RSA Example

RSA.java

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package rsaexample;

/**
 *
 * @author touraj ebrahimi
 */
 
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;

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

public class Main {
       
    private static KeyPair keyPair;
 
    private static KeyPair initKeyPair() {
        try {
            keyPair = KeyPairGenerator.getInstance("RSA").generateKeyPair(); 
        } catch (NoSuchAlgorithmException e) {
            System.err.println("Algorithm not supported! " + e.getMessage() + "!");
        }
        return keyPair;
    }
     
  public static void main(String[] args) throws InvalidKeyException, IllegalBlockSizeException {
        initKeyPair();
        try {
            final Cipher cipher = Cipher.getInstance("RSA");     
            final String plaintext = "My Name Is Touraj...Hey Man";
 
            // ENCRYPT using the PUBLIC key
            cipher.init(Cipher.ENCRYPT_MODE, keyPair.getPublic());           
            byte[] encryptedBytes = cipher.doFinal(plaintext.getBytes()); 
            System.out.println("enc byte : " + encryptedBytes);
            //String chipertext = new String(Base64.getEncoder().encode(encryptedBytes));
//            String chipertext = DatatypeConverter.printBase64Binary(encryptedBytes);
            String chipertext = new String(encryptedBytes);
            System.out.println("encrypted (chipertext) = " + chipertext);
 
            // DECRYPT using the PRIVATE key
            cipher.init(Cipher.DECRYPT_MODE, keyPair.getPrivate()); 
            //byte[] ciphertextBytes = Base64.getDecoder().decode(chipertext.getBytes());
//            byte[] ciphertextBytes = DatatypeConverter.parseBase64Binary(chipertext);
            byte[] ciphertextBytes = chipertext.getBytes();
            byte[] decryptedBytes = cipher.doFinal(ciphertextBytes); 
            String decryptedString = new String(decryptedBytes);
            System.out.println("dec bytes : " + decryptedBytes);
            System.out.println("decrypted (plaintext) = " + decryptedString);
            
        } catch (NoSuchAlgorithmException e) {
            System.err.println("Algorithm not supported! " + e.getMessage() + "!");
        } catch (NoSuchPaddingException e) {
            System.err.println("Cipher cannot be created!");
            e.printStackTrace();
        } catch (BadPaddingException e) {
            System.err.println("An error occurred during the encryption!");
            e.printStackTrace();
        }
    }
}