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+/* SRPPublicKey.java --
+ Copyright (C) 2003, 2006 Free Software Foundation, Inc.
+
+This file is a part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at
+your option) any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
+USA
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package gnu.javax.crypto.key.srp6;
+
+import gnu.java.security.Registry;
+import gnu.java.security.key.IKeyPairCodec;
+
+import java.math.BigInteger;
+import java.security.PublicKey;
+
+/**
+ * <p>A representation of an SRP ephemeral public key.</p>
+ *
+ * <p>Reference:</p>
+ * <ol>
+ * <li><a href="http://srp.stanford.edu/design.html">SRP Protocol Design</a><br>
+ * Thomas J. Wu.</li>
+ * </ol>
+ */
+public class SRPPublicKey extends SRPKey implements PublicKey
+{
+
+ // Constants and variables
+ // -------------------------------------------------------------------------
+
+ /**
+ * The public exponent for either the server or the client engaged in the
+ * SRP protocol exchange.
+ */
+ private final BigInteger Y;
+
+ // Constructor(s)
+ // -------------------------------------------------------------------------
+
+ /**
+ * <p>Public constructor for use from outside this package.</p>
+ *
+ * @param N the public shared modulus.
+ * @param g the generator.
+ * @param Y the public exponent of the ephemeral key.
+ */
+ public SRPPublicKey(BigInteger N, BigInteger g, BigInteger Y)
+ {
+ super(N, g);
+
+ SRPAlgorithm.checkParams(N, g);
+ this.Y = Y;
+ }
+
+ /**
+ * <p>Default constructor. Assumes that N and g are already validated.</p>
+ *
+ * @param params an array of 3 values representing N, g and Y; the latter
+ * being the client's or server's public exponent.
+ */
+ SRPPublicKey(BigInteger[] params)
+ {
+ super(params[0], params[1]);
+
+ this.Y = params[2];
+ }
+
+ // Class methods
+ // -------------------------------------------------------------------------
+
+ /**
+ * <p>A class method that takes the output of the <code>encodePublicKey()</code>
+ * method of an SRP keypair codec object (an instance implementing
+ * {@link IKeyPairCodec} for SRP keys, and re-constructs an instance of this
+ * object.</p>
+ *
+ * @param k the contents of a previously encoded instance of this object.
+ * @throws ArrayIndexOutOfBoundsException if there is not enough bytes, in
+ * <code>k</code>, to represent a valid encoding of an instance of this object.
+ * @throws IllegalArgumentException if the byte sequence does not represent a
+ * valid encoding of an instance of this object.
+ */
+ public static SRPPublicKey valueOf(byte[] k)
+ {
+ // check magic...
+ // we should parse here enough bytes to know which codec to use, and
+ // direct the byte array to the appropriate codec. since we only have one
+ // codec, we could have immediately tried it; nevertheless since testing
+ // one byte is cheaper than instatiating a codec that will fail we test
+ // the first byte before we carry on.
+ if (k[0] == Registry.MAGIC_RAW_SRP_PUBLIC_KEY[0])
+ {
+ // it's likely to be in raw format. get a raw codec and hand it over
+ IKeyPairCodec codec = new SRPKeyPairRawCodec();
+ return (SRPPublicKey) codec.decodePublicKey(k);
+ }
+ else
+ {
+ throw new IllegalArgumentException("magic");
+ }
+ }
+
+ // Instance methods
+ // -------------------------------------------------------------------------
+
+ /**
+ * <p>Returns the public exponent of the key as a {@link BigInteger}.</p>
+ *
+ * @return the public exponent of the key as a {@link BigInteger}.
+ */
+ public BigInteger getY()
+ {
+ return Y;
+ }
+
+ // Other instance methods --------------------------------------------------
+
+ /**
+ * <p>Returns the encoded form of this public key according to the designated
+ * format.</p>
+ *
+ * @param format the desired format identifier of the resulting encoding.
+ * @return the byte sequence encoding this key according to the designated
+ * format.
+ * @throws IllegalArgumentException if the format is not supported.
+ */
+ public byte[] getEncoded(int format)
+ {
+ byte[] result;
+ switch (format)
+ {
+ case IKeyPairCodec.RAW_FORMAT:
+ result = new SRPKeyPairRawCodec().encodePublicKey(this);
+ break;
+ default:
+ throw new IllegalArgumentException("format");
+ }
+ return result;
+ }
+
+ /**
+ * <p>Returns <code>true</code> if the designated object is an instance of
+ * <code>SRPPublicKey</code>and has the same SRP parameter values as this one.
+ * </p>
+ *
+ * @param obj the other non-null SRP key to compare to.
+ * @return <code>true</code> if the designated object is of the same type and
+ * value as this one.
+ */
+ public boolean equals(Object obj)
+ {
+ if (obj == null)
+ {
+ return false;
+ }
+ if (!(obj instanceof SRPPublicKey))
+ {
+ return false;
+ }
+ SRPPublicKey that = (SRPPublicKey) obj;
+ return super.equals(that) && Y.equals(that.getY());
+ }
+}