libjava/classpath/gnu/java/security/key/dss/DSSKeyPairX509Codec.java

   1 /* DSSKeyPairX509Codec.java -- X.509 Encoding/Decoding handler
   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.java.security.key.dss;
  40
  41 import gnu.java.security.OID;
  42 import gnu.java.security.Registry;
  43 import gnu.java.security.der.BitString;
  44 import gnu.java.security.der.DER;
  45 import gnu.java.security.der.DERReader;
  46 import gnu.java.security.der.DERValue;
  47 import gnu.java.security.der.DERWriter;
  48 import gnu.java.security.key.IKeyPairCodec;
  49 import gnu.java.security.util.DerUtil;
  50
  51 import java.io.ByteArrayOutputStream;
  52 import java.io.IOException;
  53 import java.math.BigInteger;
  54 import java.security.InvalidParameterException;
  55 import java.security.PrivateKey;
  56 import java.security.PublicKey;
  57 import java.util.ArrayList;
  58
  59 /**
  60  * An implementation of an {@link IKeyPairCodec} that knows how to encode /
  61  * decode X.509 ASN.1 external representation of DSS public keys.
  62  */
  63 public class DSSKeyPairX509Codec
  64     implements IKeyPairCodec
  65 {
  66   private static final OID DSA_ALG_OID = new OID(Registry.DSA_OID_STRING);
  67
  68   // implicit 0-arguments constructor
  69
  70   public int getFormatID()
  71   {
  72     return X509_FORMAT;
  73   }
  74
  75   /**
  76    * Returns the X.509 ASN.1 <i>SubjectPublicKeyInfo</i> representation of a
  77    * DSA public key. The ASN.1 specification, as defined in RFC-3280, and
  78    * RFC-2459, is as follows:
  79    *
  80    * <pre>
  81    *   SubjectPublicKeyInfo ::= SEQUENCE {
  82    *     algorithm         AlgorithmIdentifier,
  83    *     subjectPublicKey  BIT STRING
  84    *   }
  85    *
  86    *   AlgorithmIdentifier ::= SEQUENCE {
  87    *     algorithm   OBJECT IDENTIFIER,
  88    *     parameters  ANY DEFINED BY algorithm OPTIONAL
  89    *   }
  90    *
  91    *   DssParams ::= SEQUENCE {
  92    *     p   INTEGER,
  93    *     q   INTEGER,
  94    *     g   INTEGER
  95    *   }
  96    * </pre>
  97    * <p>
  98    * Note that RFC-3280 (page 79) implies that some certificates MAY have an
  99    * absent, or NULL, parameters field in their AlgorithmIdentifier element,
 100    * implying that those parameters MUST be <i>inherited</i> from another
 101    * certificate. This implementation, encodes a <i>NULL</i> element as the DER
 102    * value of the parameters field when such is the case.
 103    * <p>
 104    * The <i>subjectPublicKey</i> field, which is a BIT STRING, contains the
 105    * DER-encoded form of the DSA public key as an INTEGER.
 106    *
 107    * <pre>
 108    *       DSAPublicKey ::= INTEGER -- public key, Y
 109    * </pre>
 110    *
 111    * @param key the {@link PublicKey} instance to encode. MUST be an instance of
 112    *          {@link DSSPublicKey}.
 113    * @return the ASN.1 representation of the <i>SubjectPublicKeyInfo</i> in an
 114    *         X.509 certificate.
 115    * @throw InvalidParameterException if <code>key</code> is not an instance
 116    *        of {@link DSSPublicKey} or if an exception occurs during the
 117    *        marshalling process.
 118    */
 119   public byte[] encodePublicKey(PublicKey key)
 120   {
 121     if (! (key instanceof DSSPublicKey))
 122       throw new InvalidParameterException("key");
 123
 124     DERValue derOID = new DERValue(DER.OBJECT_IDENTIFIER, DSA_ALG_OID);
 125
 126     DSSPublicKey dssKey = (DSSPublicKey) key;
 127     DERValue derParams;
 128     if (dssKey.hasInheritedParameters())
 129       derParams = new DERValue(DER.NULL, null);
 130     else
 131       {
 132         BigInteger p = dssKey.getParams().getP();
 133         BigInteger q = dssKey.getParams().getQ();
 134         BigInteger g = dssKey.getParams().getG();
 135
 136         DERValue derP = new DERValue(DER.INTEGER, p);
 137         DERValue derQ = new DERValue(DER.INTEGER, q);
 138         DERValue derG = new DERValue(DER.INTEGER, g);
 139
 140         ArrayList params = new ArrayList(3);
 141         params.add(derP);
 142         params.add(derQ);
 143         params.add(derG);
 144         derParams = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, params);
 145       }
 146
 147     ArrayList algorithmID = new ArrayList(2);
 148     algorithmID.add(derOID);
 149     algorithmID.add(derParams);
 150     DERValue derAlgorithmID = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE,
 151                                            algorithmID);
 152
 153     BigInteger y = dssKey.getY();
 154     DERValue derDSAPublicKey = new DERValue(DER.INTEGER, y);
 155     byte[] yBytes = derDSAPublicKey.getEncoded();
 156     DERValue derSPK = new DERValue(DER.BIT_STRING, new BitString(yBytes));
 157
 158     ArrayList spki = new ArrayList(2);
 159     spki.add(derAlgorithmID);
 160     spki.add(derSPK);
 161     DERValue derSPKI = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, spki);
 162
 163     byte[] result;
 164     ByteArrayOutputStream baos = new ByteArrayOutputStream();
 165     try
 166       {
 167         DERWriter.write(baos, derSPKI);
 168         result = baos.toByteArray();
 169       }
 170     catch (IOException x)
 171       {
 172         InvalidParameterException e = new InvalidParameterException(x.getMessage());
 173         e.initCause(x);
 174         throw e;
 175       }
 176     return result;
 177   }
 178
 179   /**
 180    * @throws InvalidParameterException ALWAYS.
