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	/*
	* Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package com.sun.crypto.provider;

	import java.io.*;
	import java.util.Objects;
	import java.math.BigInteger;
	import java.security.KeyRep;
	import java.security.InvalidKeyException;
	import java.security.ProviderException;
	import java.security.PublicKey;
	import javax.crypto.spec.DHParameterSpec;
	import sun.security.util.*;


	/**
	* A public key in X.509 format for the Diffie-Hellman key agreement algorithm.
	*
	* @author Jan Luehe
	*
	*
	* @see DHPrivateKey
	* @see javax.crypto.KeyAgreement
	*/
	final class DHPublicKey implements PublicKey,
	javax.crypto.interfaces.DHPublicKey, Serializable {

	@java.io.Serial
	static final long serialVersionUID = 7647557958927458271L;

	// the public key
	private BigInteger y;

	// the key bytes, without the algorithm information
	private byte[] key;

	// the encoded key
	private byte[] encodedKey;

	// the prime modulus
	private BigInteger p;

	// the base generator
	private BigInteger g;

	// the private-value length (optional)
	private int l;

	// Note: this OID is used by DHPrivateKey as well.
	static ObjectIdentifier DH_OID =
	ObjectIdentifier.of(KnownOIDs.DiffieHellman);

	/**
	* Make a DH public key out of a public value <code>y</code>, a prime
	* modulus <code>p</code>, and a base generator <code>g</code>.
	*
	* @param y the public value
	* @param p the prime modulus
	* @param g the base generator
	*
	* @exception InvalidKeyException if the key cannot be encoded
	*/
	DHPublicKey(BigInteger y, BigInteger p, BigInteger g)
	throws InvalidKeyException {
	this(y, p, g, 0);
	}

	/**
	* Make a DH public key out of a public value <code>y</code>, a prime
	* modulus <code>p</code>, a base generator <code>g</code>, and a
	* private-value length <code>l</code>.
	*
	* @param y the public value
	* @param p the prime modulus
	* @param g the base generator
	* @param l the private-value length
	*
	* @exception ProviderException if the key cannot be encoded
	*/
	DHPublicKey(BigInteger y, BigInteger p, BigInteger g, int l) {
	this.y = y;
	this.p = p;
	this.g = g;
	this.l = l;
	try {
	this.key = new DerValue(DerValue.tag_Integer,
	this.y.toByteArray()).toByteArray();
	this.encodedKey = getEncoded();
	} catch (IOException e) {
	throw new ProviderException("Cannot produce ASN.1 encoding", e);
	}
	}

	/**
	* Make a DH public key from its DER encoding (X.509).
	*
	* @param encodedKey the encoded key
	*
	* @exception InvalidKeyException if the encoded key does not represent
	* a Diffie-Hellman public key
	*/
	DHPublicKey(byte[] encodedKey) throws InvalidKeyException {
	InputStream inStream = new ByteArrayInputStream(encodedKey);
	try {
	DerValue derKeyVal = new DerValue(inStream);
	if (derKeyVal.tag != DerValue.tag_Sequence) {
	throw new InvalidKeyException ("Invalid key format");
	}

	/*
	* Parse the algorithm identifier
	*/
	DerValue algid = derKeyVal.data.getDerValue();
	if (algid.tag != DerValue.tag_Sequence) {
	throw new InvalidKeyException("AlgId is not a SEQUENCE");
	}
	DerInputStream derInStream = algid.toDerInputStream();
	ObjectIdentifier oid = derInStream.getOID();
	if (oid == null) {
	throw new InvalidKeyException("Null OID");
	}
	if (derInStream.available() == 0) {
	throw new InvalidKeyException("Parameters missing");
	}

	/*
	* Parse the parameters
	*/
	DerValue params = derInStream.getDerValue();
	if (params.tag == DerValue.tag_Null) {
	throw new InvalidKeyException("Null parameters");
	}
	if (params.tag != DerValue.tag_Sequence) {
	throw new InvalidKeyException("Parameters not a SEQUENCE");
	}
	params.data.reset();
	this.p = params.data.getBigInteger();
	this.g = params.data.getBigInteger();
	// Private-value length is OPTIONAL
	if (params.data.available() != 0) {
	this.l = params.data.getInteger();
	}
	if (params.data.available() != 0) {
	throw new InvalidKeyException("Extra parameter data");
	}

