Nearly everything we do online, from banking to messaging to logging into work systems, relies on encryption that today’s computers can’t break. But a new kind of computer could change that. Large, powerful quantum computers are expected to crack some of the world’s most widely used encryption methods.
That future may still be years away, but security teams aren’t waiting. Governments and organizations are already moving to post-quantum cryptography, a new generation of encryption designed to resist quantum-computer attacks. This guide explains what post-quantum cryptography is, why quantum computing threatens today’s encryption, what the new NIST standards are, and how security teams are preparing now.
Encryption scrambles data so only someone with the right key can read it. Most systems use two types:
If you’d like a deeper introduction, start with our guide: What Is Encryption? How It Protects Your Data.
Traditional computers process information as bits, which are either 0 or 1. Quantum computers use qubits, which can represent combinations of 0 and 1 at the same time through quantum properties like superposition and entanglement.
For most everyday tasks, quantum computers won’t replace regular computers. But for certain kinds of math problems, they could be dramatically faster. Unfortunately, some of those problems are exactly what today’s public-key encryption relies on.
RSA and ECC are secure because certain math problems, like factoring very large numbers, would take classical computers an impractically long time to solve.
In 1994, mathematician Peter Shor developed a quantum algorithm, now known as Shor’s algorithm, that could solve these problems efficiently on a sufficiently powerful quantum computer. If that kind of machine is built, it could break RSA and ECC, which protect:
Symmetric encryption is in much better shape. Quantum attacks would weaken it but not break it, and longer keys, such as AES-256, are considered sufficient to remain secure.
The hypothetical moment when a quantum computer can break today’s public-key encryption is sometimes called “Q-Day.” No one knows exactly when it will arrive, and today’s quantum computers aren’t powerful enough. But because migrating to new encryption takes years, security experts agree the time to prepare is now.
One of the biggest reasons for urgency is a strategy known as harvest now, decrypt later.
Attackers, including well-funded nation-states, can intercept and store encrypted data today, even though they can’t read it yet. Once powerful quantum computers exist, they could decrypt that stolen data.
That’s a serious problem for information that needs to stay secret for many years, such as:
If data must stay confidential for 10 or 20 years, it may already be at risk if it’s protected with quantum-vulnerable encryption today.
Post-quantum cryptography (PQC) refers to new encryption algorithms designed to resist attacks from both classical and quantum computers. Despite the name, PQC doesn’t require quantum computers. It runs on the same computers, servers, and devices we use today.
PQC algorithms rely on different math problems, such as lattices and hash functions, that researchers believe quantum computers can’t solve efficiently.
PQC is different from quantum cryptography (like quantum key distribution), which uses quantum physics and specialized hardware to share keys. PQC is software-based, making it much easier to deploy at scale.
After a multi-year global competition, the National Institute of Standards and Technology (NIST) published its first three finalized post-quantum cryptography standards on August 13, 2024:
| Standard | Algorithm | Based On | Used For |
|---|---|---|---|
| FIPS 203 | ML-KEM | CRYSTALS-Kyber | General encryption and key exchange |
| FIPS 204 | ML-DSA | CRYSTALS-Dilithium | Digital signatures |
| FIPS 205 | SLH-DSA | SPHINCS+ | Digital signatures (backup method) |
NIST is also developing a standard for FN-DSA, based on the FALCON algorithm, and in March 2025 selected HQC as an additional key-encapsulation algorithm to serve as a backup to ML-KEM. (Ampcus Cyber)
In a draft report known as NIST IR 8547, NIST proposed a transition timeline for today’s quantum-vulnerable public key algorithms like RSA and ECC:
While the report was still a draft, federal agencies and many organizations are already using these dates for planning. (Encryption Consulting)
If Q-Day could still be years away, why start now? There are several reasons:
The first step is finding out where encryption is used across the organization: applications, certificates, VPNs, databases, devices, and third-party services. Many organizations don’t have a complete picture today.
Teams identify which systems protect the most sensitive or long-lived data and which are most exposed, then plan to upgrade those first.
Crypto-agility is the ability to swap out encryption algorithms without rebuilding entire systems. It makes this migration, and future ones, much easier.
Many organizations are testing hybrid methods that combine traditional and post-quantum algorithms, so connections stay secure even if one method turns out to have weaknesses. Major browsers and cloud providers have already begun rolling out post-quantum key exchange for secure web connections.
Security teams are asking vendors about their PQC roadmaps and including quantum readiness in procurement and contracts.
Good key and certificate management makes migration smoother. It also connects closely to identity and access management. Learn about IAM careers.
PQC planning fits within broader risk management and compliance programs, such as the NIST Cybersecurity Framework and other cybersecurity compliance frameworks.
The move to post-quantum cryptography will be one of the largest security upgrades in history, and skilled professionals will be needed to plan and carry it out. Roles involved include:
For a broader look at the field, explore the top cybersecurity careers in the US.
You don’t need a physics degree to work on post-quantum readiness. Most of the work relies on strong security fundamentals: cryptography, public key infrastructure (PKI), secure protocols, risk assessment, and system architecture.
CIAT’s Unlimited Certification Exam Retake Policy covers all CompTIA certifications, including Security+. The policy excludes CISSP and EC-Council CEH.
Quantum computers may not be able to break today’s encryption yet, but the clock is already running. Harvest-now, decrypt-later attacks, new NIST standards, and approaching migration deadlines mean organizations need to start inventorying their cryptography, building crypto-agility, and planning their move to quantum-safe encryption today. It’s one of the biggest security transitions in history, and it will need skilled professionals to make it happen.
Every post-quantum project requires a solid understanding of cryptography, PKI, and secure architecture. CIAT’s cybersecurity programs cover cryptography and secure communication protocols, along with network security, cloud security, and risk management. The 5-day CompTIA Security+ Bootcamp is a fast way to earn the certification that validates those fundamentals, backed by CIAT’s unlimited retake policy for CompTIA exams.
Ready to help secure the next era of encryption?
Post-quantum cryptography is a new generation of encryption designed to stay secure even against powerful future quantum computers. It runs on today’s regular computers and devices.
No. Today’s quantum computers aren’t powerful enough to break modern encryption. The concern is that future, much larger quantum computers could break widely used public-key methods like RSA and ECC.
Q-Day is the term for the future point when a quantum computer becomes powerful enough to break today’s public key encryption. No one knows exactly when that will happen.
It describes attackers stealing and storing encrypted data today so they can decrypt it once powerful quantum computers are available. It’s a major reason organizations are preparing now.
Quantum computers would weaken symmetric encryption like AES, but not break it. Using longer keys, such as AES-256, is considered sufficient to stay secure.
In August 2024, NIST published FIPS 203 (ML-KEM) for encryption and key exchange, and FIPS 204 (ML-DSA) and FIPS 205 (SLH-DSA) for digital signatures. Additional standards are in development.
No. Post-quantum cryptography uses new math-based algorithms that run on regular computers. Quantum cryptography, such as quantum key distribution, uses quantum physics and specialized hardware.
NIST’s proposed timeline would deprecate quantum-vulnerable algorithms like RSA and ECC after 2030 and disallow them after 2035. Many organizations are starting with a cryptographic inventory now because migration takes years.
Crypto-agility is the ability to replace encryption algorithms quickly without redesigning entire systems. It helps organizations adapt to new standards and threats.
Strong cybersecurity fundamentals, including cryptography basics, PKI, secure protocols, risk management, and security architecture. Certifications like CompTIA Security+ and CISSP cover many of these topics.
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