NativeSeedGenerator.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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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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(String seedFile) throws IOException {
        // seedFile is ignored.
        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);

    @Override
    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");
        }
    }

}