Elgamal Encryption in java

package elgamal;

import java.util.Arrays;
import java.util.Vector;
import java.util.*;

/*
* Created on Mar 24, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class ElGamal {

/**
*
*/
public ElGamal() {
super();
// TODO Auto-generated constructor stub
}

public static void main(String[] args) {
Vector primeVector = new Vector();
Generator generator = new Generator();
int primeNumber = 0;
while (primeVector.isEmpty()) {
primeNumber = generator.createPrimeNumber(1000, 10000);
System.out.println("--------Prime Number--------");
System.out.println("Prime Number : " + primeNumber);
//Vector pnVector = generator.createPrimeNumberVector(1000, 2357);
primeVector = generator.createGenerator(primeNumber);
}
generator.initializeGenerator(Integer.parseInt(primeVector.elementAt(0)
.toString()), primeNumber);

System.out.println("--------Generator--------");
System.out.println("Generator : " + generator.getGenerator());
System.out.println("Prime Number : " + generator.getPrimeNumber());

// Create Encryption and Decryption keys
Keys keys = new Keys();
keys.initializeKeys(generator.getGenerator(), generator
.getPrimeNumber());
EncryptionKey encryptionKey = keys.getEncryptionKey();
DecryptionKey decryptionKey = keys.getDecryptionKey();

System.out.println("--------EncryptionKey--------");
System.out.println("Public Key : " + encryptionKey.getPublicKey());
System.out.println("Generator :" + encryptionKey.getGenerator());
System.out.println("Prime Number : " + encryptionKey.getPrimeNumber());

System.out.println("--------DecryptionKey--------");
System.out.println("Private Key : " + decryptionKey.getPrivateKey());
System.out.println("Prime Number : " + decryptionKey.getPrimeNumber());

// Initialize Encryption
String encryptionMessage = "suranga kulathunga";
Encryption encryption = new Encryption();
encryption.initializeEncryption(encryptionKey, encryptionMessage);
encryption.encrypt(encryptionMessage);
System.out.println("--------Encryption--------");
System.out.println("Encryption Message :" + encryptionMessage);
System.out.println("CipherTextOne : " + encryption.getCipherTextOne());
System.out.print("CipherTextTwo : ");
for (int i = 0; i < encryption.getCipherTextTwoArray().length; i++) {
System.out.print(encryption.getCipherTextTwoArray()[i] + " ");
}
System.out.println("");

// Initialize Decryption
Decryption decryption = new Decryption();
decryption.initializeDecryption(decryptionKey);
int[] mes = decryption.decrypt(encryption.getCipherTextOne(),
encryption.getCipherTextTwoArray());
System.out.println("--------Decryption--------");
String message = "";
int ASCII = 0;
System.out.print("Decryption Message :");
for (int i = 0; i < mes.length; i++) {
message += "" + ((char) mes[i]);
System.out.print(mes[i] + " ");
}
System.out.println("");

decryption.setMessage(message);
System.out.println("Final Message : " + decryption.getMessage());

}

}




package elgamal;
/*
* Created on Mar 31, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class Decryption {

private DecryptionKey decryptionKey = null;
private String message ="";
/**
*
*/
public Decryption() {
super();
// TODO Auto-generated constructor stub
}
/*
* Inverse of b mod a
*/
public long FindInverse(long a, long b){
long q =1;
long temp = 0;
long r = 1;
long sign = 1;
long store = a;
long s =0;

while(b!=0){
q=a/b;
temp = r;
r = temp*q+s;
s= temp;
temp = b;
b = a- q*temp;
a = temp;
sign =- sign;

}
long answer = (r-(sign*s))%store;
return answer;
}
public void initializeDecryption(DecryptionKey decryptionKey){
this.decryptionKey =decryptionKey;
}
public DecryptionKey getDecryptionKey(){
if(decryptionKey != null){
return this.decryptionKey;
}else{
this.decryptionKey = new DecryptionKey ();
return this.decryptionKey;
}
}
public int getModValue(int tempGenerator , int modNumber, int power){
int ReturnModValue = 1;
for(int i =0;i < power; i++){
ReturnModValue =(ReturnModValue*tempGenerator) % (modNumber);
}
return ReturnModValue;
}

public int[] decrypt(int cipherTextOne , int [] cipherTextTwoArray){
int []InverseValue2 = new int[cipherTextTwoArray.length];
long InverseValue = FindInverse(this.decryptionKey.getPrimeNumber(),cipherTextOne);
int InverseValue1 =getModValue((int)InverseValue,this.decryptionKey.getPrimeNumber(),this.decryptionKey.getPrivateKey());
for(int i =0; i InverseValue2[i] = (InverseValue1*cipherTextTwoArray[i])%decryptionKey.getPrimeNumber();
}
return InverseValue2;
}
public String getMessage(){
return this.message;
}

public void setMessage(String message){
this.message = message;
}
}



package elgamal;
/*
* Created on Mar 27, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class CipherText {

