You don’t need quantum hardware for post-quantum security

Post-quantum cryptography protects against quantum threats using today’s hardware. Quantum tech like QKD may sound appealing, but it isn’t necessary or sufficient to secure organizations.

You don’t need quantum hardware for post-quantum security

2025-09-19

Luke Valenta

9 min read

This post is also available in 日本語.

Organizations have finite resources available to combat threats, both by the adversaries of today and those in the not-so-distant future that are armed with quantum computers. In this post, we provide guidance on what to prioritize to best prepare for the future, when quantum computers become powerful enough to break the conventional cryptography that underpins the security of modern computing systems.  We describe how post-quantum cryptography (PQC) can be deployed on your existing hardware to protect from threats posed by quantum computing, and explain why quantum key distribution (QKD) and quantum random number generation (QRNG) are neither necessary nor sufficient for security in the quantum age.

Are you quantum ready?

“Quantum” is becoming one of the most heavily used buzzwords in the tech industry. What does it actually mean, and why should you care?

At its core, “quantum” refers to technologies that harness principles of quantum mechanics to perform tasks that are not feasible with classical computers. Quantum computers have exciting potential to unlock advancements in materials science and medicine, but also pose a threat to computer security systems. The term Q-day refers to the day that adversaries possess quantum computers that are large and stable enough to break the conventional public-key cryptography that secures much of today’s data and communications. Recent advances in quantum computing have made it clear that it is no longer a question of if Q-day will arrive, but when.

What does it mean, then, for your organization to be quantum ready? At Cloudflare, our definition is simple: your systems and communications should be secure even after Q-day.

However, this definition often gets muddied by vendors insisting that products built using quantum technology are required in order to secure an organization against quantum adversaries. In this blog post we explain why quantum technologies are neither necessary nor sufficient to protect against attacks by a quantum adversary.

The good news is that there is already a solution: post-quantum cryptography (PQC). PQC protects against attacks by quantum adversaries, but PQC is not a quantum technology — it runs on conventional computers without specialized hardware. You can use PQC today on the computers you already have, without buying expensive new hardware.

Post-quantum cryptography

We’ve written quite a few blog posts on post-quantum cryptography already, so we will keep this section brief.

The public-key cryptography that we’ve used for decades to secure our data and communications is based on math problems (like factoring large numbers) that are believed to be computationally hard to solve on conventional computers. If you can efficiently solve the underlying math problem, you can efficiently break the cryptography and the systems that depend on it. As it turns out, the math problems underlying much of today’s public-key cryptography can be efficiently solved by specialized algorithms, like Shor’s algorithm, on large-scale quantum computers.

The solution? Pick new hard math problems (like finding “short” vectors in algebraic lattices) that are no easier to solve with a quantum computer than with a conventional computer. Then, build new cryptographic systems around them. The US National Institute of Standards and Technologies (NIST) launched an international competition in 2016 to identify and standardize such cryptographic systems, which resulted in several new standards for post-quantum cryptography being published in 2024, and several more under consideration for future standardization.

Post-quantum cryptography (PQC) runs on your existing phones, laptops, and servers. PQC runs at Internet scale and can even be more performant than classical cryptography. Except in rare cases, like when you need additional hardware acceleration in cheap smartcards or to replace legacy systems that lack cryptographic agility, there is no need to purchase new hardware to migrate to PQC.

If you want to know how to protect your organization from security threats posed by quantum computers, you can stop reading now. Post-quantum cryptography is the solution. 

Alternatively, you can read below for our perspective on hardware-based quantum security technologies that are sometimes marketed as security solutions.

Quantum security technologies

Quantum technologies capture the imagination. Quantum computers (possibly linked together in a quantum Internet) promise to deliver breakthroughs in drug discovery and materials science via advanced molecular simulation. Measurement of physical quantum processes can be used to generate entropy with mathematically provable properties.

This is exciting technology and fundamental scientific research. But this technology is not required to secure data and communications against quantum attackers.

In this section, we’ll explain why quantum security technologies do not need to be part of your quantum readiness strategy, and any decision to invest in quantum technology should not be based on a desire to defend data and communications systems against the threat of quantum adversaries. Instead, investments should be based on a desire to improve quantum technologies in their own right, for example to help with applications like chemistry, machine learning, and financial modeling.

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