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	/*
	* Copyright (c) 2018, 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 sun.security.rsa;

	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 java.security.spec.PSSParameterSpec;
	import static java.security.spec.PSSParameterSpec.DEFAULT;

	/**
	* This class implements the PSS parameters used with the RSA
	* signatures in PSS padding. Here is its ASN.1 definition:
	* RSASSA-PSS-params ::= SEQUENCE {
	* hashAlgorithm [0] HashAlgorithm DEFAULT sha1,
	* maskGenAlgorithm [1] MaskGenAlgorithm DEFAULT mgf1SHA1,
	* saltLength [2] INTEGER DEFAULT 20
	* trailerField [3] TrailerField DEFAULT trailerFieldBC
	* }
	*
	* @author Valerie Peng
	*
	*/

	public final class PSSParameters extends AlgorithmParametersSpi {

	private PSSParameterSpec spec;

	public PSSParameters() {
	}

	@Override
	protected void engineInit(AlgorithmParameterSpec paramSpec)
	throws InvalidParameterSpecException {
	if (!(paramSpec instanceof PSSParameterSpec)) {
	throw new InvalidParameterSpecException
	("Inappropriate parameter specification");
	}
	PSSParameterSpec spec = (PSSParameterSpec) paramSpec;

	String mgfName = spec.getMGFAlgorithm();
	if (!spec.getMGFAlgorithm().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.spec = spec;
	}

	@Override
	protected void engineInit(byte[] encoded) throws IOException {
	// first initialize with the DEFAULT values before
	// retrieving from the encoding bytes
	String mdName = DEFAULT.getDigestAlgorithm();
	MGF1ParameterSpec mgfSpec = (MGF1ParameterSpec) DEFAULT.getMGFParameters();
	int saltLength = DEFAULT.getSaltLength();
	int trailerField = DEFAULT.getTrailerField();

	DerInputStream der = new DerInputStream(encoded);
	DerValue[] datum = der.getSequence(4);

	for (DerValue d : datum) {
	if (d.isContextSpecific((byte) 0x00)) {
	// hash algid
	mdName = AlgorithmId.parse
	(d.data.getDerValue()).getName();
	} else if (d.isContextSpecific((byte) 0x01)) {
	// mgf algid
	AlgorithmId val = AlgorithmId.parse(d.data.getDerValue());
	if (!val.getOID().equals(AlgorithmId.mgf1_oid)) {
	throw new IOException("Only MGF1 mgf is supported");
	}
	AlgorithmId params = AlgorithmId.parse(
	new DerValue(val.getEncodedParams()));
	String mgfDigestName = params.getName();
	switch (mgfDigestName) {
	case "SHA-1":
	mgfSpec = MGF1ParameterSpec.SHA1;
	break;
	case "SHA-224":
	mgfSpec = MGF1ParameterSpec.SHA224;
	break;
	case "SHA-256":
	mgfSpec = MGF1ParameterSpec.SHA256;
	break;
	case "SHA-384":
	mgfSpec = MGF1ParameterSpec.SHA384;
	break;
	case "SHA-512":
	mgfSpec = MGF1ParameterSpec.SHA512;
	break;
	case "SHA-512/224":
	mgfSpec = MGF1ParameterSpec.SHA512_224;
	break;
	case "SHA-512/256":
	mgfSpec = MGF1ParameterSpec.SHA512_256;
	break;
	default:
	throw new IOException
	("Unrecognized message digest algorithm " +
	mgfDigestName);
	}
	} else if (d.isContextSpecific((byte) 0x02)) {
	// salt length
	saltLength = d.data.getDerValue().getInteger();
	if (saltLength < 0) {
	throw new IOException("Negative value for saltLength");
	}
	} else if (d.isContextSpecific((byte) 0x03)) {
	// trailer field
	trailerField = d.data.getDerValue().getInteger();
	if (trailerField != 1) {
	throw new IOException("Unsupported trailerField value " +
	trailerField);
	}
	} else {
	throw new IOException("Invalid encoded PSSParameters");
	}
	}

	this.spec = new PSSParameterSpec(mdName, "MGF1", mgfSpec,
	saltLength, trailerField);
	}

	@Override
	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);
	}

	@Override
	protected <T extends AlgorithmParameterSpec>
	T engineGetParameterSpec(Class<T> paramSpec)
	throws InvalidParameterSpecException {
	if (PSSParameterSpec.class.isAssignableFrom(paramSpec)) {
	return paramSpec.cast(spec);
	} else {
	throw new InvalidParameterSpecException
	("Inappropriate parameter specification");
	}
	}

	@Override
	protected byte[] engineGetEncoded() throws IOException {
	return getEncoded(spec);
	}

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

	@Override
	protected String engineToString() {
	return spec.toString();
	}

	/**
	* Returns the encoding of a {@link PSSParameterSpec} object. This method
	* is used in this class and {@link AlgorithmId}.
	*
	* @param spec a {@code PSSParameterSpec} object
	* @return its DER encoding
	* @throws IOException if the name of a MessageDigest or MaskGenAlgorithm
	* is unsupported
	*/
	public static byte[] getEncoded(PSSParameterSpec spec) throws IOException {

	AlgorithmParameterSpec mgfSpec = spec.getMGFParameters();
	if (!(mgfSpec instanceof MGF1ParameterSpec)) {
	throw new IOException("Cannot encode " + mgfSpec);
	}

	MGF1ParameterSpec mgf1Spec = (MGF1ParameterSpec)mgfSpec;

	DerOutputStream tmp = new DerOutputStream();
	DerOutputStream tmp2, tmp3;

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

	// MGF
	AlgorithmId mgfDigestId;
	try {
	mgfDigestId = AlgorithmId.get(mgf1Spec.getDigestAlgorithm());
	} catch (NoSuchAlgorithmException nase) {
	throw new IOException("AlgorithmId " +
	mgf1Spec.getDigestAlgorithm() + " impl not found");
	}

	if (!mgfDigestId.getOID().equals(AlgorithmId.SHA_oid)) {
	tmp2 = new DerOutputStream();
	tmp2.putOID(AlgorithmId.mgf1_oid);
	mgfDigestId.encode(tmp2);
	tmp3 = new DerOutputStream();
	tmp3.write(DerValue.tag_Sequence, tmp2);
	tmp.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte) 1),
	tmp3);
	}

	// SaltLength
	if (spec.getSaltLength() != 20) {
	tmp2 = new DerOutputStream();
	tmp2.putInteger(spec.getSaltLength());
	tmp.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte) 2),
	tmp2);
	}

	// TrailerField
	if (spec.getTrailerField() != PSSParameterSpec.TRAILER_FIELD_BC) {
	tmp2 = new DerOutputStream();
	tmp2.putInteger(spec.getTrailerField());
	tmp.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte) 3),
	tmp2);
	}

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

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