## Could Quantum Computers Put an End to Today’s Encryption Methods?

The thing about revolutions is that nobody can predict when they’ll come, they just do. **Quantum computing** is going to be that kind of revolution. Quantum computers are now almost out of the science phase. They are no longer theoretical, a simple abstraction. Now, it’s the engineering part that needs to be taken care of. However, the prevailing quantum computers are still a long way off the mark. Some of the prototypes are as large as rooms. But then, there was a point we could say the same about this current era of computer. And we all know how that panned out, right?

Nobody knows how many years it’s going to take for quantum computers to take over. Some say seven, some believe fifteen, and some go as far as twenty-five. Nobody knows. It’s like forecasting weather, but even less accurate. But one day, they’re going to be a reality and we must be prepared to embrace that reality. This takes us to the technology that protects our data and privacy on the internet – Encryption. Encryption is where the repercussions of quantum computing are going to be heard the most. We’ll get to that in a moment but let’s understand the concept of quantum computing first.

### WHAT IS QUANTUM COMPUTING?

The binary system is the foundation of today’s computers. They’re called ‘bits.’ All the information that today’s classical computers take, process and store is in the strings of 0’s and 1’s. Every piece of data has a combination of many 0’s and/or 1’s attached to it. Keep in mind that it can only be 0 or 1 at a time, not both. This is exactly where quantum computers differ from classical computers. Quantum computers use **Qubits** instead of Bits. It means that they run 0 & 1 at the same time. This is called **‘the principle of superposition’**. This duality has its roots in **quantum mechanics.**

A quantum computer with *n* qubits can be in 2* ^{n} *states at a time. So, a quantum computer with two qubits can be in four states simultaneously, three qubits in eight states and so on. As a result, highly complex problems that cannot be solved by classical computers can be solved by quantum computers.

Still confused? Let’s understand this with a small game.

Suppose we draw out four cards. Three of these cards are kings and one is a queen. Now, these cards are shuffled and put with their faces down. Ok, try to guess which of these four is a queen. How do you do it? You’ll pick one randomly and hope that it’s the right one. The probability here is only 25%. Now let’s feed this puzzle into a classical computer. Let’s assign a 0 to every king and 1 to the queen. The computer will use the same method as you did – trial and error. Research shows that a classical computer will need 2.5 attempts on average to solve this problem. But, had this data been fed into a quantum computer, it could have been solved in a single attempt (whoa!). This is because quantum computers can run more than one value simultaneously.

### Bit vs Qubit

Here the number of possibilities are only four. What if the number of possible solutions is a million digits long? Classic computers run out of steam for such problems. It might take them thousands of years to solve. For quantum computers, it’s just a matter of minutes.

Google’s quantum computer is 100 million times faster than your computer. Let that sink in for a moment!

### THIS IS HOW ENCRYPTION WILL BE AFFECTED

What are the prime factors of 21? Pretty easy, right? Now do the same for a number having thousands of digits. You’d probably say it’s impossible. Well, this is the concept behind the most widely accepted asymmetric encryption system, **RSA**.

### Impact of Quantum Computing

The RSA cryptosystem depends on this concept of prime-factorization. In RSA, the public key is obtained by multiplying prime-factors – the private keys. The public key is so large in length that it’s impossible to crack the private keys attached to it. There are 2^{112} possibilities to crack the private key. This is a certainly an enormous number – well and truly out of the reach of today’s computers. That’s the point behind every major encryption method used today. They’re designed in such a way that no computer can crack them. But when it comes to quantum computers, the story is entirely different as they’re fundamentally different from classic computers.

If we apply a quantum computer to crack the private key from the public key, it might be over before you even know it. Some say this could be done in as little as 100 seconds. It’s because a quantum computer can try so many combinations simultaneously. Thereby, posing an inescapable threat to today’s encryption methods. From protecting your passwords to safeguarding your credit card details – these encryption methods are used pretty much everywhere.

### WHAT DOES THE FUTURE HOLD?

First, there’s no need to panic. Quantum computers might be able to break some of the today’s encryption methods, but not all of them. Compared to the vastly used asymmetric encryption, symmetric encryption algorithms are somewhat safe from the threat of quantum computing. However, they might need a bit of sharpening. Dr. Michele Mosca, deputy director of the Institute for Quantum Computing at the University of Waterloo suggests **doubling the length of symmetric encryption keys** to safeguard them.

The ugly truth when it comes to quantum computing is that nobody knows when it becomes a reality. But cryptographers are fully aware of the danger and are looking to develop new techniques and algorithms. Unfortunately, research and development take time. How much? Again, nobody knows.

Such uncertainty on both sides makes this a fascinating and challenging contest.

Will quantum computers make encryption obsolete? Can scientists develop an impregnable encryption system in time? Will quantum encryption become a reality? Only time will tell.