# Introduction to Quantum Cryptography

Hello friends, I hope you all are doing great. Today I am going to discuss and explain to you, Quantum Cryptography, in this article, you will learn what Quantum cryptography is and how the data was stored and transmitted by the first generation computers from one device to another.
It’s going to be a long series and today, I am posting its first lecture, so I’ll only cover the basics. I will briefly give you an overview of its history & we will understand How it has evolved in the past and now became an important part of digital world. So, let’s get started:
Quantum Cryptography
We know that digital data is always stored in bit format i.e. 0’s and 1’s but first generation computers stored the data using the method of Punch Tape (you can find the illustration below):

As you can see in above image, we have a pattern of punch holes. Here, holes are representing 0s and the plain surfaces are representing 1s. This type of data was authentic & reliable and there was almost zero percent chance of the data to get destroyed.

Then we entered the evolution of Hard Disk , which stores the data to bits in the electromagnetic form, which actually stores in the form of 1s and 0s. If you look at the picture carefully, you will see they have opposite polarity. In the hard disk, data is not as secured as in punch tape as you may get

In this 21st century, we are using Quantum Computer which is known as Q-bit. It exists in the form of superposition with the algorithms. So the data will be stored and transmitted through supercomputers.
Cryptography
As the means of communication are getting smarter, the security of sensitive or private data and information has become the highest risk. Therefore, the goal is to transmit the data and information safely from one server to another, this method is known as Cryptography.
In this method, the data and information are hidden between two servers, in a way that any third party/hacker unables to access them in an unauthorized way. (As we can see nowadays in our Whatsapp, the chats are end-to-end encrypted). We click it to disable the access of any third party to our data and to ensure that our chats are safe.
The cryptography can function through various methods to secure the data. The easiest philosophy is that both the sender and receiver have a codebook. So the sender, let’s name it Bob and the receiver is Alice:

Bob wants to send some information “A” to the receiver. ( Let’s suppose, “A” is equal to 18) .
We pick a code from our codebook which is 93, we will add this code in our data i.e. 18+93 = 111 and then we will subtract 100 from this product and we will get 11.
We send this 11 to the receiver, so we...

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