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

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 * 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,

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package sun.security.ec;

import java.io.IOException;

import java.math.BigInteger;

import java.security.spec.AlgorithmParameterSpec;

import java.security.spec.NamedParameterSpec;

import java.util.Collections;

import java.util.Map;

import java.util.HashMap;

import java.util.Optional;

import java.util.function.Function;

import java.util.function.Supplier;

import sun.security.util.ObjectIdentifier;

import sun.security.x509.AlgorithmId;

public class XECParameters {

    // Naming/identification parameters

    private final ObjectIdentifier oid;

    private final String name;

    // Curve/field parameters

    private final int bits;

    private final BigInteger p;

    private final int logCofactor;

    private final int a24;

    private final byte basePoint;

    /**

     *

     * Construct an object holding the supplied parameters. No parameters are

     * checked, so this method always succeeds. This method supports

     * Montgomery curves of the form y^2 = x^3 + ax^2 + x.

     *

     * @param bits The number of relevant bits in a public/private key.

     * @param p The prime that defines the finite field.

     * @param a24 The value of (a - 2) / 4, where a is the second-degree curve

     *            coefficient.

     * @param basePoint The point that generates the desired group

     * @param logCofactor The base-2 logarithm of the cofactor of the curve

     * @param oid

     * @param name

     */

    public XECParameters(int bits, BigInteger p, int a24,

                         byte basePoint, int logCofactor,

                         ObjectIdentifier oid, String name) {

        this.bits = bits;

        this.logCofactor = logCofactor;

        this.p = p;

        this.a24 = a24;

        this.basePoint = basePoint;

        this.oid = oid;

        this.name = name;

    }

    public int getBits() {

        return bits;

    }

    public int getBytes() {

        return (bits + 7) / 8;

    }

    public int getLogCofactor() {

        return logCofactor;

    }

    public BigInteger getP() {

        return p;

    }

    public int getA24() {

        return a24;

    }

    public byte getBasePoint() {

        return basePoint;

    }

    public ObjectIdentifier getOid() {

        return oid;

    }

    public String getName() {

        return name;

    }

    private static final Map<Integer, XECParameters> SIZE_MAP;

    private static final Map<ObjectIdentifier, XECParameters> OID_MAP;

    private static final Map<String, XECParameters> NAME_MAP;

    static {

        final BigInteger TWO = BigInteger.valueOf(2);

        Map<Integer, XECParameters> bySize = new HashMap<>();

        Map<ObjectIdentifier, XECParameters> byOid = new HashMap<>();

        Map<String, XECParameters> byName = new HashMap<>();

        // set up X25519

        try {

            BigInteger p = TWO.pow(255).subtract(BigInteger.valueOf(19));

            addParameters(255, p, 121665, (byte) 0x09, 3,

                new int[]{1, 3, 101, 110}, NamedParameterSpec.X25519.getName(),

                bySize, byOid, byName);

        } catch (IOException ex) {

            // Unable to set X25519 parameters---it will be disabled

        }

        // set up X448

        try {

            BigInteger p = TWO.pow(448).subtract(TWO.pow(224))

                .subtract(BigInteger.ONE);

            addParameters(448, p, 39081, (byte) 0x05, 2,

                new int[]{1, 3, 101, 111}, NamedParameterSpec.X448.getName(),

                bySize, byOid, byName);

        } catch (IOException ex) {

            // Unable to set X448 parameters---it will be disabled

        }

        SIZE_MAP = Collections.unmodifiableMap(bySize);

        OID_MAP = Collections.unmodifiableMap(byOid);

        NAME_MAP = Collections.unmodifiableMap(byName);

    }

    private static void addParameters(int bits, BigInteger p, int a24,

        byte basePoint, int logCofactor, int[] oidBytes, String name,

        Map<Integer, XECParameters> bySize,

        Map<ObjectIdentifier, XECParameters> byOid,

        Map<String, XECParameters> byName) throws IOException {

        ObjectIdentifier oid = new ObjectIdentifier(oidBytes);

        XECParameters params =

            new XECParameters(bits, p, a24, basePoint, logCofactor, oid, name);

        bySize.put(bits, params);

        byOid.put(oid, params);

        byName.put(name, params);

    }

    public static Optional<XECParameters> getByOid(ObjectIdentifier id) {

        return Optional.ofNullable(OID_MAP.get(id));

    }

    public static Optional<XECParameters> getBySize(int size) {

        return Optional.ofNullable(SIZE_MAP.get(size));

    }

    public static Optional<XECParameters> getByName(String name) {

        return Optional.ofNullable(NAME_MAP.get(name));

    }

    boolean oidEquals(XECParameters other) {

        return oid.equals(other.getOid());

    }

    // Utility method that is used by the methods below to handle exception

    // suppliers

    private static

    <A, B> Supplier<B> apply(final Function<A, B> func, final A a) {

        return new Supplier<B>() {

            @Override

            public B get() {

                return func.apply(a);

            }

        };

    }

    /**

     * Get parameters by key size, or throw an exception if no parameters are

     * defined for the specified key size. This method is used in several

     * contexts that should throw different exceptions when the parameters

     * are not found. The first argument is a function that produces the

     * desired exception.

     *

     * @param exception a function that produces an exception from a string

     * @param size the desired key size

     * @param <T> the type of exception that is thrown

     * @return the parameters for the specified key size

     * @throws T when suitable parameters do not exist

     */

    public static

    <T extends Throwable>

    XECParameters getBySize(Function<String, T> exception,

                            int size) throws T {

        Optional<XECParameters> xecParams = getBySize(size);

        return xecParams.orElseThrow(

            apply(exception, "Unsupported size: " + size));

    }

    /**

     * Get parameters by algorithm ID, or throw an exception if no

     * parameters are defined for the specified ID. This method is used in

     * several contexts that should throw different exceptions when the

     * parameters are not found. The first argument is a function that produces

     * the desired exception.

     *

     * @param exception a function that produces an exception from a string

     * @param algId the algorithm ID

     * @param <T> the type of exception that is thrown

     * @return the parameters for the specified algorithm ID

     * @throws T when suitable parameters do not exist

     */

    public static

    <T extends Throwable>

    XECParameters get(Function<String, T> exception,

                      AlgorithmId algId) throws T {

        Optional<XECParameters> xecParams = getByOid(algId.getOID());

        return xecParams.orElseThrow(

            apply(exception, "Unsupported OID: " + algId.getOID()));

    }

    /**

     * Get parameters by algorithm parameter spec, or throw an exception if no

     * parameters are defined for the spec. This method is used in

     * several contexts that should throw different exceptions when the

     * parameters are not found. The first argument is a function that produces

     * the desired exception.

     *

     * @param exception a function that produces an exception from a string

     * @param params the algorithm parameters spec

     * @param <T> the type of exception that is thrown

     * @return the parameters for the spec

     * @throws T when suitable parameters do not exist

     */

    public static

    <T extends Throwable>

    XECParameters get(Function<String, T> exception,

                      AlgorithmParameterSpec params) throws T {

        if (params instanceof NamedParameterSpec) {

            NamedParameterSpec namedParams = (NamedParameterSpec) params;

            Optional<XECParameters> xecParams =

                getByName(namedParams.getName());

            return xecParams.orElseThrow(

                apply(exception, "Unsupported name: " + namedParams.getName()));

        } else {

            throw exception.apply("Only NamedParameterSpec is supported.");

        }

    }

}