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

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 * 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.

 *

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package sun.security.ec;

import java.security.KeyFactorySpi;

import java.security.Key;

import java.security.PublicKey;

import java.security.PrivateKey;

import java.security.InvalidKeyException;

import java.security.ProviderException;

import java.security.interfaces.XECKey;

import java.security.interfaces.XECPrivateKey;

import java.security.interfaces.XECPublicKey;

import java.security.spec.AlgorithmParameterSpec;

import java.security.spec.NamedParameterSpec;

import java.security.spec.KeySpec;

import java.security.spec.InvalidKeySpecException;

import java.security.spec.PKCS8EncodedKeySpec;

import java.security.spec.X509EncodedKeySpec;

import java.security.spec.XECPublicKeySpec;

import java.security.spec.XECPrivateKeySpec;

import java.util.function.Function;

public class XDHKeyFactory extends KeyFactorySpi {

    private XECParameters lockedParams = null;

    XDHKeyFactory() {

        // do nothing

    }

    protected XDHKeyFactory(AlgorithmParameterSpec paramSpec) {

        lockedParams = XECParameters.get(ProviderException::new, paramSpec);

    }

    @Override

    protected Key engineTranslateKey(Key key) throws InvalidKeyException {

        if (key == null) {

            throw new InvalidKeyException("Key must not be null");

        }

        if (key instanceof XECKey) {

            XECKey xecKey = (XECKey) key;

            XECParameters params = XECParameters.get(InvalidKeyException::new,

                xecKey.getParams());

            checkLockedParams(InvalidKeyException::new, params);

            if (xecKey instanceof XECPublicKey) {

                XECPublicKey publicKey = (XECPublicKey) xecKey;

                return new XDHPublicKeyImpl(params, publicKey.getU());

            } else if (xecKey instanceof XECPrivateKey) {

                XECPrivateKey privateKey = (XECPrivateKey) xecKey;

                byte[] scalar = privateKey.getScalar().orElseThrow(

                    () -> new InvalidKeyException("No private key data"));

                return new XDHPrivateKeyImpl(params, scalar);

            } else {

                throw new InvalidKeyException("Unsupported XECKey subclass");

            }

        } else if (key instanceof PublicKey &&

                   key.getFormat().equals("X.509")) {

            XDHPublicKeyImpl result = new XDHPublicKeyImpl(key.getEncoded());

            checkLockedParams(InvalidKeyException::new, result.getParams());

            return result;

        } else if (key instanceof PrivateKey &&

                   key.getFormat().equals("PKCS#8")) {

            XDHPrivateKeyImpl result =  new XDHPrivateKeyImpl(key.getEncoded());

            checkLockedParams(InvalidKeyException::new, result.getParams());

            return result;

        } else {

            throw new InvalidKeyException("Unsupported key type or format");

        }

    }

    private

    <T extends Throwable>

    void checkLockedParams(Function<String, T> exception,

                           AlgorithmParameterSpec spec) throws T {

        XECParameters params = XECParameters.get(exception, spec);

        checkLockedParams(exception, params);

    }

    private

    <T extends Throwable>

    void checkLockedParams(Function<String, T> exception,

                           XECParameters params) throws T {

        if (lockedParams != null && lockedParams != params) {

            throw exception.apply("Parameters must be " +

                lockedParams.getName());

        }

    }

    @Override

    protected PublicKey engineGeneratePublic(KeySpec keySpec)

        throws InvalidKeySpecException {

        try {

             return generatePublicImpl(keySpec);

        } catch (InvalidKeyException ex) {

            throw new InvalidKeySpecException(ex);

        }

    }

    @Override

    protected PrivateKey engineGeneratePrivate(KeySpec keySpec)

        throws InvalidKeySpecException {

        try {

            return generatePrivateImpl(keySpec);

        } catch (InvalidKeyException ex) {

            throw new InvalidKeySpecException(ex);

        }

    }

    private PublicKey generatePublicImpl(KeySpec keySpec)

        throws InvalidKeyException, InvalidKeySpecException {

        if (keySpec instanceof X509EncodedKeySpec) {

            X509EncodedKeySpec x509Spec = (X509EncodedKeySpec) keySpec;

