How will quantum computing affect current encryption standards?

Quantum computing will upend the mathematical assumptions underlying much of today’s public-key cryptography, forcing a widespread re-evaluation of standards and practices. Peter Shor at the Massachusetts Institute of Technology demonstrated in 1994 that a sufficiently powerful quantum computer running Shor’s algorithm can factor large integers and compute discrete logarithms in polynomial time, directly threatening RSA and elliptic-curve cryptography that secure internet key exchange and digital signatures. Lov Grover at Bell Laboratories showed that quantum search can accelerate brute-force attacks, effectively halving symmetric key strength unless key sizes are increased.

Quantum threat to public-key cryptography

The immediate technical relevance is that public-key systems used for key establishment and authentication rely on mathematical problems that are efficiently solvable by known quantum algorithms. This means encrypted sessions protected today by RSA or ECC could be exposed retroactively once quantum machines reach the required scale and error rates. Michele Mosca at the University of Waterloo and other researchers have emphasized the “harvest now, decrypt later” risk where adversaries capture encrypted traffic today for future decryption. Symmetric cryptography and hashing are less vulnerable: Grover’s algorithm provides only a square-root speedup, so increasing key lengths and hash sizes can mitigate that class of risk without changing primitives.

Transition to post-quantum standards and consequences

The National Institute of Standards and Technology has led an international response through its Post-Quantum Cryptography standardization process, selecting lattice-based algorithms such as CRYSTALS-Kyber and CRYSTALS-Dilithium for standardization. These algorithms are based on hard problems in lattices that, so far, are believed to resist known quantum attacks. Adoption of these post-quantum primitives will require coordinated updates across software stacks, hardware security modules, certification processes, and supply chains. The practical consequences include engineering challenges for constrained devices, legacy systems that cannot be easily patched, and legal or regulatory issues where signatures and archives must remain verifiable over long terms.

Beyond technical migration, quantum impacts carry human, cultural, and territorial dimensions. Nations and corporations that achieve practical quantum advantage may gain disproportionate capabilities in signals intelligence, intellectual property recovery, and cryptanalysis, concentrating power where advanced research infrastructure and capital are already present. Communities and small businesses with limited resources face higher barriers to upgrading cryptographic infrastructure, potentially widening digital security inequality. Environmental and logistical considerations also matter: building and maintaining quantum hardware depends on specialized facilities, rare materials, and energy-intensive cooling systems, which influence where and how quantum capability develops.

Trust, governance, and timelines intersect: uncertainty about when fault-tolerant quantum machines will arrive complicates planning. Standards bodies, national security agencies, and industry consortia are recommending phased migration strategies, inventorying cryptographic assets, and prioritizing protection of sensitive, long-lived data. Successful transition will depend on transparent technical assessment, public-sector coordination, and funding to assist resource-limited organizations in implementing post-quantum algorithms, ensuring that cryptographic security remains resilient in a quantum era.