Building a CBOM

What a CBOM is and what it should cover

A cryptographic bill of materials (CBOM) is an inventory of cryptographic elements and their relationships within an organization’s technology estate. The cited standards evidence places CBOM work within a broader bill-of-materials model: CycloneDX is described as a full-stack BOM standard supporting software, SaaS, hardware, machine learning, cryptography, manufacturing, and operations bills of materials, as well as vulnerability disclosure reports, vulnerability exploitability exchanges, and attestations. That breadth is useful because cryptography is rarely confined to application source code. It may appear in protocols, libraries, firmware, hardware, infrastructure, certificates, signatures, key-management services, and supplier products.1

Define the initial scope in terms of business services and technology boundaries rather than attempting to collect every possible record at once. Include internally developed and acquired software, open-source components, cloud-hosted products, commercial off-the-shelf products, network protocols, servers, end-user systems, operational technology, industrial control systems, and software or firmware update mechanisms where they are relevant to the organization’s risk. The CISA SBOM evidence states that SBOM scope can apply to software acquired or developed by agencies and its components, including open-source software and artificial intelligence; the quantum-readiness evidence separately emphasizes IT and OT systems, custom-built and COTS technology, and cloud services. These passages support extending discovery beyond conventional application inventories.23

Why build a CBOM

The immediate reason to build a CBOM is visibility. CISA describes an SBOM as an “ingredients list” that illuminates the software supply chain and supports risk-informed decisions. It also states that software volume is too high for manual assessment and that a machine-processable, scalable model is needed. The same reasoning applies to cryptography: an organization cannot reliably prioritize weak, obsolete, exposed, or difficult-to-change cryptographic use if it does not know where that use exists.2

A CBOM also supports forward-looking planning. The joint CISA, NSA, and NIST fact sheet encourages organizations to establish a cryptographic inventory of quantum-vulnerable technology and the criticality of associated data. It identifies inventory as an input to risk assessment and migration prioritization, including systems involved in creating and validating digital signatures, software and firmware updates, network protocols, end-user systems, servers, applications, and associated libraries.3

Finally, a CBOM can make crypto-agility work concrete. NIST defines crypto agility as the capability to replace and adapt algorithms in protocols, applications, software, hardware, firmware, and infrastructures while preserving security and ongoing operations. An inventory helps teams locate transition points, identify dependencies, estimate change impact, and track whether planned replacements have reached the systems that need them. It does not make a system agile by itself; it provides evidence for designing and operating the mechanisms that enable controlled change.5

A practical CBOM-building workflow

Build the CBOM as an operating workflow, not a one-time spreadsheet exercise. The following sequence is a practical implementation pattern grounded in the cited evidence. Organizations may combine or reorder activities according to their architecture, but each activity should produce an auditable result and an accountable owner.24

1. Assign governance and ownership. Establish a project team with security, architecture, application, infrastructure, OT, procurement, privacy or data-governance, and supplier-management participation. Define who produces records, who validates them, who can consume them, and who approves risk treatment.
2. Set boundaries and priorities. Map critical business services to applications, platforms, data stores, networks, devices, suppliers, and cloud services. Start with high-impact systems, industrial control systems, systems with long-term confidentiality or secrecy needs, externally exposed services, and update or signing infrastructure.
3. Discover cryptographic use. Use available discovery methods across source code, binaries, configurations, protocols, certificates, key stores, application libraries, hardware, firmware, appliances, cloud services, and vendor documentation. Capture both direct use and inherited use through dependencies.
4. Normalize and relate records. Use stable identifiers for assets, components, algorithms, protocols, keys or certificates, services, suppliers, and environments. Relate a cryptographic mechanism to the function it performs, the asset that invokes it, the data or authorization it protects, and the upstream or downstream dependency that could constrain change.
5. Enrich with lifecycle and risk context. Record whether an item is planned, active, retired, or otherwise unavailable for normal operation; its owner; environment; exposure; data lifetime; algorithm and key parameters; implementation or provider; and known migration or replacement path.
6. Validate with system owners and suppliers. Reconcile automated findings with architecture and operational knowledge. Ask COTS and cloud providers about their quantum-readiness roadmaps, planned updates or upgrades, configuration changes, and application-update requirements.
7. Publish, protect, and update. Distribute the appropriate view to authorized consumers, preserve provenance and timestamps, accommodate updates, and connect changes in systems, dependencies, certificates, keys, and vendors to CBOM review.
8. Analyze and act. Map records to vulnerabilities, advisories, data criticality, operational constraints, technology roadmaps, and migration work. Track decisions, exceptions, remediation, testing, and residual risk rather than treating inventory completion as the end state.

