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‎DES, RSA, Rabin cryptosystem/desprog1.java

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import java.lang.*;
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import java.io.*;
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import java.util.Scanner;
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import java.math.BigInteger;
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class DesCrypto{
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public String desEncryption(String cipher, String Key){
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int[] IP={
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58,50,42,34,26,18,10,2,
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60,52,44,36,28,20,12,4,
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62,54,46,38,30,22,14,6,
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64,56,48,40,32,24,16,8,
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57,49,41,33,25,17,9,1,
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59,51,43,35,27,19,11,3,
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61,53,45,37,29,21,13,5,
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63,55,47,39,31,23,15,7};
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String BinCipher = HextoBinSplit(cipher);
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String L = BinCipher.substring(0,32);
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String R = BinCipher.substring(32);
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String BinKey = HextoBinSplit(Key);
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String IPvals = new String();
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for (int i=0;i<64;i++){
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IPvals = IPvals+BinCipher.charAt(IP[i]-1);
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}
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String sixteenkeys[]=SixteenSubkeys(BinKey);
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String plainvals = processDES(IPvals,sixteenkeys);
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String finalHexa = new String();
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String[] substrings = plainvals.split("(?<=\\G.{8})");
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for(int i=0;i<substrings.length;i++){
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int dec = Integer.parseInt(substrings[i],2);
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String dummy = Integer.toString(dec,16);
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int len = dummy.length();
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if(len < 2)
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{
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for (int k=0;k<2-len;k++){
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dummy = "0"+dummy;
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}
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}
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finalHexa = finalHexa + dummy;
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}
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return finalHexa;
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}
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public String desDecryption(String cipher, String Key){
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int[] IP={
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58,50,42,34,26,18,10,2,
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60,52,44,36,28,20,12,4,
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62,54,46,38,30,22,14,6,
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64,56,48,40,32,24,16,8,
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57,49,41,33,25,17,9,1,
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59,51,43,35,27,19,11,3,
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61,53,45,37,29,21,13,5,
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63,55,47,39,31,23,15,7};
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String BinCipher = HextoBinSplit(cipher);
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String L = BinCipher.substring(0,32);
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String R = BinCipher.substring(32);
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String BinKey = HextoBinSplit(Key);
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String IPvals = new String();
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for (int i=0;i<64;i++){
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IPvals = IPvals+BinCipher.charAt(IP[i]-1);
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}
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String sixteenkeys[]=SixteenSubkeys(BinKey);
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String[] InverseKeys = new String[16];
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for(int i=15,j=0;i>=0;i--,j++){
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InverseKeys[j] = sixteenkeys[i];
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}
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//String plainvals = processDES(IPvals,sixteenkeys);
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String plainvals = processDES(IPvals,InverseKeys);
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//binary to Hexadecimal
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String finalHexa = new String();
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String[] substrings = plainvals.split("(?<=\\G.{8})");
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for(int i=0;i<substrings.length;i++){
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int dec = Integer.parseInt(substrings[i],2);
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String dummy = Integer.toString(dec,16);
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int len = dummy.length();
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if(len < 2)
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{
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for (int k=0;k<2-len;k++){
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dummy = "0"+dummy;
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}
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}
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finalHexa = finalHexa + dummy;
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}
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return finalHexa;
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}
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public String Sbox(String KE){
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int[][][] S={
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{{14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7},
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{0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8},
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{4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0},
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{15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13}
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},
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{
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{15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10},
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{3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5},
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{0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15},
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{13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9}
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},
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{
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{10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8},
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{13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1},
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{13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7},
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{1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12}
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},
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{
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{7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15},
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{13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9},
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{10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4},
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{3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14}
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},
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{
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{2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9},
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{14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6},
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{4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14},
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{11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3},
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},
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{
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{12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11},
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{10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8},
