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 * 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

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package sun.security.ec;

import java.security.*;

import java.security.interfaces.*;

import java.security.spec.*;

/**

 * KeyFactory for EC keys. Keys must be instances of PublicKey or PrivateKey

 * and getAlgorithm() must return "EC". For such keys, it supports conversion

 * between the following:

 *

 * For public keys:

 *  . PublicKey with an X.509 encoding

 *  . ECPublicKey

 *  . ECPublicKeySpec

 *  . X509EncodedKeySpec

 *

 * For private keys:

 *  . PrivateKey with a PKCS#8 encoding

 *  . ECPrivateKey

 *  . ECPrivateKeySpec

 *  . PKCS8EncodedKeySpec

 *

 * @since   1.6

 * @author  Andreas Sterbenz

 */

public final class ECKeyFactory extends KeyFactorySpi {

    // Used by translateKey()

    private static KeyFactory instance;

    private static KeyFactory getInstance() {

        if (instance == null) {

            try {

                instance = KeyFactory.getInstance("EC", "SunEC");

            } catch (NoSuchProviderException e) {

                throw new RuntimeException(e);

            } catch (NoSuchAlgorithmException e) {

                throw new RuntimeException(e);

            }

        }

        return instance;

    }

    public ECKeyFactory() {

        // empty

    }

    /**

     * Static method to convert Key into a useable instance of

     * ECPublicKey or ECPrivateKey. Check the key and convert it

     * to a Sun key if necessary. If the key is not an EC key

     * or cannot be used, throw an InvalidKeyException.

     *

     * The difference between this method and engineTranslateKey() is that

     * we do not convert keys of other providers that are already an

     * instance of ECPublicKey or ECPrivateKey.

     *

     * To be used by future Java ECDSA and ECDH implementations.

     */

    public static ECKey toECKey(Key key) throws InvalidKeyException {

        if (key instanceof ECKey) {

            ECKey ecKey = (ECKey)key;

            checkKey(ecKey);

            return ecKey;

        } else {

            /*

             * We don't call the engineTranslateKey method directly

             * because KeyFactory.translateKey adds code to loop through

             * all key factories.

             */

            return (ECKey)getInstance().translateKey(key);

        }

    }

    /**

     * Check that the given EC key is valid.

     */

    private static void checkKey(ECKey key) throws InvalidKeyException {

        // check for subinterfaces, omit additional checks for our keys

        if (key instanceof ECPublicKey) {

            if (key instanceof ECPublicKeyImpl) {

                return;

            }

        } else if (key instanceof ECPrivateKey) {

            if (key instanceof ECPrivateKeyImpl) {

                return;

            }

        } else {

            throw new InvalidKeyException("Neither a public nor a private key");

        }

        // ECKey does not extend Key, so we need to do a cast

        String keyAlg = ((Key)key).getAlgorithm();

        if (keyAlg.equals("EC") == false) {

            throw new InvalidKeyException("Not an EC key: " + keyAlg);

        }

        // XXX further sanity checks about whether this key uses supported

        // fields, point formats, etc. would go here

    }

    /**

     * Translate an EC key into a Sun EC key. If conversion is

     * not possible, throw an InvalidKeyException.

     * See also JCA doc.

     */

    protected Key engineTranslateKey(Key key) throws InvalidKeyException {

        if (key == null) {

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

        }

        String keyAlg = key.getAlgorithm();

        if (keyAlg.equals("EC") == false) {

            throw new InvalidKeyException("Not an EC key: " + keyAlg);

        }

        if (key instanceof PublicKey) {

            return implTranslatePublicKey((PublicKey)key);

        } else if (key instanceof PrivateKey) {

            return implTranslatePrivateKey((PrivateKey)key);

        } else {

            throw new InvalidKeyException("Neither a public nor a private key");

        }

    }

    // see JCA doc

    protected PublicKey engineGeneratePublic(KeySpec keySpec)

            throws InvalidKeySpecException {

        try {

            return implGeneratePublic(keySpec);

        } catch (InvalidKeySpecException e) {

            throw e;

        } catch (GeneralSecurityException e) {

            throw new InvalidKeySpecException(e);

        }

    }

    // see JCA doc

    protected PrivateKey engineGeneratePrivate(KeySpec keySpec)

            throws InvalidKeySpecException {

        try {

            return implGeneratePrivate(keySpec);

        } catch (InvalidKeySpecException e) {

            throw e;

        } catch (GeneralSecurityException e) {

            throw new InvalidKeySpecException(e);

