MerkleHellmanKnapsackTest.java

MerkleHellmanKnapsackTest.java

package edu.cmu.cs771.hw1;

import java.nio.charset.Charset;
import java.util.*;
import java.math.BigInteger;

public class MerkleHellmanKnapsackTest {

        public MerkleHellmanKnapsackTest() {
                // TODO Auto-generated constructor stub
        }

        /**
         * @param args
         */
        public static void main(String[] args) {
                String plainTextStr = "a";
                LinkedList<Integer> wList = new LinkedList<Integer>();
                int wSum = 0;
                // w = {2, 7, 11, 21, 42, 89, 180, 354}
                int wInt[] = { 2, 7, 11, 21, 42, 89, 180, 354 };
                for (int i = 0; i < wInt.length; i++) {
                        wList.add(wInt[i]);
                }
                Iterator wIterator = wList.iterator();
                while (wIterator.hasNext()) {
                        wSum += Integer.parseInt(wIterator.next().toString());
                }
                System.out.println("The sum is : " + wSum);
                int qInt = 881;// qInt > wSum
                // generate the number that is in the range [1,q)
                for (int i = 1; i < qInt; i++) {
                        if (gcd(i, qInt) == 1 && i != 2) {
                                // System.out.println(i);
                        }
                }
                int rInt = 588;
                wIterator = wList.iterator();
                LinkedList<Integer> bList = new LinkedList<Integer>();
                while (wIterator.hasNext()) {
                        bList.add(Integer.parseInt(wIterator.next().toString()) * rInt
                                        % qInt);
                }
                System.out.println(bList.toString());
                //System.out.println(stringToBin(plainTextStr));
                Charset encoding = Charset.forName("US-ASCII");
                System.out.println(plainTextStr.getBytes(encoding));
                int ch = (int) plainTextStr.charAt(0);
                //System.out.println(Integer.toBinaryString(ch & 0xFF));
                String chBin = Integer.toBinaryString(ch & 0XFF);
                System.out.println(chBin);
                chBin = String.format("%8s", chBin).replace(' ', '0');
                System.out.println(chBin);
                
                Iterator bIterator = bList.iterator();
                int chBinIdx = 0;
                int chSum = 0;
                while(bIterator.hasNext()){
                        chSum += Integer.parseInt(bIterator.next().toString()) * Integer.parseInt(Character.toString(chBin.charAt(chBinIdx)));
                        chBinIdx ++;
                }
                System.out.println(chSum);
                BigInteger k = new BigInteger("588");
                BigInteger rMI = k.modInverse(new BigInteger("881"));
                //System.out.println(k.modInverse(new BigInteger("881")));
                int rr = (chSum * Integer.parseInt(rMI.toString())) % qInt;
                System.out.println(rr);
                wIterator = wList.descendingIterator();
                LinkedList<Integer> de = new LinkedList<Integer>();
                int tmp = 0;
                while(wIterator.hasNext()){
                        tmp = rr - Integer.parseInt(wIterator.next().toString());
                        if(tmp < 0){
                                de.addFirst(0);
                                //System.out.print(0);
                        }else{
                                rr = tmp;
                                de.addFirst(1);
                                //System.out.print(1);
                        }
                }
                System.out.println(de.toString());
                int test = 01100001;
                System.out.println((char) test);
                
        }

        public static int gcd(int a, int b) {
                if (b == 0)
                        return a;
                return gcd(b, a % b);
        }

        public static String[] stringToBin(String s) {
                System.out.println("Converting: " + s);
                byte[] b = s.getBytes();
                String[] sa = new String[s.getBytes().length];
                for (int i = 0; i < b.length; i++) {
                        sa[i] = Integer.toBinaryString(b[i] & 0xFF);
                }
                return sa;
        }

}