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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
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package sun.security.ec.ed;

import sun.security.pkcs.PKCS8Key;

import java.security.*;
import java.security.interfaces.*;
import java.security.spec.*;
import java.util.Arrays;
import java.util.function.Function;

public class EdDSAKeyFactory extends KeyFactorySpi {

    private EdDSAParameters lockedParams = null;

    public EdDSAKeyFactory() {
        // do nothing
    }

    protected EdDSAKeyFactory(NamedParameterSpec paramSpec) {
        lockedParams = EdDSAParameters.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 EdECKey) {
            EdECKey edKey = (EdECKey) key;
            EdDSAParameters params = EdDSAParameters.get(
                InvalidKeyException::new, edKey.getParams());
            checkLockedParams(InvalidKeyException::new, params);

            if (edKey instanceof EdECPublicKey) {
                EdECPublicKey publicKey = (EdECPublicKey) edKey;
                return new EdDSAPublicKeyImpl(params, publicKey.getPoint());
            } else if (edKey instanceof EdECPrivateKey) {
                EdECPrivateKey privateKey = (EdECPrivateKey) edKey;
                byte[] privateKeyBytes = privateKey.getBytes().orElseThrow(
                    () -> new InvalidKeyException("No private key data"));
                return new EdDSAPrivateKeyImpl(params, privateKeyBytes);
            } else {
                throw new InvalidKeyException("Unsupported EdECKey subclass");
            }
        } else if (key instanceof PublicKey &&
                   key.getFormat().equals("X.509")) {
            EdDSAPublicKeyImpl result =
                new EdDSAPublicKeyImpl(key.getEncoded());
            checkLockedParams(InvalidKeyException::new, result.getParams());
            return result;
        } else if (key instanceof PrivateKey &&
                   key.getFormat().equals("PKCS#8")) {
            byte[] encoded = key.getEncoded();
            try {
                EdDSAPrivateKeyImpl result =
                        new EdDSAPrivateKeyImpl(encoded);
                checkLockedParams(InvalidKeyException::new, result.getParams());
                return result;
            } finally {
                Arrays.fill(encoded, (byte)0);
            }
        } else {
            throw new InvalidKeyException("Unsupported key type or format");
        }
    }

    private
    <T extends Throwable>
    void checkLockedParams(Function<String, T> exception,
                           NamedParameterSpec spec) throws T {

        EdDSAParameters params = EdDSAParameters.get(exception, spec);
        checkLockedParams(exception, params);
    }

    private
    <T extends Throwable>
    void checkLockedParams(Function<String, T> exception,
                           EdDSAParameters 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 {

        return switch (keySpec) {
            case X509EncodedKeySpec x509Spec -> {
                EdDSAPublicKeyImpl result =
                    new EdDSAPublicKeyImpl(x509Spec.getEncoded());
                checkLockedParams(InvalidKeySpecException::new,
                    result.getParams());
                yield result;
            }
            case EdECPublicKeySpec publicKeySpec -> {
                EdDSAParameters params = EdDSAParameters.get(
                    InvalidKeySpecException::new, publicKeySpec.getParams());
                checkLockedParams(InvalidKeySpecException::new, params);
                yield new EdDSAPublicKeyImpl(params, publicKeySpec.getPoint());
            }
            case PKCS8EncodedKeySpec p8 -> {
                PKCS8Key p8key = new EdDSAPrivateKeyImpl(p8.getEncoded());
                if (!p8key.hasPublicKey()) {
                    throw new InvalidKeySpecException("No public key found.");
                }
                yield new EdDSAPublicKeyImpl(p8key.getPubKeyEncoded());
            }
            case null -> throw new InvalidKeySpecException(
                "keySpec must not be null");
            default ->
                throw new InvalidKeySpecException(keySpec.getClass().getName() +
                    " not supported.");
        };
    }

    private PrivateKey generatePrivateImpl(KeySpec keySpec)
        throws InvalidKeyException, InvalidKeySpecException {

        return switch (keySpec) {
            case PKCS8EncodedKeySpec pkcsSpec -> {
                byte[] encoded = pkcsSpec.getEncoded();
                try {
                    EdDSAPrivateKeyImpl result =
                        new EdDSAPrivateKeyImpl(encoded);
                    checkLockedParams(InvalidKeySpecException::new,
                        result.getParams());
                    yield result;
                } finally {
                    Arrays.fill(encoded, (byte) 0);
                }
            }
            case EdECPrivateKeySpec privateKeySpec -> {
                EdDSAParameters params = EdDSAParameters.get(
                    InvalidKeySpecException::new, privateKeySpec.getParams());
                checkLockedParams(InvalidKeySpecException::new, params);
                byte[] bytes = privateKeySpec.getBytes();
                try {
                    yield new EdDSAPrivateKeyImpl(params, bytes);
                } finally {
                    Arrays.fill(bytes, (byte) 0);
                }
            }
            case null -> throw new InvalidKeySpecException(
                "keySpec must not be null");
            default ->
                throw new InvalidKeySpecException(keySpec.getClass().getName() +
                    " not supported.");
        };
    }

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

        if (key instanceof EdECPublicKey) {
            checkLockedParams(InvalidKeySpecException::new,
                ((EdECPublicKey) key).getParams());

            if (keySpec.isAssignableFrom(X509EncodedKeySpec.class)) {
                if (!key.getFormat().equals("X.509")) {
                    throw new InvalidKeySpecException("Format is not X.509");
                }
                return keySpec.cast(new X509EncodedKeySpec(key.getEncoded()));
            } else if (keySpec.isAssignableFrom(EdECPublicKeySpec.class)) {
                EdECPublicKey edKey = (EdECPublicKey) key;
                return keySpec.cast(
                    new EdECPublicKeySpec(edKey.getParams(), edKey.getPoint()));
            } else {
                throw new InvalidKeySpecException(
                    "KeySpec must be X509EncodedKeySpec or EdECPublicKeySpec");
            }
        } else if (key instanceof EdECPrivateKey) {
            checkLockedParams(InvalidKeySpecException::new,
                ((EdECPrivateKey) key).getParams());

            if (keySpec.isAssignableFrom(PKCS8EncodedKeySpec.class)) {
                if (!key.getFormat().equals("PKCS#8")) {
                    throw new InvalidKeySpecException("Format is not PKCS#8");
                }
                byte[] encoded = key.getEncoded();
                try {
                    return keySpec.cast(new PKCS8EncodedKeySpec(encoded));
                } finally {
                    Arrays.fill(encoded, (byte)0);
                }
            } else if (keySpec.isAssignableFrom(EdECPrivateKeySpec.class)) {
                EdECPrivateKey edKey = (EdECPrivateKey) key;
                byte[] scalar = edKey.getBytes().orElseThrow(
                    () -> new InvalidKeySpecException("No private key value")
                );
                try {
                    return keySpec.cast(
                            new EdECPrivateKeySpec(edKey.getParams(), scalar));
                } finally {
                    Arrays.fill(scalar, (byte)0);
                }
            } else {
                throw new InvalidKeySpecException
                ("KeySpec must be PKCS8EncodedKeySpec or EdECPrivateKeySpec");
            }
        } else {
            throw new InvalidKeySpecException("Unsupported key type");
        }
    }

    public static class Ed25519 extends EdDSAKeyFactory {

        public Ed25519() {
            super(NamedParameterSpec.ED25519);
        }
    }

    public static class Ed448 extends EdDSAKeyFactory {

        public Ed448() {
            super(NamedParameterSpec.ED448);
        }
    }
}