Java - RSA Algorithm

	import java.security.InvalidKeyException;
	import java.security.KeyPair;
	import java.security.KeyPairGenerator;
	import java.security.NoSuchAlgorithmException;
	import java.security.PrivateKey;
	import java.security.PublicKey;
	import javax.crypto.BadPaddingException;
	import javax.crypto.Cipher;
	import javax.crypto.IllegalBlockSizeException;
	import javax.crypto.NoSuchPaddingException;

	/**
	 *
	 * @author dhanoopbhaskar
	 */
	public class RSAAlgorithm {
	   
	    private KeyPairGenerator keyPairGenerator = null;
	    private PrivateKey privateKey = null;
	    private PublicKey publicKey = null;
	    Cipher cipher = null;
	   
	    public RSAAlgorithm() {
	        try {
	            /**
	             * Create RSA key pairs
	             * - private key
	             * - public key
	             */
	            keyPairGenerator = KeyPairGenerator.getInstance("RSA");
	            keyPairGenerator.initialize(512); //512 is the key size
	            KeyPair keyPair = keyPairGenerator.generateKeyPair();
	            privateKey = keyPair.getPrivate();
	            publicKey = keyPair.getPublic();
	            /**
	             * Create an instance of cipher
	             */
	            cipher = Cipher.getInstance("RSA");
	        } catch (NoSuchPaddingException ex) {
	            System.out.println(ex);
	        } catch (NoSuchAlgorithmException ex) {
	            System.out.println(ex);
	        }
	    }
	   
	    /**
	     *
	     * @param plainText
	     * @return cipherText
	     */
	    public byte[] encryptText(String plainText) {
	        byte[] cipherText = null;
	        try {
	            /**
	             * Initialize the cipher for encryption
	             */
	            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
	            /**
	             * Convert the text string to byte format
	             */
	            byte[] plainBytes = plainText.getBytes();
	            /**
	             * Perform encryption with method doFinal()
	             */
	            cipherText = cipher.doFinal(plainBytes);           
	        } catch (IllegalBlockSizeException ex) {
	            System.out.println(ex);
	        } catch (BadPaddingException ex) {
	            System.out.println(ex);
	        } catch (InvalidKeyException ex) {
	            System.out.println(ex);
	        }
	       
	        return cipherText;
	    }
	   
	    /**
	     *
	     * @param cipherText
	     * @return plainText
	     */
	    public String decryptText(byte[] cipherText) {
	        String plainText = null;
	        try {
	            /**
	             * Initialize the cipher for decryption
	             */
	            cipher.init(Cipher.DECRYPT_MODE, privateKey);           
	            /**
	             * Perform decryption with method doFinal()
	             */
	            byte[] plainBytes = cipher.doFinal(cipherText);
	            /**
	             * Convert encrypted text to string format
	             */
	            plainText = new String(plainBytes);
	        } catch (IllegalBlockSizeException ex) {
	            System.out.println(ex);
	        } catch (BadPaddingException ex) {
	            System.out.println(ex);
	        } catch (InvalidKeyException ex) {
	            System.out.println(ex);
	        }
	       
	        return plainText;
	    }
	   
	    public static void main(String[] args) {
	        RSAAlgorithm rsaAlgorithm = new RSAAlgorithm();
	        String textToEncrypt = "RSA Algorithm";
	        System.out.println("Text before Encryption: " + textToEncrypt);
	        byte[] cipherText = rsaAlgorithm.encryptText(textToEncrypt);
	        System.out.println("Cipher Text [bytes]: " + cipherText);       
	        String textDecrypted = rsaAlgorithm.decryptText(cipherText);
	        System.out.println("Text after Decryption: " + textDecrypted);
	    }
	}