Quantum computing represents both a technological breakthrough and a security threat that organisations must begin preparing for today. While fault-tolerant quantum computers capable of breaking current encryption standards do not yet exist at scale, the timeline for their arrival is shortening. More critically, adversaries are already collecting encrypted data with the intention of decrypting it once quantum capabilities mature, a strategy known as harvest now, decrypt later.
Current public-key cryptography systems, including RSA and elliptic curve algorithms, derive their security from mathematical problems that classical computers cannot solve efficiently. Quantum computers running Shor’s algorithm will solve these problems in practical timeframes, rendering the encryption that protects internet communications, financial transactions, and government secrets fundamentally insecure.
The harvest-now-decrypt-later threat makes quantum preparation an immediate concern rather than a distant one. Data encrypted today using algorithms vulnerable to quantum attack, including diplomatic communications, medical records, financial data, and intellectual property, may be captured by adversaries who plan to decrypt it in future years. If your data retains sensitivity for a decade or more, the quantum threat applies to you right now.
Post-quantum cryptography standards have been developed and are progressing through standardisation. Organisations should begin familiarising themselves with these algorithms and planning migration strategies. The transition from current to post-quantum cryptographic algorithms will affect every system that uses encryption, which in modern organisations means virtually everything.
Cryptographic inventory represents the essential first step. Organisations cannot migrate what they have not mapped. Cataloguing every system, application, protocol, and certificate that relies on cryptographic algorithms reveals the scope of the migration challenge. Most organisations significantly underestimate their cryptographic footprint until they conduct this inventory.
Expert Commentary
William Fieldhouse | Director of Aardwolf Security Ltd
“Quantum computing poses a genuine long-term threat to current encryption standards, and the harvest-now-decrypt-later approach means the risk is already active. Adversaries are collecting encrypted data today with the expectation of decrypting it once quantum computers mature. Organisations handling data with long-term sensitivity need to start their migration to post-quantum cryptography now.”
Hybrid approaches that combine current and post-quantum algorithms offer a practical transition path. Running both algorithms simultaneously ensures that data remains protected even if one algorithm proves vulnerable, whether to quantum or classical attack. This belt-and-braces approach provides assurance during the transition period when confidence in new algorithms is still building.
Testing post-quantum algorithms for performance and compatibility within your specific environment identifies practical challenges before migration begins at scale. Some post-quantum algorithms use larger key sizes and different performance characteristics that may affect network throughput, storage requirements, and application behaviour. Early testing surfaces these issues while there is time to plan solutions.
Regular security assessments from the best penetration testing company should begin incorporating quantum readiness evaluations. Understanding which of your current cryptographic implementations face the greatest quantum risk, and how quickly you could migrate them, provides leadership with actionable intelligence for strategic planning.
Cloud environments require particular attention because encryption underpins so many cloud services. Azure penetration testing and equivalent assessments for other providers should evaluate which cloud services use quantum-vulnerable encryption, what migration options the provider offers, and whether customer-managed keys provide a pathway to post-quantum algorithms ahead of provider-side migration.
The quantum transition will be one of the largest cryptographic migrations in computing history. Organisations that begin planning, inventorying, and testing now will navigate this transition smoothly. Those that wait until quantum computers arrive will face an emergency migration under pressure, with adversaries potentially already holding years of their captured encrypted data.
