How quantum computing impacts cryptography

Written by janvi

cybersecurity blogger and hacking enthusiastic

November 26, 2018

A classical computer encodes data in binary digits that can only be a “1” or a “0” which we refer as bits whereas a quantum computer uses “qubits”. A single qubit can encode more than two states. And the Quantum computers that exist today can’t perform more complex operations than simple tasks such as factoring 12 into 4×3, so they’re pretty useless.  But a future quantum computer might be large and reliable enough to perform operations involving millions of quantum bits in order to break cryptographic algorithms widely used today.

qubits can break cryptographic algorithms which are widely used today

Many governments, universities, and companies around the world are racing to build a quantum computer that is large and reliable enough by using a variety of different experimental techniques. Due to the unique properties of qubits, it is possible to create algorithms that run significantly faster on a quantum computer than a normal computer.

IT security relies alone on public key and encryption cryptography, which are essential to protect secret electronic information and also for e-commerce. These techniques are based on mathematical algorithms which are very difficult to break. Modern algorithms with suitable key lengths are not susceptible to any kind of brute force attack even with massive amounts of computing power sometimes it would take centuries or even longer than the lifetime of the universe to break.

But with the help of quantum computers, it is possible to create unique algorithms to break these algorithms. A quantum computer which is large and reliable enough can break nearly every practical application of cryptography in use today making all the digital applications that we rely on in our daily lives totally insecure.

So what should we do now? Should we worry? Probably not as it is a global problem and of course there are many people working on this. But you should ignore it. We should Keep an eye on the progress of quantum computing and on the development of quantum-resistant algorithms and also ensure your applications and infrastructures are upgradable.

The only good news is the large-scale quantum computers are not feasible now. Moreover, viable quantum computers will initially be very expensive so initially, only governments will be able to afford them and they will only have enough capacity to attack the most valuable secrets of other countries. But in future, this capability may trickle down to organized criminals, but again they will only have the capacity able to attack the most lucrative targets.


In today’s world information plays a particularly important role and the transmission, storage of data must be maximally secure. Though Quantum computers pose a significant risk to both conventional public key algorithms and symmetric key algorithms it can only be reduced by the introduction of cryptographic schemes resistant to quantum computing.

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