 181    */
 182   public byte[] encodePrivateKey(PrivateKey key)
 183   {
 184     throw new InvalidParameterException("Wrong format for private keys");
 185   }
 186
 187   /**
 188    * @param input the byte array to unmarshall into a valid DSS
 189    *          {@link PublicKey} instance. MUST NOT be null.
 190    * @return a new instance of a {@link DSSPublicKey} decoded from the
 191    *         <i>SubjectPublicKeyInfo</i> material in an X.509 certificate.
 192    * @throw InvalidParameterException if an exception occurs during the
 193    *        unmarshalling process.
 194    */
 195   public PublicKey decodePublicKey(byte[] input)
 196   {
 197     if (input == null)
 198       throw new InvalidParameterException("Input bytes MUST NOT be null");
 199
 200     BigInteger p = null;
 201     BigInteger g = null;
 202     BigInteger q = null;
 203     BigInteger y;
 204     DERReader der = new DERReader(input);
 205     try
 206       {
 207         DERValue derSPKI = der.read();
 208         DerUtil.checkIsConstructed(derSPKI, "Wrong SubjectPublicKeyInfo field");
 209
 210         DERValue derAlgorithmID = der.read();
 211         DerUtil.checkIsConstructed(derAlgorithmID, "Wrong AlgorithmIdentifier field");
 212
 213         DERValue derOID = der.read();
 214         if (! (derOID.getValue() instanceof OID))
 215           throw new InvalidParameterException("Wrong Algorithm field");
 216
 217         OID algOID = (OID) derOID.getValue();
 218         if (! algOID.equals(DSA_ALG_OID))
 219           throw new InvalidParameterException("Unexpected OID: " + algOID);
 220
 221         DERValue val = der.read();
 222         // RFC-3280, page 79 states: "If the subjectPublicKeyInfo field of the
 223         // certificate contains an algorithm field with null parameters or
 224         // parameters are omitted, compare the certificate subjectPublicKey
 225         // algorithm to the working_public_key_algorithm.  If the certificate
 226         // subjectPublicKey algorithm and the working_public_key_algorithm are
 227         // different, set the working_public_key_parameters to null."
 228         // in other words, the parameters field of an AlgorithmIdentifier
 229         // element MAY NOT be present at all, or if present MAY be NULL!
 230         // the Mauve test ValidDSAParameterInheritenceTest5, in
 231         // gnu.testlet.java.security.cert.pkix.pkits, is/was failing because
 232         // of this.
 233         if (val.getTag() == DER.NULL)
 234           val = der.read();
 235         else if (val.isConstructed())
 236           {
 237             val = der.read();
 238             DerUtil.checkIsBigInteger(val, "Wrong P field");
 239             p = (BigInteger) val.getValue();
 240             val = der.read();
 241             DerUtil.checkIsBigInteger(val, "Wrong Q field");
 242             q = (BigInteger) val.getValue();
 243             val = der.read();
 244             DerUtil.checkIsBigInteger(val, "Wrong G field");
 245             g = (BigInteger) val.getValue();
 246
 247             val = der.read();
 248           }
 249
 250         if (! (val.getValue() instanceof BitString))
 251           throw new InvalidParameterException("Wrong SubjectPublicKey field");
 252
 253         byte[] yBytes = ((BitString) val.getValue()).toByteArray();
 254
 255         DERReader dsaPub = new DERReader(yBytes);
 256         val = dsaPub.read();
 257         DerUtil.checkIsBigInteger(val, "Wrong Y field");
 258         y = (BigInteger) val.getValue();
 259       }
 260     catch (IOException x)
 261       {
 262         InvalidParameterException e = new InvalidParameterException(x.getMessage());
 263         e.initCause(x);
 264         throw e;
 265       }
 266     return new DSSPublicKey(Registry.X509_ENCODING_ID, p, q, g, y);
 267   }
 268
 269   /**
 270    * @throws InvalidParameterException ALWAYS.
 271    */
 272   public PrivateKey decodePrivateKey(byte[] input)
 273   {
 274     throw new InvalidParameterException("Wrong format for private keys");
 275   }
 276 }