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

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 * 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.pkcs11;

import java.security.*;

import java.security.interfaces.ECPublicKey;

import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.*;

import static sun.security.pkcs11.TemplateManager.*;

import sun.security.pkcs11.wrapper.*;

import static sun.security.pkcs11.wrapper.PKCS11Constants.*;

/**

 * KeyAgreement implementation for ECDH.

 *

 * @author  Andreas Sterbenz

 * @since   1.6

 */

final class P11ECDHKeyAgreement extends KeyAgreementSpi {

    // token instance

    private final Token token;

    // algorithm name

    private final String algorithm;

    // mechanism id

    private final long mechanism;

    // private key, if initialized

    private P11Key privateKey;

    // encoded public point, non-null between doPhase() and generateSecret() only

    private byte[] publicValue;

    // length of the secret to be derived

    private int secretLen;

    P11ECDHKeyAgreement(Token token, String algorithm, long mechanism) {

        super();

        this.token = token;

        this.algorithm = algorithm;

        this.mechanism = mechanism;

    }

    // see JCE spec

    protected void engineInit(Key key, SecureRandom random)

            throws InvalidKeyException {

        if (key instanceof PrivateKey == false) {

            throw new InvalidKeyException

                        ("Key must be instance of PrivateKey");

        }

        privateKey = P11KeyFactory.convertKey(token, key, "EC");

        publicValue = null;

    }

    // see JCE spec

    protected void engineInit(Key key, AlgorithmParameterSpec params,

            SecureRandom random) throws InvalidKeyException,

            InvalidAlgorithmParameterException {

        if (params != null) {

            throw new InvalidAlgorithmParameterException

                        ("Parameters not supported");

        }

        engineInit(key, random);

    }

    // see JCE spec

    protected Key engineDoPhase(Key key, boolean lastPhase)

            throws InvalidKeyException, IllegalStateException {

        if (privateKey == null) {

            throw new IllegalStateException("Not initialized");

        }

        if (publicValue != null) {

            throw new IllegalStateException("Phase already executed");

        }

        if (lastPhase == false) {

            throw new IllegalStateException

                ("Only two party agreement supported, lastPhase must be true");

        }

        if (key instanceof ECPublicKey == false) {

            throw new InvalidKeyException

                ("Key must be a PublicKey with algorithm EC");

        }

        ECPublicKey ecKey = (ECPublicKey)key;

        int keyLenBits = ecKey.getParams().getCurve().getField().getFieldSize();

        secretLen = (keyLenBits + 7) >> 3;

        publicValue = P11ECKeyFactory.getEncodedPublicValue(ecKey);

        return null;

    }

    // see JCE spec

    protected byte[] engineGenerateSecret() throws IllegalStateException {

        if ((privateKey == null) || (publicValue == null)) {

            throw new IllegalStateException("Not initialized correctly");

        }

        Session session = null;

        try {

            session = token.getOpSession();

            CK_ATTRIBUTE[] attributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_CLASS, CKO_SECRET_KEY),

                new CK_ATTRIBUTE(CKA_KEY_TYPE, CKK_GENERIC_SECRET),

            };

            CK_ECDH1_DERIVE_PARAMS ckParams =

                    new CK_ECDH1_DERIVE_PARAMS(CKD_NULL, null, publicValue);

            attributes = token.getAttributes

                (O_GENERATE, CKO_SECRET_KEY, CKK_GENERIC_SECRET, attributes);

            long keyID = token.p11.C_DeriveKey(session.id(),

                new CK_MECHANISM(mechanism, ckParams), privateKey.keyID,

                attributes);

            attributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_VALUE)

            };

            token.p11.C_GetAttributeValue(session.id(), keyID, attributes);

            byte[] secret = attributes[0].getByteArray();

            token.p11.C_DestroyObject(session.id(), keyID);

            return secret;

        } catch (PKCS11Exception e) {

            throw new ProviderException("Could not derive key", e);

        } finally {

            publicValue = null;

            token.releaseSession(session);

        }

    }

    // see JCE spec

    protected int engineGenerateSecret(byte[] sharedSecret, int

            offset) throws IllegalStateException, ShortBufferException {

        if (offset + secretLen > sharedSecret.length) {

            throw new ShortBufferException("Need " + secretLen

                + " bytes, only " + (sharedSecret.length - offset) + " available");

        }

        byte[] secret = engineGenerateSecret();

        System.arraycopy(secret, 0, sharedSecret, offset, secret.length);

        return secret.length;

    }

    // see JCE spec

    protected SecretKey engineGenerateSecret(String algorithm)

            throws IllegalStateException, NoSuchAlgorithmException,

            InvalidKeyException {

        if (algorithm == null) {

            throw new NoSuchAlgorithmException("Algorithm must not be null");

        }

        if (algorithm.equals("TlsPremasterSecret") == false) {

            throw new NoSuchAlgorithmException

                ("Only supported for algorithm TlsPremasterSecret");

        }

        return nativeGenerateSecret(algorithm);

    }

    private SecretKey nativeGenerateSecret(String algorithm)

            throws IllegalStateException, NoSuchAlgorithmException,

            InvalidKeyException {

        if ((privateKey == null) || (publicValue == null)) {

            throw new IllegalStateException("Not initialized correctly");

        }

        long keyType = CKK_GENERIC_SECRET;

        Session session = null;

        try {

            session = token.getObjSession();

            CK_ATTRIBUTE[] attributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_CLASS, CKO_SECRET_KEY),

                new CK_ATTRIBUTE(CKA_KEY_TYPE, keyType),

            };

            CK_ECDH1_DERIVE_PARAMS ckParams =

                    new CK_ECDH1_DERIVE_PARAMS(CKD_NULL, null, publicValue);

            attributes = token.getAttributes

                (O_GENERATE, CKO_SECRET_KEY, keyType, attributes);

            long keyID = token.p11.C_DeriveKey(session.id(),

                new CK_MECHANISM(mechanism, ckParams), privateKey.keyID,

                attributes);

            CK_ATTRIBUTE[] lenAttributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_VALUE_LEN),

            };

            token.p11.C_GetAttributeValue(session.id(), keyID, lenAttributes);

            int keyLen = (int)lenAttributes[0].getLong();

            SecretKey key = P11Key.secretKey

                        (session, keyID, algorithm, keyLen << 3, attributes);

            return key;

        } catch (PKCS11Exception e) {

            throw new InvalidKeyException("Could not derive key", e);

        } finally {

            publicValue = null;

            token.releaseSession(session);

        }

    }

}