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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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

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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;

    private static ObjectIdentifier OID_PSpecified;

    static {

        try {

            OID_MGF1 = new ObjectIdentifier(new int[] {1,2,840,113549,1,1,8});

        } catch (IOException ioe) {

            // should not happen

            OID_MGF1 = null;

        }

        try {

            OID_PSpecified =

                new ObjectIdentifier(new int[] {1,2,840,113549,1,1,9});

        } catch (IOException ioe) {

            // should not happen

            OID_PSpecified = null;

        }

    }

    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");

        }

    }

    private static String convertToStandardName(String internalName) {

        if (internalName.equals("SHA")) {

            return "SHA-1";

        } else if (internalName.equals("SHA256")) {

            return "SHA-256";

        } else if (internalName.equals("SHA384")) {

            return "SHA-384";

        } else if (internalName.equals("SHA512")) {

            return "SHA-512";

        } else {

            return internalName;

        }

    }

    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 = convertToStandardName(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((Object) OID_MGF1)) {

                    throw new IOException("Only MGF1 mgf is supported");

                }

                AlgorithmId params = AlgorithmId.parse(

                    new DerValue(val.getEncodedParams()));

                String mgfDigestName = convertToStandardName(params.getName());

                if (mgfDigestName.equals("SHA-1")) {

                    mgfSpec = MGF1ParameterSpec.SHA1;

                } 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 {

                    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((Object) 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() {

        StringBuffer sb = new StringBuffer();

        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();

    }

}