/*

 * Copyright 2002 Sun Microsystems, Inc.  All Rights Reserved.

 * 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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.security.provider;

import java.io.IOException;

/**

 * Seed generator for Windows making use of MS CryptoAPI using native code.

 *

 */

class NativeSeedGenerator extends SeedGenerator {

    /**

     * Create a new CryptoAPI seed generator instances.

     *

     * @exception IOException if CryptoAPI seeds are not available

     * on this platform.

     */

    NativeSeedGenerator() throws IOException {

        super();

        // try generating two random bytes to see if CAPI is available

        if (!nativeGenerateSeed(new byte[2])) {

            throw new IOException("Required native CryptoAPI features not "

                                  + " available on this machine");

        }

    }

    /**

     * Native method to do the actual work.

     */

    private static native boolean nativeGenerateSeed(byte[] result);

    void getSeedBytes(byte[] result) {

        // fill array as a side effect

        if (nativeGenerateSeed(result) == false) {

            // should never happen if constructor check succeeds

            throw new InternalError

                            ("Unexpected CryptoAPI failure generating seed");

        }

    }

    byte getSeedByte() {

        byte[] b = new byte[1];

        getSeedBytes(b);

        return b[0];

    }

}