RSA implementation using java

Question

I am implementing RSA in java I have encountered a code which is given below it is showing plaintext in numeric form after decrypting the plaintext, but I want it in simple engl

Answer 1

My RSA Class:

package com.infovale.cripto;

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Arrays;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

public class RSA {


static String kPublic = "";
static String kPrivate = "";

public RSA()
{

}


public String Encrypt(String plain) throws NoSuchAlgorithmException,
        NoSuchPaddingException, InvalidKeyException,
        IllegalBlockSizeException, BadPaddingException {

    String encrypted;
    byte[] encryptedBytes;      

    KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
    kpg.initialize(1024);
    KeyPair kp = kpg.genKeyPair();

    PublicKey publicKey = kp.getPublic();
    PrivateKey privateKey = kp.getPrivate();

    byte[] publicKeyBytes = publicKey.getEncoded();
    byte[] privateKeyBytes = privateKey.getEncoded();

    kPublic = bytesToString(publicKeyBytes);
    kPrivate = bytesToString(privateKeyBytes);

    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    encryptedBytes = cipher.doFinal(plain.getBytes());

    encrypted = bytesToString(encryptedBytes);
    return encrypted;

}

public String Decrypt(String result) throws NoSuchAlgorithmException,
        NoSuchPaddingException, InvalidKeyException,
        IllegalBlockSizeException, BadPaddingException {

    byte[] decryptedBytes;

    byte[] byteKeyPrivate = stringToBytes(kPrivate);

    KeyFactory kf = KeyFactory.getInstance("RSA");

    PrivateKey privateKey = null;
    try {

        privateKey = kf.generatePrivate(new PKCS8EncodedKeySpec(byteKeyPrivate));

    } catch (InvalidKeySpecException e) {
        e.printStackTrace();
    }

    String decrypted;

    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    decryptedBytes = cipher.doFinal(stringToBytes(result));
    decrypted = new String(decryptedBytes);
    return decrypted;

}

public String bytesToString(byte[] b) {
    byte[] b2 = new byte[b.length + 1];
    b2[0] = 1;
    System.arraycopy(b, 0, b2, 1, b.length);
    return new BigInteger(b2).toString(36);
}

public byte[] stringToBytes(String s) {
    byte[] b2 = new BigInteger(s, 36).toByteArray();
    return Arrays.copyOfRange(b2, 1, b2.length);
}
}