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{9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6},
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{4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13}
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},
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{
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{4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1},
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{13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6},
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{1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2},
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{6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12}
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},
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{
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{13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7},
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{1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2},
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{7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8},
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{2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11}
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}
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};
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int[] P={
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16,7,20,21,
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29,12,28,17,
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1,15,23,26,
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5,18,31,10,
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2,8,24,14,
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32,27,3,9,
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19,13,30,6,
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22,11,4,25
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};
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String[] substrings_8 = KE.split("(?<=\\G.{6})");
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String S_8 = new String();
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for(int l=0;l<8;l++){
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String temp = substrings_8[l];
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int i = Integer.parseInt(temp.substring(0,1)+temp.substring(5,6),2);
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int j = Integer.parseInt(temp.substring(1,5),2);
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int val = S[l][i][j];
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String res = Integer.toString(val,2);
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int len = res.length();
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if(len < 4)
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{
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for (int k=0;k<4-len;k++){
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res = "0"+res;
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}
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}
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S_8 = S_8 + res;
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}
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String finalRes = new String();
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for(int i=0;i<32;i++){
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finalRes = finalRes +S_8.charAt(P[i]-1);
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}
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return finalRes;
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}
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public String xorFun(String L, String R, String Key){
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int[] E={
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32,1,2,3,4,5,
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4,5,6,7,8,9,
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8,9,10,11,12,13,
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12,13,14,15,16,17,
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16,17,18,19,20,21,
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20,21,22,23,24,25,
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24,25,26,27,28,29,
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28,29,30,31,32,1};
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//change 32 to 48 bit; E(R)
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String R_48 = new String();
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for(int i=0;i<48;i++){
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R_48 = R_48 +R.charAt(E[i]-1);
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}
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//xor
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String KE = new String();
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for(int i=0;i<48;i++){
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KE = KE + Integer.toString(Character.getNumericValue(R_48.charAt(i))^Character.getNumericValue(Key.charAt(i)));
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}
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//Sbox
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String res = Sbox(KE);
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String resAfterXor = new String();
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for(int i=0;i<32;i++){
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resAfterXor = resAfterXor + Integer.toString(Character.getNumericValue(L.charAt(i))^Character.getNumericValue(res.charAt(i)));
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}
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return resAfterXor;
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}
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public String processDES(String IP,String[] sixteenkeys){
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int[] IPinverse={
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40,8,48,16,56,24,64,32,
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39,7,47,15,55,23,63,31,
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38,6,46,14,54,22,62,30,
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37,5,45,13,53,21,61,29,
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36,4,44,12,52,20,60,28,
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35,3,43,11,51,19,59,27,
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34,2,42,10,50,18,58,26,
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33,1,41,9,49,17,57,25
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};
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String L_0 = IP.substring(0,32);
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String R_0 = IP.substring(32);
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for(int i=0;i<16;i++){
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String L_temp = R_0;
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String R_temp = xorFun(L_0,R_0,sixteenkeys[i]);
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L_0 = L_temp;
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R_0 = R_temp;
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}
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String temp = new String();
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temp = R_0 + L_0;
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//IPinverse
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String final_vals = new String();
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for (int i=0;i<64;i++){
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final_vals = final_vals+temp.charAt(IPinverse[i]-1);
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}
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return final_vals;
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}
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public String PCOnePermutation(String key){
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int[] PC_1={
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57,49,41,33,25,17,9,
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1,58,50,42,34,26,18,
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10,2,59,51,43,35,27,
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19,11,3,60,52,44,36,
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63,55,47,39,31,23,15,
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7,62,54,46,38,30,22,
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14,6,61,53,45,37,29,
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21,13,5,28,20,12,4
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};
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String fiveSixkey = new String();
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for (int i=0;i<56;i++){
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fiveSixkey = fiveSixkey+key.charAt(PC_1[i]-1);
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}
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return fiveSixkey;
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}
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public String[] SixteenSubkeys(String key){
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String[] c = new String[16];
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String[] d = new String[16];
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String[] subKeys = new String[16];
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int[] PC_2={
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14,17,11,24,1,5,
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3,28,15,6,21,10,
