An organisation considering quantum key distribution has already moved past "should we care about quantum security?" They are asking: "Is QKD the right solution for our specific requirements, and does our infrastructure actually support it?" QKD is not the right answer for every organisation or every use case. it requires specific physical infrastructure, operational capability, and budget commitments that PQC-only migration does not. The qualifier helps organisations make that assessment before committing to QKD procurement. Assess your QKD readiness
What the QKD Network Readiness Qualifier Does
The tool maps your infrastructure profile against QKD's technical requirements and identifies whether deployment is feasible, conditional, or not currently viable for your environment.
Inputs:
- Network topology: point-to-point fibre, metro area network, wide area network, or satellite
- Fibre availability and distance: QKD operates over dedicated optical channels. typically 50 to 150 km over standard dark fibre for commercial BB84-type deployments. Emerging protocols extend this range significantly: Twin-Field QKD has demonstrated approximately 830 km in laboratory conditions. Trusted-node architectures allow longer distances by chaining QKD links through intermediate nodes, at the cost of trust assumptions at each node. Satellite QKD enables intercontinental distances. The commercially deployable figure for your programme depends on infrastructure and implementation type. confirm the current commercial envelope with your vendor during a site survey.
- Security requirement level: what threat model justifies QKD over PQC software migration?
- Budget range: QKD hardware costs are substantially higher than PQC software migration; this input affects the practical feasibility assessment
- Internal operational capability: can your organisation operate dedicated QKD hardware?
- Programme security requirement: as of 2026, no major regulatory framework mandates QKD as a compliance requirement. National security community interest exists. some government security programmes are exploring QKD for their highest-classification communications links. but organisations with specific national security programme requirements should consult their programme security officer about whether QKD is specified in their programme's security architecture
Output: a feasibility classification. viable, conditional, not currently viable, or hybrid feasible. with the primary feasibility factors identified.
The qualifier also addresses the QKD versus PQC decision directly, which is the question most organisations considering QKD actually need to answer.
For background on QKD technology, see QKD explained.
When QKD Is the Right Choice. and When It Is Not
This is the content gap across the web on this topic. Most published guidance either advocates for QKD or dismisses it. The practical answer depends on specific infrastructure and requirements.
When QKD makes sense
Point-to-point links with specific high-security requirements where the parties have dedicated optical infrastructure: government or defence communications, inter-data-centre links for highly classified data, financial clearing infrastructure with high-value static routes.
Environments where the security requirement is information-theoretic rather than computational. QKD makes key distribution unconditionally secure. the security of the key exchange is guaranteed by the laws of quantum mechanics, not by the computational difficulty of a mathematical problem. This is a qualitatively different security guarantee from PQC's computational security. The encryption layer on top of those keys still depends on the encryption algorithm (typically AES-256, which is considered post-quantum secure), so a full QKD deployment provides information-theoretic security on the key distribution layer. The entire communications channel is not unconditionally secure. that framing is imprecise and QKD vendors sometimes overstate it.
Organisations with existing dark fibre between their locations and the operational capability to manage dedicated QKD hardware. QKD requires a dedicated optical channel between communicating parties. It cannot be deployed over standard IP networking infrastructure or the internet. This is a fundamental constraint, not an implementation detail.
When PQC software migration is the better answer
Internet-connected systems, public-facing infrastructure, and cloud workloads: QKD cannot operate over IP networks, so these environments are outside QKD's scope entirely. PQC is a software and protocol update that works across existing network infrastructure.
Large-scale migrations across many systems: PQC is a software and library update replicated across many systems. QKD requires dedicated hardware for each link. the operational model does not scale horizontally the way PQC migration does.
Organisations without dedicated optical fibre between locations: no fibre, no QKD. PQC has no such constraint.
Budget-constrained programmes: QKD hardware, installation, and ongoing operation costs are substantially higher than PQC software migration. For most organisations the cost-benefit analysis strongly favours PQC migration, with QKD reserved for the specific links where information-theoretic key security is genuinely required.
