Preparing for the Quantum Future: How Organisations Can Defend Against Harvest Now, Decrypt Later Attacks and Adopt Post Quantum Cryptography

Quantum computing is advancing quickly and organisations must now evaluate how future quantum computers will impact data security, encryption methods and cryptographic systems. The emergence of a cryptographically relevant quantum computer will fundamentally change how organisations protect sensitive data, authenticate users and maintain trust in digital services. Estimates suggest that this quantum future may arrive between 2026 and 2030, which means that planning for quantum resistance and post quantum security must begin today.

What Are Quantum Computers?

Quantum computers operate using qubits and the principles of quantum mechanics. Unlike classical computers that rely on binary states, qubits can exist in multiple states simultaneously. This capability allows quantum computers to solve complex mathematical problems that classical computers would take years to complete. As quantum physics research progresses, it becomes increasingly likely that algorithms such as Shor’s algorithm will accelerate the breaking of cryptographic algorithms designed around discrete logarithms and integer factorisation. Once large scale quantum computers become viable, many existing cryptographic methods will no longer provide adequate protection.

How Quantum Computing Impacts Cryptography

Modern encryption methods rely on conventional cryptographic algorithms such as RSA and elliptic curve cryptography. These public key algorithms are built on mathematical problems that classical computers cannot solve efficiently. Quantum computing changes this assumption. A future quantum computer able to execute quantum attacks would be capable of breaking current encryption algorithms, compromising digital signatures, key exchange mechanisms, cryptographic methods for identity verification and the wider landscape of public key infrastructures that organisations depend on. This shift therefore affects network security, cloud platforms, authentication systems and all trust services built on today’s encryption technologies.

Harvest Now, Decrypt Later Attacks

The quantum threat is already being exploited. Adversaries are capturing encrypted data with long term value, storing it and waiting for quantum resistant cryptographic algorithms to be bypassed in the coming years. This approach is known as Harvest Now, Decrypt Later. Any encrypted data transmitted or stored today remains vulnerable because once a quantum computer is capable of breaking existing cryptographic algorithms, attackers will be able to decrypt this information retrospectively. Organisations operating in government, financial systems, defence, healthcare and critical infrastructure carry the highest exposure due to the long lifespan of their data and the sensitivity of the information they manage.

What Is Post Quantum Cryptography?

Post quantum cryptography refers to cryptographic algorithms designed to remain secure against both classical computers and quantum computers. These post quantum algorithms include lattice based algorithms, code based cryptography, hash based signatures and multivariate approaches. The National Institute of Standards and Technology is currently defining post quantum cryptography standards that will replace existing cryptographic algorithms as they become vulnerable. The Internet Engineering Task Force is also introducing protocols and specifications for post quantum encryption, key establishment, cryptographic systems and certificate handling. Post quantum cryptographic algorithms will introduce new key sizes, new security assumptions, updated hash functions and new requirements for constrained devices and existing hardware.

Why Organisations Need Crypto Agility

Adopting quantum resistant cryptography is not a single change. Organisations must achieve crypto agility, which is the capability to replace existing cryptographic algorithms with new quantum resistant algorithms quickly and safely. Crypto agility requires an understanding of current encryption methods, certificate use, algorithm dependencies, public key infrastructures and the cryptographic algorithms designed into applications across the enterprise. Without crypto agility, organisations risk being unable to retire current encryption algorithms or migrate to post quantum encryption algorithms when required by regulators, standards bodies or security advisories.

The Path Toward a Quantum Safe Future

Preparing for post quantum cryptography means assessing cryptographic assets, updating governance, modernising PKI and identifying where current encryption algorithms are embedded in operational systems. Organisations must address key exchange protocols, digital signatures, cryptographic methods used in applications, key establishment processes and certificate lifecycle management. Hybrid solutions that combine classical algorithms with quantum resistant algorithms provide a transitional approach while standards mature. This is essential for organisations seeking to maintain data integrity, protect high value data and ensure continuity across a quantum era.

How Unsung Supports Quantum Readiness

Unsung is a specialist in PKI, cryptographic systems and digital trust. Our expertise spans discovery, design, implementation and managed services across complex, regulated and high assurance environments. We support organisations with cryptographic readiness assessments, enabling them to identify where existing cryptographic algorithms are used and where quantum resistant encryption will be required. Our consultants design quantum resilient PKI architectures, implement certificate lifecycle automation and support compliance with both current and emerging post quantum cryptography standards. As a vendor neutral consultancy, we work with leading manufacturers to select the right technologies and support crypto agility, cryptographic modernisation and secure transformation across critical services. Our experience includes guiding organisations on key establishment, cryptographic policies, post quantum cryptography PQC adoption, algorithm transitions and the integration of post quantum encryption into operational platforms.

Preparing Now for Post Quantum Cryptography

Quantum computing is not a distant concept but an active challenge requiring preparation today. Organisations that manage sensitive data or operate critical infrastructure must evaluate their cryptographic posture, understand algorithm dependencies and plan the migration to post quantum cryptographic standards. Unsung helps organisations build crypto agile architectures, assess vulnerabilities and prepare for a quantum safe future. To discuss a readiness assessment or to explore how Unsung can support your cryptographic transition, contact us using the form below.

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