/*

 * Copyright (c) 1997, 2011, 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

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 */

package sun.security.provider;

import java.io.*;

import java.math.BigInteger;

import java.security.AlgorithmParametersSpi;

import java.security.spec.AlgorithmParameterSpec;

import java.security.spec.DSAParameterSpec;

import java.security.spec.InvalidParameterSpecException;

import sun.security.util.Debug;

import sun.security.util.DerValue;

import sun.security.util.DerOutputStream;

/**

 * This class implements the parameter set used by the

 * Digital Signature Algorithm as specified in the FIPS 186

 * standard.

 *

 * @author Jan Luehe

 *

 *

 * @since 1.2

 */

public class DSAParameters extends AlgorithmParametersSpi {

    // the prime (p)

    protected BigInteger p;

    // the sub-prime (q)

    protected BigInteger q;

    // the base (g)

    protected BigInteger g;

    protected void engineInit(AlgorithmParameterSpec paramSpec)

        throws InvalidParameterSpecException {

            if (!(paramSpec instanceof DSAParameterSpec)) {

                throw new InvalidParameterSpecException

                    ("Inappropriate parameter specification");

            }

            this.p = ((DSAParameterSpec)paramSpec).getP();

            this.q = ((DSAParameterSpec)paramSpec).getQ();

            this.g = ((DSAParameterSpec)paramSpec).getG();

    }

    protected void engineInit(byte[] params) throws IOException {

        DerValue encodedParams = new DerValue(params);

        if (encodedParams.tag != DerValue.tag_Sequence) {

            throw new IOException("DSA params parsing error");

        }

        encodedParams.data.reset();

        this.p = encodedParams.data.getBigInteger();

        this.q = encodedParams.data.getBigInteger();

        this.g = encodedParams.data.getBigInteger();

        if (encodedParams.data.available() != 0) {

            throw new IOException("encoded params have " +

                                  encodedParams.data.available() +

                                  " extra bytes");

        }

    }

    protected void engineInit(byte[] params, String decodingMethod)

        throws IOException {

            engineInit(params);

    }

    protected <T extends AlgorithmParameterSpec>

        T engineGetParameterSpec(Class<T> paramSpec)

        throws InvalidParameterSpecException

    {

            try {

                Class<?> dsaParamSpec = Class.forName

                    ("java.security.spec.DSAParameterSpec");

                if (dsaParamSpec.isAssignableFrom(paramSpec)) {

                    return paramSpec.cast(

                            new DSAParameterSpec(this.p, this.q, this.g));

                } else {

                    throw new InvalidParameterSpecException

                        ("Inappropriate parameter Specification");

                }

            } catch (ClassNotFoundException e) {

                throw new InvalidParameterSpecException

                    ("Unsupported parameter specification: " + e.getMessage());

            }

    }

    protected byte[] engineGetEncoded() throws IOException {

        DerOutputStream out = new DerOutputStream();

        DerOutputStream bytes = new DerOutputStream();

        bytes.putInteger(p);

        bytes.putInteger(q);

        bytes.putInteger(g);

        out.write(DerValue.tag_Sequence, bytes);

        return out.toByteArray();

    }

    protected byte[] engineGetEncoded(String encodingMethod)

        throws IOException {

            return engineGetEncoded();

    }

    /*

     * Returns a formatted string describing the parameters.

     */

    protected String engineToString() {

        return "\n\tp: " + Debug.toHexString(p)

            + "\n\tq: " + Debug.toHexString(q)

            + "\n\tg: " + Debug.toHexString(g)

            + "\n";

    }

}