The workflow should distinguish discovery confidence from risk conclusions. A missing record can mean that cryptography was not found, that the discovery method did not cover the asset, that a supplier withheld information, or that the record is awaiting validation. CISA’s 2025 SBOM evidence discusses known and redacted information and the importance of reducing ambiguity about why information may not be provided. Apply the same discipline to CBOM gaps: record the reason, owner, date, and next investigation step.2

What to record

There is no single evidence passage in this bundle that mandates a universal CBOM field set. A useful design therefore separates identification, cryptographic detail, usage context, lifecycle, ownership, provenance, and action. The objective is to retain enough context to answer operational questions: Where is this cryptography used? What does it protect? What depends on it? How difficult would replacement be? What should happen next?12

NIST SP 800-57 provides a useful reminder that cryptographic context affects risk. Its cited factors include the mechanism’s embodiment and operating environment, personnel turnover, transaction or data-flow volume, the security life of data, algorithm-usage limitations such as invocation limits intended to avoid nonce reuse, the security function, rekeying method, and rekeying or key-derivation process. These are not merely descriptive fields: they can change the meaning and urgency of an otherwise identical algorithm record.4

Key records deserve lifecycle treatment. NIST describes four key-management phases: preoperational, operational, postoperational, and destroyed. It also explains that key-management metadata can include the identity of a person or system associated with a key and the information that person is authorized to access. A CBOM should therefore avoid flattening keys into static labels; it should preserve relevant state, relationships, and authorization context without exposing secret key material.4

Architecture, formats, and operating controls

Use a canonical repository or service that can ingest records from discovery tools, engineering pipelines, certificate and key-management processes, configuration management, asset inventories, supplier questionnaires, and cloud or platform evidence. Store relationships rather than only rows: an application may call a library, use a protocol, obtain a certificate, depend on a cloud service, and protect data whose confidentiality period exceeds the application’s release cycle. The resulting graph or relational model should support search, comparison, history, ownership, and export.43

Choose an interoperable representation appropriate to the organization’s ecosystem. The cited OWASP evidence identifies CycloneDX as ECMA-424 and states that the project provides standards in JSON, XML, and protocol buffers, with support for CBOM as part of its broader BOM model. That makes CycloneDX a relevant standardization option to evaluate; the evidence does not establish that it is mandatory, sufficient for every enterprise, or the only suitable representation.1

Apply access control and data minimization deliberately. A CBOM may reveal sensitive architecture, defensive controls, certificate relationships, supplier dependencies, and operational technology details. Share the least information needed for each use case, protect distribution channels, and separate inventory metadata from secret key material. The CISA evidence describes distribution and delivery as incorporating access controls and emphasizes machine-processable, scalable sharing; it also states that SBOM data should accommodate updates. Those principles support controlled distribution and versioned maintenance for CBOM data.2

Using the CBOM for risk and migration

Prioritize by impact, exposure, data lifetime, and change difficulty rather than by algorithm name alone. The joint quantum-readiness guidance specifically calls for priority attention to high-impact systems, industrial control systems, and systems with long-term confidentiality or secrecy needs. It also says that custom-built older products may require the most effort to make quantum-resistant, while COTS products require engagement with vendors about roadmaps and delivery plans.3

For each priority record, identify the protected data or function, its security life, the cryptographic operation involved, the implementation boundary, dependencies, and a credible treatment. Treatments may include migration, a security upgrade that mitigates continued use, configuration change, replacement, compensating controls, or a documented exception. Do not label an item “post-quantum ready” merely because a provider has announced a roadmap: the guidance says final implementation specifics were incomplete in the context of the cited draft standards, and it encourages proactive planning and testing.3

Use controlled transition practices. NIST SP 800-57 warns that changing algorithms can require significant system modifications, including changes related to key sizes and block sizes, and says retained non-cryptographic security measures should be reviewed. It also calls for preimplementation evaluation, testing before deployment, training for new procedures, and care during implementation and transition. A CBOM can make these requirements traceable by linking each planned cryptographic change to affected systems, tests, owners, release dependencies, and operational approvals.4

Measures, limitations, and next steps

Measure whether the CBOM is useful, not only whether it contains many records. Practical measures include coverage of in-scope assets and services; percentage of records with an accountable owner; percentage with validated algorithm, purpose, environment, and lifecycle data; time from cryptographic change to record update; number of unresolved discovery gaps; supplier response coverage; number of high-impact quantum-vulnerable systems with an approved treatment; and successful completion of migration tests. These are implementation measures proposed from the cited evidence, not prescribed metrics from a cited standard.23

A CBOM has important limitations. Automated discovery may miss cryptography hidden in proprietary hardware, firmware, binaries, dynamically configured services, or supplier-managed platforms. Supplier information may be incomplete or redacted. An inventory can identify use without proving that an implementation is correctly configured, securely operated, approved for a particular purpose, or free of vulnerabilities. Likewise, identifying a quantum-vulnerable algorithm does not by itself determine business priority; data lifetime, system impact, exposure, dependencies, and feasible transition paths are necessary context. [claim-0082

• Name an executive sponsor and a technical CBOM owner.
• Select a bounded pilot around one critical service, one platform group, or one high-value data flow.
• Define the minimum record and relationship model, including provenance, confidence, lifecycle, owner, and update date.
• Run discovery across application, infrastructure, protocol, certificate, firmware, cloud, and supplier sources relevant to the pilot.
• Validate findings with system owners and vendors; document unknowns instead of silently dropping them.
• Prioritize records using impact, data security life, exposure, operational constraints, and migration effort.
• Connect approved actions to architecture review, software delivery, vulnerability management, procurement, and continuity processes.
• Expand coverage in measured increments and review the model as standards, products, and organizational technology change.

Conclusion

Building a CBOM means turning cryptographic discovery into an accountable operating capability. Start with a bounded, prioritized scope; capture cryptographic use together with purpose, asset, data, lifecycle, ownership, provenance, and dependencies; validate gaps; use an interoperable and controlled representation; and connect the results to risk decisions, supplier engagement, crypto agility, testing, and post-quantum migration. The CBOM is valuable when it remains current enough to guide action. It is not a security verdict or a substitute for implementation assessment, key management, testing, or risk acceptance.254