifier field");
 194
 195         DERValue derOID = der.read();
 196         if (! (derOID.getValue() instanceof OID))
 197           throw new InvalidParameterException("Wrong Algorithm field");
 198
 199         OID algOID = (OID) derOID.getValue();
 200         if (! algOID.equals(DH_ALG_OID))
 201           throw new InvalidParameterException("Unexpected OID: " + algOID);
 202
 203         DERValue derParams = der.read();
 204         DerUtil.checkIsConstructed(derParams, "Wrong DH Parameters field");
 205
 206         DERValue val = der.read();
 207         DerUtil.checkIsBigInteger(val, "Wrong P field");
 208         p = (BigInteger) val.getValue();
 209         val = der.read();
 210         DerUtil.checkIsBigInteger(val, "Wrong G field");
 211         g = (BigInteger) val.getValue();
 212         val = der.read();
 213         DerUtil.checkIsBigInteger(val, "Wrong Q field");
 214         q = (BigInteger) val.getValue();
 215
 216         val = der.read();
 217         if (! (val.getValue() instanceof BitString))
 218           throw new InvalidParameterException("Wrong SubjectPublicKey field");
 219
 220         byte[] yBytes = ((BitString) val.getValue()).toByteArray();
 221
 222         DERReader dhPub = new DERReader(yBytes);
 223         val = dhPub.read();
 224         DerUtil.checkIsBigInteger(val, "Wrong Y field");
 225         y = (BigInteger) val.getValue();
 226       }
 227     catch (IOException x)
 228       {
 229         InvalidParameterException e = new InvalidParameterException();
 230         e.initCause(x);
 231         throw e;
 232       }
 233
 234     return new GnuDHPublicKey(Registry.X509_ENCODING_ID, q, p, g, y);
 235   }
 236
 237   /**
 238    * @throws InvalidParameterException ALWAYS.
 239    */
 240   public PrivateKey decodePrivateKey(byte[] input)
 241   {
 242     throw new InvalidParameterException("Wrong format for private keys");
 243   }
 244 }