Quantum computing has moved from a largely theoretical field of physics into an increasingly serious technology and cybersecurity issue. While today’s quantum computers are nowhere near capable of breaking the encryption that protects most of the internet, progress in hardware, error correction and quantum algorithms is accelerating. For cybersecurity leaders, the important question is no longer “Will quantum computing matter?” but “Will our organization be ready when it matters?”
The answer should be yes—and preparation needs to begin now.
Quantum Computing Is Moving Beyond the Laboratory
Traditional computers process information as bits represented by 0s and 1s. Quantum computers use qubits, which can exploit quantum phenomena such as superposition and entanglement to perform certain types of calculations fundamentally differently.
The industry is still working through major engineering challenges, particularly error rates and the difficulty of scaling from physical qubits to reliable logical qubits. Nevertheless, 2026 has brought increasingly ambitious roadmaps.
IBM, for example, says its current Nighthawk platform is designed to demonstrate increasingly sophisticated quantum-classical workloads, while its roadmap targets a large-scale fault-tolerant system, Starling, around 2029. IBM says Starling is intended to operate with 200 logical qubits and execute circuits involving up to 100 million quantum gates.
IBM has also committed more than $10 billion over five years to quantum computing research, manufacturing, acquisitions and ecosystem development—an indication that major technology companies increasingly view quantum computing as a strategic technology rather than an academic experiment.
That does not mean a cryptographically relevant quantum computer will definitely arrive in 2029. Estimates vary considerably. But the uncertainty itself is one reason organizations should prepare.
The Cybersecurity Problem: Shor’s Algorithm
The biggest concern is cryptography.
Much of today’s digital security relies on public-key cryptographic algorithms such as RSA and elliptic-curve cryptography (ECC). They protect everything from websites and VPN connections to digital certificates, software updates, financial transactions and identity systems.
Their security depends on mathematical problems that are extremely difficult for conventional computers.
A sufficiently powerful quantum computer, however, could use Shor’s algorithm to solve some of those problems dramatically faster.
The consequence could be profound.
An attacker with a sufficiently capable quantum computer could potentially derive private keys from public information and compromise systems that currently depend on RSA or ECC. Digital signatures could also be forged, undermining authentication and software integrity.
Importantly, today’s quantum computers cannot do this at practical scale. The threat is a future one—but organizations cannot simply wait until the technology arrives.
“Harvest Now, Decrypt Later” Changes the Timeline
One of the most important cybersecurity implications is the harvest-now, decrypt-later (HNDL) threat.
An attacker does not necessarily need a quantum computer today.
Instead, they can steal encrypted information now and store it. If sufficiently powerful quantum computing becomes available years from now, that attacker could attempt to decrypt the historical data.
This is particularly concerning for information with a long useful life:
- Government and defense information
- Intellectual property
- Healthcare records
- Financial information
- Authentication credentials
- Corporate strategic plans
- Personal information
- Long-lived industrial secrets
For example, an encrypted file stolen in 2026 might still be valuable in 2035. If it can eventually be decrypted, the organization has already lost the confidentiality it assumed it had.
This is why quantum security is not simply a future infrastructure problem. Sensitive data being generated today may already be at risk.
Post-Quantum Cryptography Is Already Here
The good news is that organizations do not need to build quantum computers to defend against them.
The cybersecurity industry is developing post-quantum cryptography (PQC)—cryptographic algorithms designed to resist attacks from both conventional and quantum computers.
NIST finalized three major PQC standards in 2024:
- FIPS 203 / ML-KEM — designed primarily for key establishment and encryption.
- FIPS 204 / ML-DSA — designed for digital signatures.
- FIPS 205 / SLH-DSA — another digital-signature approach based on hash functions and intended to provide cryptographic diversity.
NIST is now encouraging organizations to begin applying these standards rather than waiting for a future “Q-Day.”
This is an important shift. The question is no longer whether quantum-resistant algorithms exist. They do. The challenge is deploying them at enterprise scale.
Crypto-Agility Becomes a Cybersecurity Requirement
Perhaps the most important lesson from the quantum threat is the need for crypto-agility.
Many organizations don’t actually know everywhere cryptography is being used.
Encryption and digital signatures can be embedded in:
- Applications
- Operating systems
- Cloud platforms
- VPNs
- TLS certificates
- APIs
- Databases
- Mobile applications
- IoT devices
- Industrial control systems
- Third-party software
- Hardware and firmware
Replacing cryptography across this ecosystem could take years.
Consequently, organizations should develop a cryptographic inventory or cryptographic bill of materials (CBOM) and identify which systems depend on vulnerable algorithms. IBM’s current quantum roadmap similarly recommends cryptographic inventories, risk assessments, migration of vulnerable cryptography and crypto-agility frameworks.
The goal is to make cryptographic components replaceable without having to redesign entire applications.
Quantum Computing Also Creates New Security Questions
The cybersecurity impact of quantum computing extends beyond breaking RSA and ECC.
As organizations begin using remote quantum computing services, new security questions emerge around protecting quantum workloads, intellectual property and algorithms.
Recent research, for example, has demonstrated that information about a quantum workload can potentially leak through observable characteristics of how circuits are compiled and executed on quantum hardware.
This suggests that the future quantum security conversation will involve more than simply replacing encryption algorithms. It may eventually include quantum workload confidentiality, secure quantum-cloud architectures and protection of proprietary quantum algorithms.
What Should CISOs Do Now?
Organizations do not need to panic—but they should start.
A practical quantum-readiness program should include five steps.
First, inventory cryptography. Identify where RSA, ECC and other potentially quantum-vulnerable algorithms are being used.
Second, classify data by longevity. Information that must remain confidential for 10, 20 or 30 years deserves greater priority than information with a short lifespan.
Third, begin PQC testing. Evaluate ML-KEM, ML-DSA and SLH-DSA in applications, VPNs, PKI, certificates and other critical infrastructure.
Fourth, implement crypto-agility. Build systems so cryptographic algorithms can be replaced without major application redesign.
Finally, engage vendors. Organizations should ask technology providers for their post-quantum roadmaps and require quantum-readiness commitments in procurement and third-party risk assessments.
The Bottom Line
Quantum computing represents one of the most significant potential changes to cybersecurity since the emergence of the internet.
The technology is not yet capable of breaking today’s strongest public-key encryption at practical scale, and nobody can say with certainty when a cryptographically relevant quantum computer will arrive. But technological progress is accelerating, major vendors are investing billions, and the migration to quantum-resistant cryptography itself will take years.
The biggest mistake organizations can make is treating quantum security as a problem that begins when the first powerful quantum computer appears.
By then, it may already be too late.
The organizations that prepare now will have time to inventory their cryptographic infrastructure, protect long-lived data, test post-quantum algorithms and build crypto-agile systems. Those that wait for “Q-Day” may find themselves attempting one of the largest cryptographic migrations in history under extreme time pressure.
Quantum computing may still be years away from transforming cybersecurity. Quantum preparedness is not.