	/*
	* Parse the key
	*/
	this.key = derKeyVal.data.getBitString();
	parseKeyBits();
	if (derKeyVal.data.available() != 0) {
	throw new InvalidKeyException("Excess key data");
	}

	this.encodedKey = encodedKey.clone();
	} catch (IOException \| NumberFormatException e) {
	throw new InvalidKeyException("Error parsing key encoding", e);
	}
	}

	/**
	* Returns the encoding format of this key: "X.509"
	*/
	public String getFormat() {
	return "X.509";
	}

	/**
	* Returns the name of the algorithm associated with this key: "DH"
	*/
	public String getAlgorithm() {
	return "DH";
	}

	/**
	* Get the encoding of the key.
	*/
	public synchronized byte[] getEncoded() {
	if (this.encodedKey == null) {
	try {
	DerOutputStream algid = new DerOutputStream();

	// store oid in algid
	algid.putOID(DH_OID);

	// encode parameters
	DerOutputStream params = new DerOutputStream();
	params.putInteger(this.p);
	params.putInteger(this.g);
	if (this.l != 0) {
	params.putInteger(this.l);
	}
	// wrap parameters into SEQUENCE
	DerValue paramSequence = new DerValue(DerValue.tag_Sequence,
	params.toByteArray());
	// store parameter SEQUENCE in algid
	algid.putDerValue(paramSequence);

	// wrap algid into SEQUENCE, and store it in key encoding
	DerOutputStream tmpDerKey = new DerOutputStream();
	tmpDerKey.write(DerValue.tag_Sequence, algid);

	// store key data
	tmpDerKey.putBitString(this.key);

	// wrap algid and key into SEQUENCE
	DerOutputStream derKey = new DerOutputStream();
	derKey.write(DerValue.tag_Sequence, tmpDerKey);
	this.encodedKey = derKey.toByteArray();
	} catch (IOException e) {
	return null;
	}
	}
	return this.encodedKey.clone();
	}

	/**
	* Returns the public value, <code>y</code>.
	*
	* @return the public value, <code>y</code>
	*/
	public BigInteger getY() {
	return this.y;
	}

	/**
	* Returns the key parameters.
	*
	* @return the key parameters
	*/
	public DHParameterSpec getParams() {
	if (this.l != 0) {
	return new DHParameterSpec(this.p, this.g, this.l);
	} else {
	return new DHParameterSpec(this.p, this.g);
	}
	}

	public String toString() {
	String LINE_SEP = System.lineSeparator();

	StringBuilder sb
	= new StringBuilder("SunJCE Diffie-Hellman Public Key:"
	+ LINE_SEP + "y:" + LINE_SEP
	+ Debug.toHexString(this.y)
	+ LINE_SEP + "p:" + LINE_SEP
	+ Debug.toHexString(this.p)
	+ LINE_SEP + "g:" + LINE_SEP
	+ Debug.toHexString(this.g));
	if (this.l != 0)
	sb.append(LINE_SEP + "l:" + LINE_SEP + " " + this.l);
	return sb.toString();
	}

	private void parseKeyBits() throws InvalidKeyException {
	try {
	DerInputStream in = new DerInputStream(this.key);
	this.y = in.getBigInteger();
	} catch (IOException e) {
	throw new InvalidKeyException(
	"Error parsing key encoding: " + e.toString());
	}
	}

	/**
	* Calculates a hash code value for the object.
	* Objects that are equal will also have the same hashcode.
	*/
	public int hashCode() {
	return Objects.hash(y, p, g);
	}

	public boolean equals(Object obj) {
	if (this == obj) return true;

	if (!(obj instanceof javax.crypto.interfaces.DHPublicKey)) {
	return false;
	}

	javax.crypto.interfaces.DHPublicKey other =
	(javax.crypto.interfaces.DHPublicKey) obj;
	DHParameterSpec otherParams = other.getParams();
	return ((this.y.compareTo(other.getY()) == 0) &&
	(this.p.compareTo(otherParams.getP()) == 0) &&
	(this.g.compareTo(otherParams.getG()) == 0));
	}

	/**
	* Replace the DH public key to be serialized.
	*
	* @return the standard KeyRep object to be serialized
	*
	* @throws java.io.ObjectStreamException if a new object representing
	* this DH public key could not be created
	*/
	@java.io.Serial
	private Object writeReplace() throws java.io.ObjectStreamException {
	return new KeyRep(KeyRep.Type.PUBLIC,
	getAlgorithm(),
	getFormat(),
	getEncoded());
	}
	}

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