Galois/Counter Mode

Galois/Counter mode, or GCM for short, is a way of keeping things safe and protected on the internet. It’s like a super secret code that only certain people can understand.

Imagine you have a special box and you want to send it to your friend. But you don’t want anyone else to be able to open the box and see what's inside. So you put a lock on the box. The lock has a special key that only your friend has, so only they can open the box.

GCM works kind of like that lock. It uses a secret code to lock up information so that only certain people can read it. But it also goes a step further than just a lock. It also has a special way of checking if someone has messed with the information before it gets to your friend.

This checking happens using something called a “Galois field”. A Galois field is a special math concept that helps GCM make sure that nobody has tampered with the information before it gets to your friend. It’s like a protective shield that keeps the information safe from any bad guys who might try to sneak in and change things.

So, in short, GCM is a special way of keeping information safe and secure when it’s being sent over the internet. It uses a secret code to lock it up and a Galois field to protect it from bad guys who might try to change it.