You arrive at a hotel.

You check in.

A small card is handed to you.

You walk to your room, tap or insert the card, and the door unlocks.

It feels simple.

But behind that tiny piece of plastic is a sophisticated combination of electronics, encryption, sensors, communication systems, and security engineering.

Hotel key card systems are designed to provide millions of guests with fast, convenient, and secure access while allowing hotels to manage thousands of rooms at once.

We examine how hotel key cards communicate with door locks and how the system verifies whether a guest is authorized to enter a specific room.

Inside every electronic lock are carefully engineered components:

Sensors.

Microcontrollers.

Motors.

Batteries.

Locking mechanisms.

Communication systems. ...