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	/*
	* Copyright (c) 2003, 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.math.BigInteger;
	import java.io.*;
	import sun.security.util.*;
	import sun.security.x509.*;
	import java.security.AlgorithmParametersSpi;
	import java.security.NoSuchAlgorithmException;
	import java.security.spec.AlgorithmParameterSpec;
	import java.security.spec.InvalidParameterSpecException;
	import java.security.spec.MGF1ParameterSpec;
	import javax.crypto.spec.PSource;
	import javax.crypto.spec.OAEPParameterSpec;

	/**
	* This class implements the OAEP parameters used with the RSA
	* algorithm in OAEP padding. Here is its ASN.1 definition:
	* RSAES-OAEP-params ::= SEQUENCE {
	* hashAlgorithm [0] HashAlgorithm DEFAULT sha1,
	* maskGenAlgorithm [1] MaskGenAlgorithm DEFAULT mgf1SHA1,
	* pSourceAlgorithm [2] PSourceAlgorithm DEFAULT pSpecifiedEmpty
	* }
	*
	* @author Valerie Peng
	*
	*/

	public final class OAEPParameters extends AlgorithmParametersSpi {

	private String mdName;
	private MGF1ParameterSpec mgfSpec;
	private byte[] p;
	private static ObjectIdentifier OID_MGF1 =
	ObjectIdentifier.of(KnownOIDs.MGF1);
	private static ObjectIdentifier OID_PSpecified =
	ObjectIdentifier.of(KnownOIDs.PSpecified);

	public OAEPParameters() {
	}

	protected void engineInit(AlgorithmParameterSpec paramSpec)
	throws InvalidParameterSpecException {
	if (!(paramSpec instanceof OAEPParameterSpec)) {
	throw new InvalidParameterSpecException
	("Inappropriate parameter specification");
	}
	OAEPParameterSpec spec = (OAEPParameterSpec) paramSpec;
	mdName = spec.getDigestAlgorithm();
	String mgfName = spec.getMGFAlgorithm();
	if (!mgfName.equalsIgnoreCase("MGF1")) {
	throw new InvalidParameterSpecException("Unsupported mgf " +
	mgfName + "; MGF1 only");
	}
	AlgorithmParameterSpec mgfSpec = spec.getMGFParameters();
	if (!(mgfSpec instanceof MGF1ParameterSpec)) {
	throw new InvalidParameterSpecException("Inappropriate mgf " +
	"parameters; non-null MGF1ParameterSpec only");
	}
	this.mgfSpec = (MGF1ParameterSpec) mgfSpec;
	PSource pSrc = spec.getPSource();
	if (pSrc.getAlgorithm().equals("PSpecified")) {
	p = ((PSource.PSpecified) pSrc).getValue();
	} else {
	throw new InvalidParameterSpecException("Unsupported pSource " +
	pSrc.getAlgorithm() + "; PSpecified only");
	}
	}

	protected void engineInit(byte[] encoded)
	throws IOException {
	DerInputStream der = new DerInputStream(encoded);
	mdName = "SHA-1";
	mgfSpec = MGF1ParameterSpec.SHA1;
	p = new byte[0];
	DerValue[] datum = der.getSequence(3);
	for (int i=0; i<datum.length; i++) {
	DerValue data = datum[i];
	if (data.isContextSpecific((byte) 0x00)) {
	// hash algid
	mdName = AlgorithmId.parse
	(data.data.getDerValue()).getName();
	} else if (data.isContextSpecific((byte) 0x01)) {
	// mgf algid
	AlgorithmId val = AlgorithmId.parse(data.data.getDerValue());
	if (!val.getOID().equals(OID_MGF1)) {
	throw new IOException("Only MGF1 mgf is supported");
	}
	AlgorithmId params = AlgorithmId.parse(
	new DerValue(val.getEncodedParams()));
	String mgfDigestName = params.getName();
	if (mgfDigestName.equals("SHA-1")) {
	mgfSpec = MGF1ParameterSpec.SHA1;
	} else if (mgfDigestName.equals("SHA-224")) {
	mgfSpec = MGF1ParameterSpec.SHA224;
	} else if (mgfDigestName.equals("SHA-256")) {
	mgfSpec = MGF1ParameterSpec.SHA256;
	} else if (mgfDigestName.equals("SHA-384")) {
	mgfSpec = MGF1ParameterSpec.SHA384;
	} else if (mgfDigestName.equals("SHA-512")) {
	mgfSpec = MGF1ParameterSpec.SHA512;
	} else if (mgfDigestName.equals("SHA-512/224")) {
	mgfSpec = MGF1ParameterSpec.SHA512_224;
	} else if (mgfDigestName.equals("SHA-512/256")) {
	mgfSpec = MGF1ParameterSpec.SHA512_256;
	} else {
	throw new IOException(
	"Unrecognized message digest algorithm");
	}
	} else if (data.isContextSpecific((byte) 0x02)) {
	// pSource algid
	AlgorithmId val = AlgorithmId.parse(data.data.getDerValue());
	if (!val.getOID().equals(OID_PSpecified)) {
	throw new IOException("Wrong OID for pSpecified");
	}
	DerInputStream dis = new DerInputStream(val.getEncodedParams());
	p = dis.getOctetString();
	if (dis.available() != 0) {
	throw new IOException("Extra data for pSpecified");
	}
	} else {
	throw new IOException("Invalid encoded OAEPParameters");
	}
	}
	}

