Cryptography for Kids – Activities & Worksheets

Last Updated on 20/02/24 1

How to explain encryption to a child?

Cryptography is a serious science for technologists but can become a brain-teasing fun activity for kids. Parents and teachers try to introduce cryptography to kids not just to teach them cryptography but because cryptography is a great brain development tool too. It improves the reasoning and logical ability of a child.

Let’s explore everything about cryptography with fun cryptography activities and worksheets.
Note: The language of this post talks directly with the kids. Parents and teachers can use & execute this content the way they feel better.

Fun cryptography activity 1

I have a question: Can you read? Do you know reading? Haaa… silly question that is. You are already reading this post and I am asking if you can read it.

Ok, so I believe you can read, so please read the following.

You will be able to download this in worksheet format at the bottom of this post.
Na na… Don’t pronounce the alphabet. Read the words. Can you? Ah! So I won. Just a while back you said you can read. But you can’t above.

Ok Ok… I agree you can read, but then why can’t you read the above text?

Because this text is “Encrypted”, or in simple words, it’s morphed to make it secure.
This entire science of securing communication, so that only the sender and the intended receiver know the right message, is called “Cryptography”.

Fun cryptography activity 2: Securing a message

Do you know “Do Jasoos”? Jasoos Chinki and Jasoos Chintu. Two super spies they are. Both spies have a very challenging and important task with them.

What happened was that Jasoos Chinki has got a box of Kaju Katli and she had to keep it safe from others. But had to inform Jasoos Chintu where the box is.

Jasoos Chinki has prepared a message

“In The Top Drawer”

But how would they communicate this? Telling direct, or sending a chit is not an option.

So Jasoos Chinki has used a trick. She shifted the characters by 1.

What comes after I? That’s J. And after N? Correct, O. That way she sifted all the characters by one.

So the message became

“Jo Uif Upq Esbxfs”

So funny, no?

Here the original message is called “Plain Text”.

And the message that you generate after securing it is called “Cipher Text”.

This process of converting plain text to cipher text is called “Encryption”.

Now Jasoos chintu does the exact reverse of what jasoos chinki has done.

He will go one step back and put the previous characters of each of the characters of the cipher text.

So he gets to know that Kaju Katli is in the top drawer and he is ready to eat!

So what Jasoos chintu has done here? He has converted Cipher text to Plain text again.

And this process of converting a cipher text to plain text is called “Decryption”.

You will get many fun exercises to convert plain text to cipher text and cipher text to plain text or say Encryption and decryption in the cryptography worksheet at the bottom.

Fun cryptography activity 3: The concept of Key

This secure communication went well and both the jasoos were enjoying the Kaju Katli until one day when Hacku Hana “Interrupted” and “Cracked” their encryption.

Hacku Hana now knows where both the jasoos are keeping their Kaju Katli.

As Jasoos Chintu sensed this “Hacking”, they started changing the location of the box every time after use.

Jasoos Chinki will change the location and will send the location info in “Encrypted form” using cryptography.

But Hacky has got to know that they are increasing the character value by one every time to encrypt the message. So it was easy to know the location every time.

Jasoos were worried, but soon they found a better way to secure their message. They agreed to change the number of increments.

Someday they will increase the character by 4. The key will be 4. The message will be as below:

So B will become F.
B to F
J to N
P to T
And so on.

That number is called the “Key”. Sometimes they will keep the key 2 the other day it would be 7.

So Jasoos Chinki, Jasoos Chintu, and their box of Kaju Katli are safe, till Hacku Hanu understands this new “pattern” of cryptography used by them.

Let’s wait to know what happens with them. Till then you can try our cryptography worksheet.

Cryptography for kids worksheet

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