Quick answer: Yes, quantum computing is a genuine threat to cybersecurity, but not an immediate one. A large enough fault-tolerant quantum computer running Shor’s algorithm would break RSA and elliptic-curve encryption entirely, and resource estimates for doing so have fallen sharply, from roughly 20 million qubits in 2019 to under 1 million in 2025, even without a hardware breakthrough. It matters today because adversaries are already harvesting encrypted data to decrypt once such a computer exists. The recommended action is to migrate to NIST’s finalized post-quantum standards (ML-KEM, ML-DSA, SLH-DSA) now, rather than wait for a quantum computer capable of breaking today’s encryption to actually arrive.
Key Takeaways
- Shor’s algorithm allows a sufficiently powerful quantum computer to factor the large numbers underlying RSA encryption, something classical computers cannot do in a practical timeframe.
- Resource estimates for breaking RSA-2048 have fallen from roughly 20 million qubits (2019) to under 1 million (2025), a twentyfold reduction driven by algorithmic improvements rather than new hardware.
- NIST finalized its first three post-quantum standards, ML-KEM (FIPS 203), ML-DSA (FIPS 204), and SLH-DSA (FIPS 205), on August 13, 2024, giving organizations production-ready algorithms to migrate to now.
- Harvest-now-decrypt-later attacks mean long-lived sensitive data, financial records, health data, national security information, is at risk today even though no quantum computer can decrypt it yet.
- A June 2026 executive order requires U.S. federal agencies to complete post-quantum key establishment by December 31, 2030, and digital signatures by December 31, 2031.
Quantum Computing and Cybersecurity
Quantum computers analyze enormous data sets and execute complex computations significantly faster than traditional computers. Google constructed a quantum computer in 2019 that could calculate in 3 minutes and 20 seconds. Still, regular supercomputers would have taken 10,000 years to solve the identical calculation, proving quantum edge or quantum supremacy.
While quantum computing is still in its early stages, upheavals in various areas, including cybersecurity, may occur much sooner than you think. The impact of quantum computing on cybersecurity is tremendous and game-changing.
Quantum computing shows significant promise in various fields, including weather forecasting, artificial intelligence, medical research, etc. However, it poses a substantial threat to cybersecurity, necessitating a shift in how we secure our data.
While quantum computers cannot currently break most of our present types of encryptions, we must immediately keep ahead of the risk and develop quantum-proof solutions. It will be too late if we wait till those powerful quantum computers begin breaking our encryption.
An additional reason to act now
Regardless of when commercially available quantum computers will emerge, the potential of malicious actors harvesting data is another reason to quantum-proof data now. They are already grabbing data and storing it until they can obtain a quantum computer to decipher it.
The data will have already been compromised at that point. The only way to maintain information security, particularly information that must be kept indefinitely, is to protect it today via quantum-safe key transmission.
Quantum Threat to Cybersecurity
Quantum computers will be capable of solving issues that traditional computers are incapable of solving. This involves deciphering the algorithms underlying the encryption keys that safeguard our data and the Internet’s infrastructure.
The encryption used nowadays is largely built on mathematical calculations that would take far too long to decipher on today’s machines. Scientists have been working on constructing quantum computers that can factor progressively bigger numbers since then. Consider two large integers and multiply them together to simplify this. It’s simple to calculate the product, but it’s considerably more difficult to start with a huge number and divide it into its two prime numbers. However, a quantum computer can readily factor those numbers and break the code.
Peter Shor created a quantum method (aptly titled Shor’s algorithm) that can factor in big numbers far faster than a traditional computer.
Today’s RSA encryption is extensively used for transferring critical data over the Internet and is based on 2048-bit numbers. Early resource estimates for breaking that encryption were astronomical: a 2012 analysis put the figure near a billion noisy qubits, and Google researchers Craig Gidney and Martin Ekerå brought that down to roughly 20 million physical qubits in 2019. In May 2025, Gidney published a further refinement showing that fewer than one million noisy qubits could factor a 2048-bit RSA key in under a week, a twentyfold reduction from the 2019 estimate driven by better error-correction techniques rather than new hardware. Even the largest quantum processors built to date, which run into the thousands of physical qubits, remain far short of what large-scale factoring would require, and fault-tolerant systems with enough stable logical qubits to pose a real threat are not expected before the early 2030s at the earliest.
As the speed of quantum research continues to accelerate, the resource estimates for breaking RSA keep shrinking even without new hardware breakthroughs, and that trend is itself a reason not to treat the timeline as comfortably distant.
