code: public Packer useRSA(final Key rsaKeyForEncrypt, final Key rsaKeyForDecrypt)
  			throws NoSuchAlgorithmException, NoSuchPaddingException {
  		this.rsaCipher = Cipher.getInstance(ASYM_CIPHER_CHAIN_PADDING);
  		this.rsaKeyForEncrypt = rsaKeyForEncrypt;
  		this.rsaKeyForDecrypt = rsaKeyForDecrypt;
  		return this;
  	}
docs: Sets he usage of "RSA/ECB/PKCS1Padding" for encryption (default no)
  
  @param rsaKeyForEncrypt
  @param rsaKeyForDecrypt
  @return
  @throws NoSuchPaddingException
  @throws NoSuchAlgorithmException