        }

    }

    // internal implementation of translateKey() for public keys. See JCA doc

    private PublicKey implTranslatePublicKey(PublicKey key)

            throws InvalidKeyException {

        if (key instanceof ECPublicKey) {

            if (key instanceof ECPublicKeyImpl) {

                return key;

            }

            ECPublicKey ecKey = (ECPublicKey)key;

            return new ECPublicKeyImpl(

                ecKey.getW(),

                ecKey.getParams()

            );

        } else if ("X.509".equals(key.getFormat())) {

            byte[] encoded = key.getEncoded();

            return new ECPublicKeyImpl(encoded);

        } else {

            throw new InvalidKeyException("Public keys must be instance "

                + "of ECPublicKey or have X.509 encoding");

        }

    }

    // internal implementation of translateKey() for private keys. See JCA doc

    private PrivateKey implTranslatePrivateKey(PrivateKey key)

            throws InvalidKeyException {

        if (key instanceof ECPrivateKey) {

            if (key instanceof ECPrivateKeyImpl) {

                return key;

            }

            ECPrivateKey ecKey = (ECPrivateKey)key;

            return new ECPrivateKeyImpl(

                ecKey.getS(),

                ecKey.getParams()

            );

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

            return new ECPrivateKeyImpl(key.getEncoded());

        } else {

            throw new InvalidKeyException("Private keys must be instance "

                + "of ECPrivateKey or have PKCS#8 encoding");

        }

    }

    // internal implementation of generatePublic. See JCA doc

    private PublicKey implGeneratePublic(KeySpec keySpec)

            throws GeneralSecurityException {

        if (keySpec instanceof X509EncodedKeySpec) {

            X509EncodedKeySpec x509Spec = (X509EncodedKeySpec)keySpec;

            return new ECPublicKeyImpl(x509Spec.getEncoded());

        } else if (keySpec instanceof ECPublicKeySpec) {

            ECPublicKeySpec ecSpec = (ECPublicKeySpec)keySpec;

            return new ECPublicKeyImpl(

                ecSpec.getW(),

                ecSpec.getParams()

            );

        } else {

            throw new InvalidKeySpecException("Only ECPublicKeySpec "

                + "and X509EncodedKeySpec supported for EC public keys");

        }

    }

    // internal implementation of generatePrivate. See JCA doc

    private PrivateKey implGeneratePrivate(KeySpec keySpec)

            throws GeneralSecurityException {

        if (keySpec instanceof PKCS8EncodedKeySpec) {

            PKCS8EncodedKeySpec pkcsSpec = (PKCS8EncodedKeySpec)keySpec;

            return new ECPrivateKeyImpl(pkcsSpec.getEncoded());

        } else if (keySpec instanceof ECPrivateKeySpec) {

            ECPrivateKeySpec ecSpec = (ECPrivateKeySpec)keySpec;

            return new ECPrivateKeyImpl(ecSpec.getS(), ecSpec.getParams());

        } else {

            throw new InvalidKeySpecException("Only ECPrivateKeySpec "

                + "and PKCS8EncodedKeySpec supported for EC private keys");

        }

    }

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

            throws InvalidKeySpecException {

        try {

            // convert key to one of our keys

            // this also verifies that the key is a valid EC key and ensures

            // that the encoding is X.509/PKCS#8 for public/private keys

            key = engineTranslateKey(key);

        } catch (InvalidKeyException e) {

            throw new InvalidKeySpecException(e);

        }

        if (key instanceof ECPublicKey) {

            ECPublicKey ecKey = (ECPublicKey)key;

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

                return keySpec.cast(new ECPublicKeySpec(

                    ecKey.getW(),

                    ecKey.getParams()

                ));

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

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

            } else {

                throw new InvalidKeySpecException

                        ("KeySpec must be ECPublicKeySpec or "

                        + "X509EncodedKeySpec for EC public keys");

            }

        } else if (key instanceof ECPrivateKey) {

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

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

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

                ECPrivateKey ecKey = (ECPrivateKey)key;

                return keySpec.cast(new ECPrivateKeySpec(

                    ecKey.getS(),

                    ecKey.getParams()

                ));

            } else {

                throw new InvalidKeySpecException

                        ("KeySpec must be ECPrivateKeySpec or "

                        + "PKCS8EncodedKeySpec for EC private keys");

            }

        } else {

            // should not occur, caught in engineTranslateKey()

            throw new InvalidKeySpecException("Neither public nor private key");

        }

    }

}