Encryption.java

/**Author rajeevkallalu
Invictus@AGI*/
package com.sanfoundry.setandstring;
 
import static com.sanfoundry.setandstring.RSA.bytesToString;
import java.math.BigInteger;
import java.util.Random;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.xml.bind.DatatypeConverter;


 class AES extends RSA {
 
/**
     * gets the AES encryption key. In your actual programs, this should be safely
     * stored.
     * @return
     * @throws Exception 
     */
    public static SecretKey getSecretEncryptionKey() throws Exception{
        KeyGenerator generator = KeyGenerator.getInstance("AES");
        generator.init(128); // The AES key size in number of bits
        SecretKey secKey = generator.generateKey();
        return secKey;
    }
    
    /**
     * Encrypts plainText in AES using the secret key
     * @param plainText
     * @param secKey
     * @return
     * @throws Exception 
     */
    public static byte[] encryptText(String plainText,SecretKey secKey) throws Exception{
		// AES defaults to AES/ECB/PKCS5Padding in Java 7
        Cipher aesCipher = Cipher.getInstance("AES");
        aesCipher.init(Cipher.ENCRYPT_MODE, secKey);
        byte[] byteCipherText = aesCipher.doFinal(plainText.getBytes());
        return byteCipherText;
    }
    
    protected static String  bytesToHex(byte[] hash) {
        return DatatypeConverter.printHexBinary(hash);
    }
    public static String decryptText(byte[] byteCipherText, SecretKey secKey) throws Exception {
		// AES defaults to AES/ECB/PKCS5Padding in Java 7
        Cipher aesCipher = Cipher.getInstance("AES");
        aesCipher.init(Cipher.DECRYPT_MODE, secKey);
        byte[] bytePlainText = aesCipher.doFinal(byteCipherText);
        return new String(bytePlainText);
    }
    

}
 class RSA {

 private BigInteger p;
    private BigInteger q;
    private BigInteger N;
    private BigInteger phi;
    private BigInteger e;
    private BigInteger d;
    private int        bitlength = 1024;
    private Random     r;
 
    public RSA()
    {
        r = new Random();
        p = BigInteger.probablePrime(bitlength, r);
        q = BigInteger.probablePrime(bitlength, r);
        N = p.multiply(q);
        phi = p.subtract(BigInteger.ONE).multiply(q.subtract(BigInteger.ONE));
        e = BigInteger.probablePrime(bitlength / 2, r);
        while (phi.gcd(e).compareTo(BigInteger.ONE) > 0 && e.compareTo(phi) < 0)
        {
            e.add(BigInteger.ONE);
        }
        d = e.modInverse(phi);
    }
 
    public RSA(BigInteger e, BigInteger d, BigInteger N)
    {
        this.e = e;
        this.d = d;
        this.N = N;
    }
 
   protected static String bytesToString(byte[] encrypted)
    {
        String test = "";
        for (byte b : encrypted)
        {
            test += Byte.toString(b);
        }
        return test;
    }
 
    // Encrypt message
    public byte[] encrypt(byte[] message)
    {
        return (new BigInteger(message)).modPow(e, N).toByteArray();
    }
 
    // Decrypt message
    public byte[] decrypt(byte[] message)
    {
        return (new BigInteger(message)).modPow(d, N).toByteArray();
    }
    
} 

public class Encryption extends AES{
        public static void main(String[] args) throws Exception {
    
		System.out.println("enter text");
        BufferedReader buffer=new BufferedReader(new InputStreamReader(System.in));
        String plainText=buffer.readLine();
        SecretKey secKey = getSecretEncryptionKey();
        byte[] cipherText = encryptText(plainText, secKey);
        //String decryptedText = decryptText(cipherText, secKey);
        System.out.println("Original Text:" + plainText);
        System.out.println("AES Key (Hex Form):"+bytesToHex(secKey.getEncoded()));
        System.out.println("Encrypted Text (Hex Form):"+bytesToHex(cipherText));
        //RSA
         RSA rsa = new RSA();
       //byte[] teststring;
        //teststring=cipherText;
        // encrypt
        byte[] encrypted = rsa.encrypt(cipherText);
        System.out.println("RSA encrypted data:"+encrypted);
        // decrypt
        byte[] decrypted = rsa.decrypt(encrypted);
        System.out.println("RSA Decrypting Bytes: " + bytesToString(decrypted));
        System.out.println("Decrypted String: " + new String(decrypted));
        
        String decryptedText = decryptText(cipherText, secKey);
        System.out.println("Descrypted Text:"+decryptedText);
        
        
        
    }
}