code: private RSAPrivateKeySpec getRSAPrivateKeySpec() {
  
          return new RSAPrivateCrtKeySpec(toBigInteger(n), toBigInteger(e), toBigInteger(d), toBigInteger(p),
                  toBigInteger(q), toBigInteger(dp), toBigInteger(dq), toBigInteger(qi));
      }
docs: Get the RSA private key spec value.
  
  @return the RSA private key spec value