org.apache.hadoop.crypto.random.OpensslSecureRandom.java Source code

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Here is the source code for org.apache.hadoop.crypto.random.OpensslSecureRandom.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.crypto.random;

import java.util.Random;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.util.NativeCodeLoader;

import com.google.common.base.Preconditions;

/**
 * OpenSSL secure random using JNI.
 * This implementation is thread-safe.
 * <p/>
 * 
 * If using an Intel chipset with RDRAND, the high-performance hardware 
 * random number generator will be used and it's much faster than
 * {@link java.security.SecureRandom}. If RDRAND is unavailable, default
 * OpenSSL secure random generator will be used. It's still faster
 * and can generate strong random bytes.
 * <p/>
 * @see https://wiki.openssl.org/index.php/Random_Numbers
 * @see http://en.wikipedia.org/wiki/RdRand
 */
@InterfaceAudience.Private
public class OpensslSecureRandom extends Random {
    private static final long serialVersionUID = -7828193502768789584L;
    private static final Log LOG = LogFactory.getLog(OpensslSecureRandom.class.getName());

    /** If native SecureRandom unavailable, use java SecureRandom */
    private java.security.SecureRandom fallback = null;
    private static boolean nativeEnabled = false;
    static {
        if (NativeCodeLoader.isNativeCodeLoaded() && NativeCodeLoader.buildSupportsOpenssl()) {
            try {
                initSR();
                nativeEnabled = true;
            } catch (Throwable t) {
                LOG.error("Failed to load Openssl SecureRandom", t);
            }
        }
    }

    public static boolean isNativeCodeLoaded() {
        return nativeEnabled;
    }

    public OpensslSecureRandom() {
        if (!nativeEnabled) {
            fallback = new java.security.SecureRandom();
        }
    }

    /**
     * Generates a user-specified number of random bytes.
     * It's thread-safe.
     * 
     * @param bytes the array to be filled in with random bytes.
     */
    @Override
    public void nextBytes(byte[] bytes) {
        if (!nativeEnabled || !nextRandBytes(bytes)) {
            fallback.nextBytes(bytes);
        }
    }

    @Override
    public void setSeed(long seed) {
        // Self-seeding.
    }

    /**
     * Generates an integer containing the user-specified number of
     * random bits (right justified, with leading zeros).
     *
     * @param numBits number of random bits to be generated, where
     * 0 <= <code>numBits</code> <= 32.
     *
     * @return int an <code>int</code> containing the user-specified number
     * of random bits (right justified, with leading zeros).
     */
    @Override
    final protected int next(int numBits) {
        Preconditions.checkArgument(numBits >= 0 && numBits <= 32);
        int numBytes = (numBits + 7) / 8;
        byte b[] = new byte[numBytes];
        int next = 0;

        nextBytes(b);
        for (int i = 0; i < numBytes; i++) {
            next = (next << 8) + (b[i] & 0xFF);
        }

        return next >>> (numBytes * 8 - numBits);
    }

    private native static void initSR();

    private native boolean nextRandBytes(byte[] bytes);
}