QTS-09.9: Hybrid / Composite Cryptography
Mechanisms exist to leverage hybrid/composite algorithms as a transition path to Post-Quantum Cryptography (PQC) solutions that: (1) Support hybrid signatures (e.g., ECDSA + ML-DSA) and hybrid Key Encapsulation Mechanisms (KEMs) (e.g., ECDH + ML-KEM); (2) Ensure certificate formats, Public Key Infrastructure (PKI) and trust anchors can support dual-key or dual-certificate models; and (3) Plan for eventual removal of classical algorithms once PQC confidence is sufficient.
Control Question: Does the organization leverage hybrid/composite algorithms as a transition path to Post-Quantum Cryptography (PQC) solutions that: (1) Support hybrid signatures (e.g., ECDSA + ML-DSA) and hybrid Key Encapsulation Mechanisms (KEMs) (e.g., ECDH + ML-KEM); (2) Ensure certificate formats, Public Key Infrastructure (PKI) and trust anchors can support dual-key or dual-certificate models; and (3) Plan for eventual removal of classical algorithms once PQC confidence is sufficient?
EMEA (1)
| Framework | Mapping Values |
|---|---|
| EMEA Germany C5 2026 | CRY-01.02AC.3 |
APAC (1)
| Framework | Mapping Values |
|---|---|
| APAC Australia ISM June 2026 | ISM-1996 |
Capability Maturity Model
Level 0 — Not Performed
Practices are non-existent, based on the inability to demonstrate an implemented and operational capability. A reasonable person would conclude the control is not being performed.
Level 1 — Performed Informally
Quantum Security (QTS) domain capabilities are ad hoc and inconsistent. Capability criteria associated with this control may include:
Level 2 — Planned & Tracked
SCR-CMM Level 2 criteria definitions are not available for this control: ▪ A reasonable person would conclude a well-defined and standardized process is required. ▪ At this level of maturity, the “requirements-driven” nature of performing the control is focused on a localized and/or regionalized implementation, not uniform and consistent across the organization. ▪ Requirements are narrowly scoped for applicability and are primarily derived from compliance obligations (e.g., laws, regulations and contracts).
Level 3 — Well Defined
Quantum Security (QTS) capabilities are standardized across the entity for applicability to People, Processes, Technologies, Data and/or Facilities (PPTDF) to ensure consistency for Technology Assets, Applications, Services and/or Data (TAASD). Capability criteria associated with this control reasonably expect the following criteria to exist: ▪ Policies and standards associated with QTS domain capabilities are formally documented and centrally-managed by the entity's Governance, Risk & Compliance (GRC) team, or similar function. ▪ Standardized Operating Procedures (SOP) associated with QTS domain capabilities are well-documented and kept current by process owners. ▪ A risk management team, or similar function, is appropriately staffed and supported to implement and maintain QTS domain capabilities. ▪ Technology is leveraged to enhance the efficiency and accuracy of risk management operations (e.g., risk management solution, GRC platform and TPRM tool). ▪ The entity's Governance, Risk & Compliance (GRC) team, or similar function, works with business stakeholders and process owners to appropriately scope and reasonably implement cybersecurity and data protection controls associated with QTS domain capabilities to address Minimum Compliance Requirements (MCR) (e.g., applicable statutory, regulatory and/or contractual requirements) and Discretionary Security Requirements (DSR) (e.g., entity-required controls). ▪ An implemented and operational capability exists to leverage hybrid/composite algorithms as a transition path to Post-Quantum Cryptography (PQC) solutions that: (1) Support hybrid signatures (e.g., ECDSA + ML-DSA) and hybrid Key Encapsulation Mechanisms (KEMs) (e.g., ECDH + ML-KEM); (2) Ensure certificate formats, Public Key Infrastructure (PKI) and trust anchors can support dual-key or dual-certificate models; and (3) Plan for eventual removal of classical algorithms once PQC confidence is sufficient.
Level 4 — Quantitatively Controlled
Utilize SCR-CMM Level 3 criteria definitions: ▪ There are no defined Level 4 criteria, since it is reasonable to assume a quantitatively-controlled process is not necessary to operationalize this control. ▪ While it may be possible to develop “metrics-driven” capabilities for this control, the criteria would be organization-specific to define.
Level 5 — Continuously Improving
Utilize SCR-CMM Level 3 or Level 4 (if available) criteria definitions: ▪ There are no defined Level 5 criteria, since it is reasonable to assume a continuously-improving process is not necessary to operationalize this control. ▪ Level 5 capabilities should be considered “world-class” where the control builds on Level 4 capabilities, but are continuously improving through Artificial Intelligence (AI) and/or Machine Learning (ML) technologies. ▪ While it may be possible to develop responsive capabilities for this control through the use of AI and/or ML technologies, the criteria would be organization-specific to define.
Assessment Objectives
- QTS-09.9_A01 hybrid/composite algorithms are leveraged as a transition path to Post-Quantum Cryptography (PQC) solutions, where applicable.
- QTS-09.9_A02 solutions support hybrid signatures (e.g., ECDSA + ML-DSA) and hybrid Key Encapsulation Mechanisms (KEMs) (e.g., ECDH + ML-KEM).
- QTS-09.9_A03 certificate formats, Public Key Infrastructure (PKI) and trust anchors can support dual-key or dual-certificate models.
- QTS-09.9_A04 plans exist for eventual removal of classical algorithms once PQC confidence is sufficient.
Technology Recommendations
Micro/Small
- Rely on browser/cloud/VPN vendors enabling hybrid PQC key exchange (e.g., X25519MLKEM768 in TLS)
Small
- Monitor TLS library and browser vendor hybrid PQC support
- Plan adoption of hybrid modes when widely available
Medium
- Pilot hybrid cryptography for highest-risk external-facing services
- IETF hybrid draft standards monitoring
- Vendor hybrid mode support assessment
Large
- Hybrid cryptography deployment for critical services
- ECDH + ML-KEM hybrid KEM support
- Hybrid certificate testing and deployment
Enterprise
- Enterprise hybrid cryptography deployment program
- Hybrid KEM (ECDH + ML-KEM) and hybrid signatures (ECDSA + ML-DSA)
- PKI infrastructure supporting dual-key/dual-certificate models
- Plan for classical algorithm sunset post-PQC confidence