Java rsa шифрование

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.Security;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
 
import javax.crypto.Cipher;
 
public class MainClass {
  public static void main(String[] args) throws Exception {
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
 
    byte[] input = new byte[] { (byte) 0xbe, (byte) 0xef };
    Cipher cipher = Cipher.getInstance("RSA/None/NoPadding", "BC");
 
    KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
    RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(
        "12345678", 16), new BigInteger("11", 16));
    RSAPrivateKeySpec privKeySpec = new RSAPrivateKeySpec(new BigInteger(
        "12345678", 16), new BigInteger("12345678",
        16));
 
    RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubKeySpec);
    RSAPrivateKey privKey = (RSAPrivateKey) keyFactory.generatePrivate(privKeySpec);
 
    cipher.init(Cipher.ENCRYPT_MODE, pubKey);
 
    byte[] cipherText = cipher.doFinal(input);
    System.out.println("cipher: " + new String(cipherText));
 
    cipher.init(Cipher.DECRYPT_MODE, privKey);
    byte[] plainText = cipher.doFinal(cipherText);
    System.out.println("plain : " + new String(plainText));
  }
}