RSA Padding with Bouncy Castle on BlackBerry

Question

I'm using Bouncy Castle to encrypt strings to send them to my java web service where they are decrypted, when the message reaches the server I get a BadPaddingException, anybody know how to properly add the padding to an RSA Cipher with Bouncy Castle on J2ME?

This is the encryption code on the client:

public byte[] Encrypt(byte[] data)
  {
     RSAKeyParameters publicKey = new RSAKeyParameters(false, new BigInteger(_publicKeyModulus), new BigInteger(_publicKeyExponent));
     RSAEngine engine = new RSAEngine();
     engine.init(true, publicKey);

     byte[] output = engine.processBlock(data, 0, data.length);

     return output;
  } 

And this is how I decrypt it server side:

public byte[] Decrypt(byte[] data)
    {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] cipherData = cipher.doFinal(data);
            return cipherData;
        } catch (NoSuchAlgorithmException ex) {
            Logger.getLogger(EncryptorDecryptor.class.getName()).log(Level.SEVERE, null, ex);
        } catch (NoSuchPaddingException ex) {
            Logger.getLogger(EncryptorDecryptor.class.getName()).log(Level.SEVERE, null, ex);
        } catch(IllegalBlockSizeException ex) {
            Logger.getLogger(EncryptorDecryptor.class.getName()).log(Level.SEVERE, null, ex);
        } catch(InvalidKeyException ex) {
            Logger.getLogger(EncryptorDecryptor.class.getName()).log(Level.SEVERE, null, ex);
        } catch(BadPaddingException ex) {
            Logger.getLogger(EncryptorDecryptor.class.getName()).log(Level.SEVERE, null, ex);
        }

        return null;
    }

Answer 1

Instead of using RSAEngine directly use the PKCS1Encoding class and construct it with

PKCS1Encoding engine = new PKCS1Encoding(new RSAEngine());