	protected void engineInit(byte[] encoded, String decodingMethod)
	throws IOException {
	if ((decodingMethod != null) &&
	(!decodingMethod.equalsIgnoreCase("ASN.1"))) {
	throw new IllegalArgumentException("Only support ASN.1 format");
	}
	engineInit(encoded);
	}

	protected <T extends AlgorithmParameterSpec>
	T engineGetParameterSpec(Class<T> paramSpec)
	throws InvalidParameterSpecException {
	if (OAEPParameterSpec.class.isAssignableFrom(paramSpec)) {
	return paramSpec.cast(
	new OAEPParameterSpec(mdName, "MGF1", mgfSpec,
	new PSource.PSpecified(p)));
	} else {
	throw new InvalidParameterSpecException
	("Inappropriate parameter specification");
	}
	}

	protected byte[] engineGetEncoded() throws IOException {
	DerOutputStream tmp = new DerOutputStream();
	DerOutputStream tmp2, tmp3;

	// MD
	AlgorithmId mdAlgId;
	try {
	mdAlgId = AlgorithmId.get(mdName);
	} catch (NoSuchAlgorithmException nsae) {
	throw new IOException("AlgorithmId " + mdName +
	" impl not found");
	}
	tmp2 = new DerOutputStream();
	mdAlgId.derEncode(tmp2);
	tmp.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte)0),
	tmp2);

	// MGF
	tmp2 = new DerOutputStream();
	tmp2.putOID(OID_MGF1);
	AlgorithmId mgfDigestId;
	try {
	mgfDigestId = AlgorithmId.get(mgfSpec.getDigestAlgorithm());
	} catch (NoSuchAlgorithmException nase) {
	throw new IOException("AlgorithmId " +
	mgfSpec.getDigestAlgorithm() + " impl not found");
	}
	mgfDigestId.encode(tmp2);
	tmp3 = new DerOutputStream();
	tmp3.write(DerValue.tag_Sequence, tmp2);
	tmp.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte)1),
	tmp3);

	// PSource
	tmp2 = new DerOutputStream();
	tmp2.putOID(OID_PSpecified);
	tmp2.putOctetString(p);
	tmp3 = new DerOutputStream();
	tmp3.write(DerValue.tag_Sequence, tmp2);
	tmp.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte)2),
	tmp3);

	// Put all together under a SEQUENCE tag
	DerOutputStream out = new DerOutputStream();
	out.write(DerValue.tag_Sequence, tmp);
	return out.toByteArray();
	}

	protected byte[] engineGetEncoded(String encodingMethod)
	throws IOException {
	if ((encodingMethod != null) &&
	(!encodingMethod.equalsIgnoreCase("ASN.1"))) {
	throw new IllegalArgumentException("Only support ASN.1 format");
	}
	return engineGetEncoded();
	}

	protected String engineToString() {
	StringBuilder sb = new StringBuilder();
	sb.append("MD: " + mdName + "\n");
	sb.append("MGF: MGF1" + mgfSpec.getDigestAlgorithm() + "\n");
	sb.append("PSource: PSpecified " +
	(p.length==0? "":Debug.toHexString(new BigInteger(p))) + "\n");
	return sb.toString();
	}
	}

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