            XDHPublicKeyImpl result =

                new XDHPublicKeyImpl(x509Spec.getEncoded());

            checkLockedParams(InvalidKeySpecException::new,

                result.getParams());

            return result;

        } else if (keySpec instanceof XECPublicKeySpec) {

            XECPublicKeySpec publicKeySpec = (XECPublicKeySpec) keySpec;

            XECParameters params = XECParameters.get(

                InvalidKeySpecException::new, publicKeySpec.getParams());

            checkLockedParams(InvalidKeySpecException::new, params);

            return new XDHPublicKeyImpl(params, publicKeySpec.getU());

        } else {

            throw new InvalidKeySpecException(

                "Only X509EncodedKeySpec and XECPublicKeySpec are supported");

        }

    }

    private PrivateKey generatePrivateImpl(KeySpec keySpec)

        throws InvalidKeyException, InvalidKeySpecException {

        if (keySpec instanceof PKCS8EncodedKeySpec) {

            PKCS8EncodedKeySpec pkcsSpec = (PKCS8EncodedKeySpec) keySpec;

            XDHPrivateKeyImpl result =

                new XDHPrivateKeyImpl(pkcsSpec.getEncoded());

            checkLockedParams(InvalidKeySpecException::new,

                result.getParams());

            return result;

        } else if (keySpec instanceof XECPrivateKeySpec) {

            XECPrivateKeySpec privateKeySpec = (XECPrivateKeySpec) keySpec;

            XECParameters params = XECParameters.get(

                InvalidKeySpecException::new, privateKeySpec.getParams());

            checkLockedParams(InvalidKeySpecException::new, params);

            return new XDHPrivateKeyImpl(params, privateKeySpec.getScalar());

        } else {

            throw new InvalidKeySpecException(

                "Only PKCS8EncodedKeySpec and XECPrivateKeySpec supported");

        }

    }

    protected <T extends KeySpec> T engineGetKeySpec(Key key, Class<T> keySpec)

            throws InvalidKeySpecException {

        if (key instanceof XECPublicKey) {

            checkLockedParams(InvalidKeySpecException::new,

                ((XECPublicKey) key).getParams());

            if (X509EncodedKeySpec.class.isAssignableFrom(keySpec)) {

                if (!key.getFormat().equals("X.509")) {

                    throw new InvalidKeySpecException("Format is not X.509");

                }

                return keySpec.cast(new X509EncodedKeySpec(key.getEncoded()));

            } else if (XECPublicKeySpec.class.isAssignableFrom(keySpec)) {

                XECPublicKey xecKey = (XECPublicKey) key;

                return keySpec.cast(

                    new XECPublicKeySpec(xecKey.getParams(), xecKey.getU()));

            } else {

                throw new InvalidKeySpecException(

                    "KeySpec must be X509EncodedKeySpec or XECPublicKeySpec");

            }

        } else if (key instanceof XECPrivateKey) {

            checkLockedParams(InvalidKeySpecException::new,

                ((XECPrivateKey) key).getParams());

            if (PKCS8EncodedKeySpec.class.isAssignableFrom(keySpec)) {

                if (!key.getFormat().equals("PKCS#8")) {

                    throw new InvalidKeySpecException("Format is not PKCS#8");

                }

                return keySpec.cast(new PKCS8EncodedKeySpec(key.getEncoded()));

            } else if (XECPrivateKeySpec.class.isAssignableFrom(keySpec)) {

                XECPrivateKey xecKey = (XECPrivateKey) key;

                byte[] scalar = xecKey.getScalar().orElseThrow(

                    () -> new InvalidKeySpecException("No private key value")

                );

                return keySpec.cast(

                    new XECPrivateKeySpec(xecKey.getParams(), scalar));

            } else {

                throw new InvalidKeySpecException

                ("KeySpec must be PKCS8EncodedKeySpec or XECPrivateKeySpec");

            }

        } else {

            throw new InvalidKeySpecException("Unsupported key type");

        }

    }

    static class X25519 extends XDHKeyFactory {

        public X25519() {

            super(NamedParameterSpec.X25519);

        }

    }

    static class X448 extends XDHKeyFactory {

        public X448() {

            super(NamedParameterSpec.X448);

        }

    }

}