/**
*
*/

private int CipherTextOne = 0;
private int CipherTextTwo = 0;

public CipherText() {
}

public void setCipherTextOne(int CipherTextOne ){
this.CipherTextOne = CipherTextOne;
}
public void setCipherTextTwo(int CipherTextTwo ){
this.CipherTextTwo = CipherTextTwo;
}
public int getCipherTextOne(){
return this.CipherTextOne;
}
public int getCipherTextTwo(){
return this.CipherTextTwo;
}
}


package elgamal;

/*
* Created on Mar 28, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class DecryptionKey {

/**
*
*/
private int primeNumber = 0;
private int privateKey = 0;
public DecryptionKey() {

}

public int getPrivateKey(){
return privateKey;
}
public int getPrimeNumber(){
return primeNumber;
}
public void setPrivateKey(int privateKey){
this.privateKey = privateKey;
}
public void setPrimeNumber(int primeNumber){
this.primeNumber = primeNumber;
}


}


package elgamal;

/*
* Created on Mar 28, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class Encryption {

/**
*
*/
private int randomNumber = 0;
private int cipherTextOne = 0;
private int cipherTextTwo = 0;
private int [] cipherTextTwoArray = null;
private String Message = "";
private EncryptionKey encryptionKey = new EncryptionKey();
public Encryption() {
super();
// TODO Auto-generated constructor stub
}
public void createCipherTextOne(){
int primeNumber = this.encryptionKey.getPrimeNumber();
int generator= this.encryptionKey.getGenerator();
this.cipherTextOne = getModValue(generator,primeNumber,randomNumber);
//this.cipherTextOne =(Math.pow(generator,randomNumber))%publicKey;
}

public int createCipherTextTwo(int message){
int primeNumber = this.encryptionKey.getPrimeNumber();
int generator= this.encryptionKey.getGenerator();
int randomNumber =this.randomNumber;
//int powerValue = randomNumber*primeNumber;
int powerValue = getModValue(encryptionKey.getPublicKey(),primeNumber,randomNumber);
this.cipherTextTwo = (message*powerValue)%primeNumber;
//this.cipherTextTwo = (message*getMadValue(generator,primeNumber,randomNumber))%primeNumber;

//this.cipherTextOne =(Math.pow(generator,randomNumber))%publicKey;
return cipherTextTwo;
}

public void initializeEncryption(EncryptionKey encryptionKey,String encryptionMessage){
this.encryptionKey =encryptionKey;
this.randomNumber =(int)((this.encryptionKey.getPrimeNumber()-2)*(Math.random()));
this.Message = encryptionMessage;
}
public int getModValue(int tempGenerator , int modNumber, int power){
int ReturnModValue = 1;
for(int i =0;i < power; i++){
ReturnModValue =(ReturnModValue*tempGenerator) % (modNumber);
}
return ReturnModValue;
}
public int getCipherTextOne(){
return this.cipherTextOne;
}

public int getCipherTextTwo(){
return this.cipherTextTwo;
}

public int[] getCipherTextTwoArray(){
return this.cipherTextTwoArray;
}

public void encrypt(String Message){
this.createCipherTextOne();
int length = Message.length();
//int [] Ascii = new int[Message.];
cipherTextTwoArray = new int[length];
for (int i = 0 ; i cipherTextTwoArray[i] = this.createCipherTextTwo((int)Message.charAt(i));
}
}
}



package elgamal;

/*
* Created on Mar 28, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class EncryptionKey {

/**
*
*/
private int primeNumber = 0;
private int publicKey = 0;
private int generator = 0;
public EncryptionKey() {
super();
// TODO Auto-generated constructor stub
}

public int getPrimeNumber(){
return primeNumber;
}
public int getPublicKey(){
return publicKey;
}
public int getGenerator(){
return generator;
}

public void setPrimeNumber(int primeNumber){
this.primeNumber = primeNumber;
}

public void setPublicKey(int publicKey){
this.publicKey = publicKey;
}
public void setGenerator(int generator){
this.generator = generator;
}

}



package elgamal;

import java.util.Vector;

/*
* Created on Mar 26, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class Generator {

private int primeNumber = 0;
private int generator = 0;
/**
*
*/
public Generator() {
super();
// TODO Auto-generated constructor stub
}
public Vector createGenerator(int primeNumber){
Vector aa = new Vector();
int tempGenerator = 0;
for ( tempGenerator =2 ; tempGenerator boolean valueGenerated = false;
int[] TempArray = new int[primeNumber - 1];
int ReturnModValue = 1;
for (int tempVal = 1; tempVal < primeNumber; tempVal++) {

// Return the Mod value

ReturnModValue = getModValue(tempGenerator, primeNumber,
tempVal,ReturnModValue);

