Door lock with password pin

There are a lot of solutions regarding this topic, but I couldn’t find any specific using nodered and mqqt server.

I’ve implemented a door lock in my house with two rfid. One internal and other external. I also took out the padlock. The only way to open it is using a 12V over the coil.

For that I used an Arduino Uno, which I decided to upgrade to an ESP32 using MicroPython. From time to time, Arduino Uno freezes due Software Serial. ESP32 has 3 UART ports, which I hope can increase reliability.

Since it already has WiFi, I did a simple subscribe and a button to open the door as well. Get in and out with the smartphone. Unfortunately, that’s not safe at all. Mainly because of my kids.

My goal is to implement a field where you must feel a 6 digit pin and submit.
Esp32 check the pin and decide if open or not.

What do you suggest, as simple and direct solution for that?

I was just considering using form, but I still need to learn about How nodered deal with POST and so on. In other words, I need to be sure which is the best solution to guide the efforts for.

I'm now using form with number type. When I open my smartphone, it open the number pad only. Great! However, how do I limit the number of characters and hash the password?