That downward trend in resource requirements is worth watching closely, since it means the “safe” timeline keeps compressing even before any single breakthrough in physical hardware arrives. Continued algorithmic refinements, rather than a single dramatic leap, have been what actually moved the goalposts so far.
It’s worth mentioning that perishable sensitive data isn’t the major concern when it comes to the quantum encryption issue. The more serious concern is the susceptibility of information that must remain secret indefinitely, such as banking data, privacy data, national security-level data, etc. Those are the secrets that need to be protected by quantum-proof encryption right now.
NIST’s Post-Quantum Standards Are Now Final
The response to this threat is no longer theoretical. On August 13, 2024, NIST finalized its first three post-quantum cryptography standards: ML-KEM (FIPS 203) for key exchange, ML-DSA (FIPS 204) for digital signatures, and SLH-DSA (FIPS 205) as a conservative hash-based signature backup. A fourth signature algorithm, FN-DSA (FIPS 206), remains in draft, and NIST selected a fifth algorithm, HQC, in March 2025 as a backup key-encapsulation mechanism. These are production-ready algorithms that organizations can begin implementing today, not distant research proposals.
Regulatory deadlines are also now binding rather than aspirational. NIST IR 8547 (draft) proposes deprecating 112-bit-strength algorithms like RSA-2048 after 2030 and disallowing all quantum-vulnerable RSA and ECC deployments after 2035. A June 2026 executive order accelerated the U.S. federal timeline further, requiring agencies to complete post-quantum key establishment by December 31, 2030, and digital signatures by December 31, 2031, for high-value and high-impact systems.
Adapting Cybersecurity to Respond to the Threat
Researchers have been working hard to produce “quantum-safe” encryption in recent years. There are many unanswered problems in quantum computing, and scientists are working hard to find answers.
However, one thing is certain about the influence of quantum computing on cybersecurity: it will represent a danger to cybersecurity and current types of encryptions. To mitigate that threat, we must change how we secure our data and begin doing it now.
We must handle the quantum threat the same way we approach other security vulnerabilities: by adopting a defense-in-depth strategy that includes many layers of quantum-safe protection. Security-conscious enterprises recognize the need for crypto agility.
They are looking for crypto-diverse solutions, such as those provided by Encryption Consulting LLC, quantum-safe their encryption now and quantum-ready for tomorrow’s challenges.
Conclusion
Quantum computing is a real threat to cybersecurity, but it is not an urgent one in the sense of an imminent break of today’s encryption. The urgency comes from a different direction: resource estimates for breaking RSA keep falling, harvest-now-decrypt-later attacks put long-lived sensitive data at risk today, and NIST’s finalized post-quantum standards mean there is no longer a technical reason to wait.
Organizations that treat this as a future problem are making a bet that the timeline will stay comfortably distant. The trend so far suggests otherwise. The practical response is to start migrating now, using NIST-approved algorithms like ML-KEM and ML-DSA, and to build the crypto-agility needed to adapt as both the threat and the standards continue to evolve.
Frequently Asked Questions
Is quantum computing a threat to cybersecurity right now?
Not immediately. No quantum computer built today can break current encryption standards like RSA or ECC. The threat is that a future, sufficiently powerful quantum computer could, and adversaries are already collecting encrypted data now to decrypt once that capability exists.
How many qubits would it take to break RSA-2048?
Estimates have fallen sharply over time. Google researchers estimated roughly 20 million physical qubits in 2019; a May 2025 refinement lowered that to under 1 million noisy qubits, capable of factoring a 2048-bit RSA key in under a week. These reductions have come from better error-correction and algorithmic techniques rather than new hardware.
What is “harvest now, decrypt later,” and why does it matter today?
It is a strategy where adversaries intercept and store encrypted data today, intending to decrypt it once a capable quantum computer exists. This makes long-lived sensitive data, such as health records, financial data, and national security information, vulnerable right now, even though no quantum computer can currently break the encryption protecting it.
Which encryption algorithms should organizations migrate to?
NIST finalized ML-KEM (FIPS 203) for key exchange and ML-DSA (FIPS 204) for digital signatures on August 13, 2024, with SLH-DSA (FIPS 205) available as a conservative hash-based signature backup. These are production-ready standards, not draft proposals, and organizations can begin implementing them today.
What is crypto-agility, and why does it matter for the quantum threat?
Crypto-agility is the ability to switch cryptographic algorithms without a major system redesign. It matters because quantum computing resource estimates keep shrinking and standards continue to evolve, so organizations need infrastructure that can adapt rather than being locked into a single algorithm.