QKD is over-specified for most use cases and under-specified for a small number of critical ones. Most organisations that reach the QKD evaluation stage would be better served completing their PQC migration programme first and then identifying the specific links. typically a handful. that genuinely justify the hardware investment. Deploying QKD before completing PQC migration is the wrong sequencing.
The hybrid position
Some high-security environments will deploy both: QKD for their most sensitive point-to-point links and PQC migration across everything else. The qualifier identifies whether your environment is a candidate for this hybrid position.
Our tools are designed as directional tools only. Advice and standards are changing rapidly and although we update tools as new information is periodically released they are not designed as a replacement for expert advice. If your organisation results show high-priority exposure the next step is to contact our team or speak to a qualified expert member.
How to Use the QKD Network Readiness Qualifier
Step 1. Open the qualifier. No registration required.
Step 2. Select your network topology type. Point-to-point fibre is the most favourable topology for QKD deployment. Metro area networks and satellite topologies require different technical approaches. Wide area networks spanning multiple organisations or jurisdictions introduce trusted-node complexity.
Step 3. Identify the distance between the locations you want to protect. The distance input maps directly to the QKD range constraint. If your locations are within the commercial deployment range for your topology type, QKD is technically feasible from a distance perspective. If they are beyond standard fibre range, a trusted-node architecture or satellite QKD is required. both carry higher complexity and cost.
Step 4. Rate your security requirement level. The question is: does your use case require the qualitatively different security guarantee of information-theoretic key distribution, or is the computational security of PQC sufficient? Government classification requirements, specific programme security architecture specifications, and high-value financial infrastructure are the typical drivers for QKD's security requirement.
Step 5. Indicate your budget range. QKD hardware costs typically run from tens of thousands to hundreds of thousands of pounds or dollars per link, depending on hardware generation and installation requirements. If QKD is not within your budget range, the qualifier will return "conditional" or "not currently viable" on the practical feasibility dimension.
Step 6. Rate your internal operational capability for QKD hardware. This includes managing dedicated dark fibre, operating QKD terminal equipment, and maintaining the classical authentication channels that QKD deployments require alongside the quantum channel.
Step 7. Identify any regulatory requirement specifically specifying QKD. If your programme security architecture or classification guidance specifies QKD, that overrides the standard feasibility assessment. If no such requirement exists, the qualifier evaluates feasibility on technical and economic grounds.
Step 8. Review the feasibility classification and primary feasibility factors.
How to Interpret Your QKD Readiness Results
Viable: your infrastructure, requirements, and budget profile support QKD deployment. The recommended next step is engaging specialist QKD vendors for a site survey and detailed deployment proposal. The qualifier provides the framework assessment; the site survey provides the implementation specifics.
Conditional: QKD is viable if specific conditions are met. The qualifier identifies which conditions need to resolve. for example, if the primary constraint is dark fibre availability to a target site, the condition is an infrastructure investment, not a fundamental barrier. Conditions that are time-bound (budget cycle, infrastructure programme) versus fundamental (internet-connected systems where QKD cannot operate) point to different planning actions.
Not currently viable: QKD is not the right solution for your current infrastructure or requirement profile. The qualifier will indicate whether this is a current constraint or a fundamental one. For most organisations receiving this result, PQC migration is the appropriate path forward.
Hybrid feasible: QKD for specific high-security links is viable alongside a broader PQC migration programme. The qualifier identifies which links are candidates. This is typically the most common outcome for organisations with genuinely high-security requirements. they deploy QKD narrowly on their most sensitive links and complete PQC migration across the rest of their estate.
Discuss your results with a QSECDEF expert member. A directional assessment is the starting point, not the programme. If your results show high-priority exposure, the next step is a discussion about a structured migration programme with defined milestones. Request a consultation with our team or find a qualified expert member.