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23,19,12,4,26,8,
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16,7,27,20,13,2,
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41,52,31,37,47,55,
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30,40,51,45,33,48,
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44,49,39,56,34,53,
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46,42,50,36,29,32
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};
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String fiveSixkey = PCOnePermutation(key);
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String c_0 = fiveSixkey.substring(0,fiveSixkey.length()/2);
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String d_0 = fiveSixkey.substring(fiveSixkey.length()/2);
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for(int i=0;i<16;i++){
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if(i==0 || i==1 || i==8 || i==15){
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c_0 = c_0.substring(1)+c_0.charAt(0);
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d_0 = d_0.substring(1)+d_0.charAt(0);
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}
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else{
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c_0 = c_0.substring(2)+c_0.charAt(0)+c_0.charAt(1);
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d_0 = d_0.substring(2)+d_0.charAt(0)+d_0.charAt(1);
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}
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c[i]=c_0;
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d[i]=d_0;
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}
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for(int j=0;j<16;j++){
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String tempKey = c[j]+d[j];
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String finalkey = new String();
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for (int i=0;i<48;i++){
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finalkey = finalkey + tempKey.charAt(PC_2[i]-1);
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}
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subKeys[j]=finalkey;
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}
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return subKeys;
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}
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public String HextoBinSplit(String cipher){
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int len = cipher.length();
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String res=new String();
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for (int i=0;i<len;i=i+2){
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res = res + HextoBin(cipher.substring(i, i+2));
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}
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return res;
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}
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public String HextoBin(String cipher){
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BigInteger hexVal = new BigInteger(cipher,16);
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String res = hexVal.toString(2);
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int len = hexVal.bitLength();
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if(len < 8)
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{
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for (int i=0;i<8-len;i++){
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res = "0"+res;
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}
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}
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return res;
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}
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}
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class desprog1
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{
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public static void main(String args[]){
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Scanner input = new Scanner(System.in);
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System.out.println(" ------ DES cryptosystem ------");
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System.out.println(" 1. Encryption");
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System.out.println(" 2. Decryption"+"\n");
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System.out.print(" Enter the choice: ");
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String choice = input.next();
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System.out.println("Enter Hexadecimal key:");
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String key = input.next();
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if(choice.equals("1")){
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System.out.println("Encryption selected");
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String ciphertext = new String();
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System.out.println("Enter plain:");
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String plain = input.next();
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DesCrypto ob = new DesCrypto();
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String res = ob.desEncryption(plain,key);
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System.out.println("Hexadecimal cipher: "+res.toUpperCase( ));
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}
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else if(choice.equals("2")){
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System.out.println("Decryption selected");
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try{
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String ciphertext = new String();
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System.out.println("Enter file name:");
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File filename = new File(input.next());
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Scanner filereader = new Scanner(filename);
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while(filereader.hasNextLine()){
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ciphertext += filereader.nextLine();
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}
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String cipherSubstrings[]=ciphertext.split("(?<=\\G.{16})");
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DesCrypto ob = new DesCrypto();
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//create file
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PrintWriter writer = new PrintWriter("desDecryptionResult.txt", "UTF-8");
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for(int i=0;i<cipherSubstrings.length;i++){
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String finalres=ob.desDecryption(cipherSubstrings[i],key);
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System.out.println(HexaToText(finalres));
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writer.print(HexaToText(finalres));
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}
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writer.close();
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}
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catch (Exception e){
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System.out.println(e);
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}
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}else{
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System.out.println("Select correct choise");
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}
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}
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public static String HexaToText(String hexaVals){
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String res = new String();
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for(int i=0;i<hexaVals.length();i+=2){
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String temp = hexaVals.substring(i,i+2);
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res += (char)Integer.parseInt(temp, 16);
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}
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return res;
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}
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}

‎DES, RSA, Rabin cryptosystem/doc/README.txt

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Requirements:
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java 1.7
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step1: make the working directory containing ciphertext files and submitted java files.
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step2: run the java file
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javac filename.java
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example:
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javac desprog1.java
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step3: run the java class
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java filename
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example:
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java desprog1
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step4: give respective inputs
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for desprog1.java check the file desDecryptionResult.txt produced by the program in current working directory.

‎DES, RSA, Rabin cryptosystem/doc/premhw2.pdf

590 KB
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