/*

 * 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.ssl;

import java.security.*;

/**

 * The "KeyManager" for ephemeral RSA keys. Ephemeral DH and ECDH keys

 * are handled by the DHCrypt and ECDHCrypt classes, respectively.

 *

 * @author  Andreas Sterbenz

 */

final class EphemeralKeyManager {

    // indices for the keys array below

    private static final int INDEX_RSA512 = 0;

    private static final int INDEX_RSA1024 = 1;

    /*

     * Current cached RSA KeyPairs. Elements are never null.

     * Indexed via the constants above.

     */

    private final EphemeralKeyPair[] keys = new EphemeralKeyPair[] {

        new EphemeralKeyPair(null),

        new EphemeralKeyPair(null),

    };

    EphemeralKeyManager() {

        // empty

    }

    /*

     * Get a temporary RSA KeyPair.

     */

    KeyPair getRSAKeyPair(boolean export, SecureRandom random) {

        int length, index;

        if (export) {

            length = 512;

            index = INDEX_RSA512;

        } else {

            length = 1024;

            index = INDEX_RSA1024;

        }

        synchronized (keys) {

            KeyPair kp = keys[index].getKeyPair();

            if (kp == null) {

                try {

                    KeyPairGenerator kgen = JsseJce.getKeyPairGenerator("RSA");

                    kgen.initialize(length, random);

                    keys[index] = new EphemeralKeyPair(kgen.genKeyPair());

                    kp = keys[index].getKeyPair();

                } catch (Exception e) {

                    // ignore

                }

            }

            return kp;

        }

    }

    /**

     * Inner class to handle storage of ephemeral KeyPairs.

     */

    private static class EphemeralKeyPair {

        // maximum number of times a KeyPair is used

        private static final int MAX_USE = 200;

        // maximum time interval in which the keypair is used (1 hour in ms)

        private static final long USE_INTERVAL = 3600*1000;

        private KeyPair keyPair;

        private int uses;

        private long expirationTime;

        private EphemeralKeyPair(KeyPair keyPair) {

            this.keyPair = keyPair;

            expirationTime = System.currentTimeMillis() + USE_INTERVAL;

        }

        /*

         * Check if the KeyPair can still be used.

         */

        private boolean isValid() {

            return (keyPair != null) && (uses < MAX_USE)

                   && (System.currentTimeMillis() < expirationTime);

        }

        /*

         * Return the KeyPair or null if it is invalid.

         */

        private KeyPair getKeyPair() {

            if (isValid() == false) {

                keyPair = null;

                return null;

            }

            uses++;

            return keyPair;

        }

    }

}