A few weeks ago, I was in a meeting at work where we were discussing quantum resistant cryptographic algorithms and how quickly this area of technology is evolving. The discussing included a mix of people with different backgrounds, security engineers, IT specialists, project managers, and a few architects. Conversations like that tend to become pretty technical pretty quickly.
After the meeting wrapped up, one of my colleagues (who doesn’t work directly in cybersecurity) came over and asked a simple question.
“So what exactly is quantum computing?“
I gave him a simple and short explanation, the kind your give when someone just wants the high level idea. But the conversation stuck with me afterward. Quantum computing is a term we hear constantly in the tech world. It shows up in news articles, industry conferences, research papers, and of course in vendor marketing. Most people generally understand that it refers to extremely powerful computers capable of solving problems traditional machines cannot.
But what I realized during that conversation is that very few people actually understand the basic principles behind it. The term has become familiar, but the concepts behind it are still a bit mysterious to many professionals.
To make the topic easier to follow (and to write), I decided to split into three parts:
- Post 1 (This article) – A practical introduction to quantum computing and the fundamentals of modern cryptography.
- Post 2 – Why quantum computing has the potential to break many of the cryptographic algorithms we rely on today.
- Part3 – The emerging world of quantum resistant cryptography and how organizations can begin preparing for the transition.
I am not an expert on the topic but as a cybersecurity professional I am aware of it. I will do my best to help navigate IT generalists and non IT professionals on the above three points.
A New Frontier in Computing
Every few decades, computing goes through a major shift.
- The invention of the transistor made modern computing possible.
- The internet connected the world.
- Cloud computing changed how infrastructure is built and operated.
- AI has begun transforming how we interact with data
Quantum computing could very well be the next major shift.
Unlike improvements in the processor speed or storage capacity, quantum computing represents an entirely different approach to computation. Instead of simply building faster versions of the computers we already have, researchers are designing machines that operate using the principles of quantum mechanics.
For certain types of problems, these machines could perform calculations that would take classical computers thousands or even millions of years . That potential is exciting for fields such as medicine, chemistry, logistics, etc. But it also raises serious questions in another area, cybersecurity.
Many of the encryption systems that are used on a daily basis and that protect our digital infrastructure rely on mathematical problems that are extremely difficult for classical computers to solve. Quantum computing could change that assumption.
Understanding Quantum Computing
Traditional computer process information using bits. A bit represents one of two values (or states), 0 or 1. Every file, image, website, or application running on your laptop ultimately boils down to long sequences of these zeros and ones, and therefore the nomenclature of binary values or binary computing.
Quantum computers use a different unit of information known as qubit, short of quantum bit. What makes a qubit unique is that it can exist in multiple states at the same time, this is a property of quantum physics and is known as superposition. For example, if we stay in our binary computing, a qubit can be in a superposition of 0 AND 1, allowing quantum computers to process a vast number of possibilities at once.
This is a strange concept to digest at first, but a common analogy is a spinning coin. When a coin is resting on a table, it is clearly heads or tails. But when it is spinning, it is not very clear one or the other, it exists in a mixture of both possibilities until it lands. Qubits behave in a similar way. Instead of representing only 0 or 1, they can represent a combination of both states simultaneously.
Another important property of quantum systems is entanglement. When qubits become “entangled”, the state of one qubit becomes directly related to the state of another one. Changing one affects the other instantly, even if they are physically separated. As an example that is easy to digest I recommend you to check “Quantum Computing Explained Through the Spider-verse“, a post in Medium.com that is fun where Riany Mello, the post author explains it really well.
These two properties, superposition and entanglement allow quantum computers to process information in ways that classical computers cannot. Instead of evaluation possible solutions one at a time, quantum systems can explore many possibilities simultaneously and therefore make these machines exponentially more powerful processing wise than our regular computers.
How Quantum Computers Actually Work
Building a quantum computer is far from simple. Unlike traditional processors, qubits are extremely sensitive to their environment. Even small disturbances such as temperature changes, electromagnetic interference, or vibrations can disrupt their quantum state.
To maintain stability, many quantum systems operate at temperatures extremely close to absolute zero (approx -273.15 °C and -459.6°F). The processors are often housed in large cryogenic chambers that look more like scientific instruments. At the moment there are different technologies explored to implement qubits:
- Super conducting circuits
- Trapped ions
- Photonic quantum systems
Inside the processor, operations known as quantum gates manipulate qubits in a controlled way. These gates adjust the probability states of qubits and guide the system toward the correct computational result. However, because quantum states are fragile, researchers must also deal with quantum error correction, which is an entire field of study on its own.
Today’s quantum machines are still considered experimental, but progress has been steady. Each year brings improvements in stability, qubit counts, and overall performance.
