org.apache.pirk.responder.wideskies.spark.ExpTableGenerator.java Source code

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Here is the source code for org.apache.pirk.responder.wideskies.spark.ExpTableGenerator.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.pirk.responder.wideskies.spark;

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;

import org.apache.pirk.encryption.ModPowAbstraction;
import org.apache.pirk.query.wideskies.Query;
import org.apache.spark.api.java.function.PairFlatMapFunction;

import scala.Tuple2;

/**
 * Class to generate the query element modular exponentiations
 * <p>
 *
 */
public class ExpTableGenerator implements PairFlatMapFunction<Integer, Integer, Tuple2<Integer, BigInteger>> {
    private static final long serialVersionUID = 1L;

    Query query = null;
    private BigInteger NSquared = null;
    private int maxValue = 0;

    public ExpTableGenerator(BroadcastVars bbVarsIn) {
        query = bbVarsIn.getQuery();
        NSquared = query.getNSquared();

        int dataPartitionBitSize = query.getQueryInfo().getDataPartitionBitSize();
        maxValue = (int) Math.pow(2, dataPartitionBitSize) - 1;
    }

    @Override
    public Iterable<Tuple2<Integer, Tuple2<Integer, BigInteger>>> call(Integer queryHashKey) throws Exception {
        // queryHashKey -> <<power>,<element^power mod N^2>>
        List<Tuple2<Integer, Tuple2<Integer, BigInteger>>> modExp = new ArrayList<>();

        BigInteger element = query.getQueryElement(queryHashKey);
        for (int i = 0; i <= maxValue; ++i) {
            BigInteger modPow = ModPowAbstraction.modPow(element, BigInteger.valueOf(i), NSquared);
            Tuple2<Integer, BigInteger> modPowTuple = new Tuple2<>(i, modPow);
            modExp.add(new Tuple2<>(queryHashKey, modPowTuple));
        }

        return modExp;
    }
}