// Check the Mod value , if it is equal to 1 and not the last number
if(ReturnModValue == 1 && tempVal!=primeNumber-1){
break;
}

// Compare it with other mod values
boolean temp = compareValue(TempArray, ReturnModValue , tempVal);

// Add the Mod values to a array
TempArray[tempVal - 1] = ReturnModValue;

if (temp == true) {
break;
}
// If this is a generator set the flag true
if(tempVal == primeNumber-1 && TempArray[tempVal-1]==1){
valueGenerated= true;
break;
}
}

// Add the Generator to the Vetor
if(valueGenerated==true){
aa.addElement(String.valueOf(tempGenerator));
break;
}
}
return aa;
//return tempGenerator;
}
public int getModValue(int tempGenerator , int primeNumber, int tempVal, int ReturnModValue){
int anu =(ReturnModValue*tempGenerator) % (primeNumber);
return anu;
}
public boolean compareValue(int TempArray[],int ReturnModValue, int tempVal){
for ( int i =0 ; i if(TempArray[i] ==ReturnModValue ){
return true;
}
}
return false;
}

public int createPrimeNumber(int StartNumber , int EndNumber){
double x =0;
while (true){
double PrimeNumber =StartNumber+ (EndNumber - StartNumber)*Math.random();
int PrimeNumber1 =(int)PrimeNumber;
//double x = (Math.pow(2,PrimeNumber1-1))%PrimeNumber1;
x = getTotalModValue(2,PrimeNumber1,PrimeNumber1-1);
if(x==1){
return PrimeNumber1;
}
}

}
public Vector createPrimeNumberVector(int StartNumber , int EndNumber){
Vector aa = new Vector();
double x =0;
double y =0;
double xfinal =0;
int ans =0;
for ( int i =StartNumber ; i<=EndNumber ; i++){
// int index = i/1000;
// x = (Math.pow(2,1000))%i;
// y = (Math.pow(2,i-1-(index*1000)))%i;
// xfinal =Math.pow(x,index);
// ans = (xfinal*y)%i;
ans = getTotalModValue(2,i,i-1);
if(ans==1){
aa.addElement(String.valueOf(i));
}
}
return aa;
}
public int getTotalModValue(int tempGenerator , int modNumber, int power){
int ReturnModValue = 1;
for(int i =0;i < power; i++){
ReturnModValue =(ReturnModValue*tempGenerator) % (modNumber);
}
return ReturnModValue;
}
public void setPrimeNumber(int primeNumber){
this.primeNumber = primeNumber;
}
public void setGenerator(int generator){
this.generator = generator;
}
public int getPrimeNumber(){
return primeNumber;
}
public int getGenerator(){
return generator;
}
public void initializeGenerator(int generator,int primeNumber){
setPrimeNumber(primeNumber);
setGenerator(generator);
}
}



package elgamal;

/*
* Created on Mar 26, 2008
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

/**
* @author suranga kulathunga
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class Keys {

/**
*
*/
public Keys() {

}

private int primeNumber = 0;
private int privateKey = 0;
private int publicKey = 0;
private int generator = 0;

public int getPrivateKey(){
return privateKey;
}
public int getPrimeNumber(){
return primeNumber;
}
public int getPublicKey(){
return publicKey;
}
public int getGenerator(){
return generator;
}

public void setPrimeNumber(int primeNumber){
this.primeNumber = primeNumber;
}
public void setGenerator(int generator){
this.generator = generator;
}
public void setPrivatePublicKeys(int privateKey,int primeNumber){
this.privateKey = privateKey;
//this.publicKey = (Math.pow(this.generator,privateKey))%primeNumber;
this.publicKey = getMadValue(generator,primeNumber,privateKey);
}
public void initializeKeys(int generator,int primeNumber){
setPrimeNumber(primeNumber);
setGenerator(generator);
this.privateKey =(int)((primeNumber-2)*(Math.random()));
this.publicKey = getMadValue(generator,primeNumber,privateKey);
//this.publicKey = (Math.pow(this.generator,privateKey))%primeNumber;
}
public EncryptionKey getEncryptionKey(){
EncryptionKey publicKey = new EncryptionKey();
publicKey.setGenerator(this.generator);
publicKey.setPrimeNumber(this.primeNumber);
publicKey.setPublicKey(this.publicKey);
return publicKey;
}

public DecryptionKey getDecryptionKey(){
DecryptionKey privateKey = new DecryptionKey();
privateKey.setPrivateKey(this.privateKey);
privateKey.setPrimeNumber(this.primeNumber);
return privateKey;
}
public int getMadValue(int tempGenerator , int modNumber, int power){
int ReturnModValue = 1;
for(int i =0;i < power; i++){
ReturnModValue =(ReturnModValue*tempGenerator) % (modNumber);
}
return ReturnModValue;
}
}