Why Cryptography Matters?
To understand why cybersecurity professionals are paying a close attention to quantum computing, we need to take a step back and look at how cryptography works.
Cryptography is what protects information when it travels across networks or is stored digitally. Without it, activities such as online banking, secure messaging, and digital identity would not be possible. Most modern cryptographic systems fall into two main categories: Symmetric Encryption, and Asymmetric Encryption.
Symmetric Encryption uses the same secret key to both encrypt and decrypt information. Examples include algorithms like:
- AES (Advances Encryption Standard) which is a variant of the Rijndael block cipher
- ChaCha20
These algorithms are extremely efficient and are commonly used to encrypt large amounts of data. Their security relies on the size of the key space. For instance, AES-256 has 2^256 possible keys (this number is as large as the total number of atoms in the observable universe), making brute force attacks practically impossible with current computing power.
Asymmetric Encryption or Public Key Cryptography works differently:
Instead of one shared key that both encrypts and decrypts messages like in symmetric encryption, Asymmetric encryption uses two keys:
- A public key, which anyone can use to encrypt information
- A private key, which only the owner possesses to decrypt it
The system makes it possible for two parties to communicate securely even if they have never exchanges secrets before. Some of the most widely used Public Key algorithms include:
These algorithms rely on mathematical problems that are easy to compute in one direction but extremely difficult to reverse. For example, multiplying two large prime numbers together is straightforward, but determining the original primes from the resulting number (factoring) becomes incredibly difficult as the numbers grow larger.
This asymmetry form the basis of much of the internet’s security infrastructure.
The Assumption Behind Modern Encryption
Modern Cryptography is built on an important assumption: certain mathematical problems are computationally impractical to solve.
With today’s computers, breaking strong encryption through brute force (attempting every possible key combination) would require an unrealistic amount of time that is often measures in thousands or million of years. As long as this assumption holds, encrypted data remains secure.
But what happens if a new type of computer is developed that can solve these problems far more efficiently? That is the possibility ys why the cybersecurity community is watching the progress of quantum computing so closely.
Where Cryptography Shows Up in Everyday Tech
Cryptography is deeply embedded in modern digital systems, often in ways that we rarely think about. Cryptography protects:
- Secure web connections via HTTPS
- Online banking transactions
- Messaging applications with end-to-end encryption
- Digital signatures used in software updates
- Blockchain transactions and cryptocurrency wallets
- many more
In various ways, the trust that we place in digital systems is built directly on cryptographic algorithms. This is why understanding how those algorithms works, and where their limits may lie, is essential to continue on this “trusted” state.
Preparing for next post:
Quantum computing represents both an extraordinary technological breakthrough and a potential challenge to existing security models. In this first post, we covered the foundational concepts:
- What quantum computing is
- How quantum computers differ from classical systems
- How modern cryptography protects digital communications
In the next post, I will cover one step further and we will examine how certain quantum algorithms (specially Shor’s algorithms and Grover’s algorithms) could potentially weaken or break many of the cryptographic systems currently used across the internet.
Understanding that risk is the first step toward preparing for the post-quantum cryptographic world that researchers and security teams are already beginning to design.
Final thoughts
Cryptography has protected the digital world for decades by relying on mathematical problems that are extremely difficult to solve. Quantum computing introduces a new computational model that may eventually change the balance of the equation. The challenge now is not quite simply understanding the technology, but ensuring that the systems we build today remain secure in the decades ahead.
References and further reading
National Institute of Standards and Technology (NIST)
Post-Quantum Cryptography Project
https://csrc.nist.gov/projects/post-quantum-cryptographyIBM Quantum
What is Quantum Computing?
https://www.ibm.com/quantum/what-is-quantum-computingGoogle Quantum AI
Quantum Computing Overview
https://quantumai.google/Microsoft Azure Quantum
Introduction to Quantum Computing
https://learn.microsoft.com/en-us/azure/quantum/overviewCloudflare
The State of Post-Quantum Cryptography
https://www.cloudflare.com/learning/ssl/what-is-post-quantum-cryptography/Scott Aaronson
Quantum Computing Since Democritus (Book)Nielsen, M. & Chuang, I.
Quantum Computation and Quantum Information (Cambridge University Press)Shor, P. (1994)
Algorithms for Quantum Computation: Discrete Logarithms and Factoring
https://arxiv.org/abs/quant-ph/9508027Grover, L. (1996)
A Fast Quantum Mechanical Algorithm for Database Search
https://arxiv.org/abs/quant-ph/9605043NSA Cybersecurity Directorate
Quantum Computing and Post-Quantum Cryptography
https://www.nsa.gov/what-we-do/cybersecurity/post-quantum-cybersecurity-resources/
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