Quantum-based attacks are attacks that use a quantum computer to break or weaken cryptographic systems. They mainly target public-key algorithms such as RSA and elliptic-curve cryptography by exploiting quantum algorithms that can factor large numbers or solve discrete logarithms more efficiently than classical computers.
How quantum-based attacks work
Quantum-based attacks are dangerous because they change the assumptions that protect modern public-key cryptography. A sufficiently capable quantum computer could make some widely used algorithms far easier to break than with classical computing alone.
The key issue is not that every cryptographic system fails at once, but that the trust model for RSA and elliptic-curve cryptography depends on problems that quantum algorithms are designed to solve more efficiently. That makes the attack class strategically important even before large-scale fault-tolerant quantum systems are common.
Why they matter for cryptographic trust
These attacks matter because public-key cryptography often protects authentication, key exchange, code signing, software update trust, and encrypted communications. If those foundations weaken, organisations can face exposure well beyond a single cipher or protocol.
In practice, the risk is less about a one-time break and more about long-lived trust compromise. Data captured now may be decrypted later, signatures may no longer be reliable, and systems that depend on durable public-key assurance may need to transition to post-quantum alternatives.
Where exposure is most likely
Exposure is highest where cryptography is embedded deeply into infrastructure and where secrets, certificates, or signatures are expected to remain trustworthy for years. That includes internet-facing services, long-retention data, archived traffic, and systems with slow upgrade cycles.
Organisations also need to consider dependencies outside their direct control, including vendors, managed services, hardware security modules, PKI implementations, and supply-chain components that may adopt quantum-resistant algorithms at different speeds. The practical question is not only what is deployed today, but what must still remain secure later.
Preparing for post-quantum transition
The most useful response is structured cryptographic agility: know where public-key algorithms are used, understand which assets depend on them, and plan for replacement before pressure forces a rushed migration. NIST SP 800-57 Key Management is relevant because key lifecycle decisions shape how quickly an organisation can retire vulnerable algorithms.
Post-quantum migration is usually a programme, not a patch. Systems often need inventory, testing, interoperability planning, certificate and protocol changes, and verification that backup, archive, and identity-dependent workflows still function after algorithm changes. A gradual transition reduces the chance of breaking critical trust relationships while replacing them.
Risk and Threat Considerations
Quantum-based attacks create a time-shifted risk, because intercepted or stored data may be vulnerable later even if it is protected today. The most consequential threat is to trust mechanisms that were assumed to be durable, especially where records, signatures, or encrypted communications must remain confidential or verifiable for long periods.
Failure mechanism: A quantum-capable adversary can target the mathematical assumptions behind RSA or elliptic-curve cryptography, undermining confidentiality, authentication, and non-repudiation in systems that still depend on those algorithms.
Impact: Sensitive archives can become readable, digital signatures can lose assurance value, and affected organisations may be forced into urgent cryptographic migration while also reviewing whether previously protected data or trust chains were exposed.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-57, NIST CSF 2.0 and CIS Controls v8 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-57 | NIST SP 800-57 Part 1 — Key Management | Quantum attacks directly change key lifecycle and algorithm retirement planning. |
| Recommendation — Plan cryptographic migration and retire vulnerable key algorithms before quantum capability matures. | ||
| NIST CSF 2.0 | PR.DS-10 — Cryptography is used to protect confidentiality and integrity | Quantum attacks threaten the cryptographic protections this outcome depends on. |
| PR.PS-02 — The integrity of software, firmware, and information is protected | Quantum attacks can undermine signature-based trust used to validate software and firmware integrity. | |
| Recommendation — Identify where cryptography protects data and replace vulnerable primitives with quantum-resistant options. Preserve update and code-signing trust by migrating integrity controls to post-quantum-capable schemes. | ||
| ISO/IEC 27001:2022 | A.8.24 — Use of cryptography | Quantum attacks materially affect cryptographic selection, use, and transition decisions. |
| Recommendation — Review cryptographic use and transition plans to maintain protection against future cryptanalytic advances. | ||
| CIS Controls v8 | CIS-3 — Data Protection | Quantum attacks threaten confidentiality of protected data over long retention periods. |
| Recommendation — Classify long-lived sensitive data and accelerate encryption transitions for high-value records. | ||
Practitioner Guidance
What to watch for: Treat algorithm inventory as a security requirement, not a documentation exercise. The systems that matter most are often the ones with the longest replacement cycles, the broadest trust blast radius, or the highest need for future confidentiality.
Practitioner note: Migration planning should distinguish between immediate operational risk and future cryptographic risk. A system can appear healthy today and still be strategically exposed if its trust model depends on algorithms that are expected to age poorly against quantum adversaries.
Related resources from NHI Mgmt Group
- Why are identity-based attacks growing faster than traditional network attacks?
- Why are identity-driven attacks harder to detect than malware-based attacks?
- How should security teams protect sessions from infostealer-based attacks?
- How can organisations reduce the risk of token-based attacks in SaaS?