Liaison statement
LS on work progress on Quantum Key Distribution (QKD) network in SG13 (as of July 2022)

ITU-T SG13 is pleased to inform you about our progress on Quantum Key
Distribution (QKD) topics. By now it published 10 Recommendations and 1
Supplement on QKDN as follows:

- Recommendation ITU-T Y.3800 “Overview on networks supporting quantum key
distribution”; - Recommendation ITU-T Y.3801 “Functional requirements for
quantum key distribution networks”; - Recommendation ITU-T Y.3802 “Quantum key
distribution networks – Functional architecture”; - Recommendation ITU-T Y.3803
“Quantum key distribution networks – Key management”; - Recommendation ITU-T
Y.3804 “Quantum key distribution networks - Control and management”; -
Recommendation ITU-T Y.3805 “Quantum Key Distribution Networks - Software
Defined Networking Control”; - Recommendation ITU-T Y.3806 “Quantum key
distribution networks - Requirements for quality of service assurance”; -
Recommendation ITU-T Y.3807 “Quantum Key Distribution networks - QoS
parameters”; - Recommendation ITU-T Y.3808 “Framework for integration of
quantum key distribution network and secure storage network”; - Recommendation
ITU-T Y.3809 “A role-based model in quantum key distribution networks
deployment”; - Supplement ITU-T Y.Sup70 “Quantum Key Distribution Networks -
Applications of Machine Learning”

Since our last liaison statement Q16/13 has made progress of the following work
items.

1.The items approved after the December 2021 SG13 meeting

The Recommendations ITU-T Y.3807, Y.3808, Y.3809 were approved.

Recommendation ITU-T Y.3807 (ex Y.QKDN_QoS_pa) “Quantum Key Distribution
networks - QoS parameters”

This Recommendation is to specify Quality of Service (QoS) parameters on the
Quantum Key Distribution Network for the purpose of network operation and
maintenance as follows:

- Descriptions of QoS and Network Performance (NP) on QKDN
- Classification of performance concerns for which parameters may be needed
- QoS parameters of QKDN - Network performance supporting factor.

Recommendation ITU-T Y.3808 (ex Y.QKDN_frint) “Framework for integration of
quantum key distribution network and secure storage network”

This Recommendation describes framework for integrating quantum key
distribution network (QKDN) and secure storage network (SSN). In particular,
the scope of this Recommendation includes: - overview of SSN; - functional
requirements for SSN; - functional architecture model of SSN; - reference
points; - operational procedures.

Recommendation ITU-T Y.3809 (ex Y.QKDN_BM) “A role-based model in quantum key
distribution networks deployment”

This Recommendation describes roles, a role-based model, and service scenarios
in Quantum Key Distribution Network (QKDN) from different deployment and
operation perspectives with existing user networks for supporting security
applications services. This draft Recommendation can be used as a guideline for
applying QKDN from role point of views as well as for deployment and operation
of QKDN from telecom operators’ point of views.

2. The item consented after the December 2021 SG13 meeting

The following draft Recommendation was consented:
Draft Recommendation ITU-T Y.3810 (formerly Y.QKDN-iwfr) “Quantum key
distribution network interworking - framework” in TD37/PLEN For quantum key
distribution networks (QKDN), Recommendation ITU-T Y.QKDN_iwfr specifies
framework of QKDN interworking (QKDNi). This Recommendation describes the
overview of interworking QKDNs, the reference models, and the functional models
of Gateway Functions (GWFs) and Inter Working Functions (IWFs). The
configurations for QKDNi are specified.  Appendix I includes QKDNi with
different key relay schemes

3. Revised on-going work items

Draft Recommendation ITU-T Y.QKDN-iwrq “Quantum key distribution networks
interworking – functional requirements” in TD37-WP3 For quantum key
distribution networks (QKDN), Recommendation ITU-T Y.QKDN_iwrq specifies
functional requirements for QKDNi. This Recommendation describes the general
requirements, the functional requirements for QKDNi with GWNs and the
functional requirements for QKDNi with IWNs. Appendix I includes functional
elements of QKDNi with GWFs and IWFs.

Draft Recommendation ITU-T Y.QKDN-ml-fra “Quantum key distribution networks -
functional requirements and architecture to enable machine learning” in TD38-WP3

QKDN is expected to be able to maintain stable operations and meet the
requirements of various cryptographic applications efficiently. Due to the
advantages of machine learning (ML) related to autonomous learning, ML can help
to overcome the challenges of QKDN in terms of quantum layer performances, key
management layer performances and QKDN control and management efficiency. Based
on the functional requirements and architecture of QKDN in [ITU-T Y.3801] and
[ITU-T Y.3802], this recommendation is to specify a framework for ML-enabled
QKDN (QKDNml), including the role of ML in QKDN, the functional requirements,
architecture and operational procedures of QKDNml.

Draft Recommendation ITU-T Y.QKDN-rsfr “Framework of quantum key distribution
network resilience” in TD39-WP3

For quantum key distribution network (QKDN), Y.QKDN-rsfr specifes framework of
QKDN resilience. This recommendation describes the overview of QKDN resilience,
scenarios and requirements of QKDN protection and recovery. It also includes
different use cases of QKDN resilience for the appendix.

Draft Supplement ITU-T Y.supp.QKDN-roadmap “Standardization roadmap on Quantum
Key Distribution Networks” in TD22-WP3 Supplement Y.supp.QKDN-roadmap to ITU-T
Y-series Recommendations provides the standardization roadmap on quantum key
distribution networks. It describes the landscape with related technical areas
of trust technologies from an ITU-T perspective and list up related standards
and publications developed in standards development organizations (SDOs).

Draft Technical Report ITU-T TR.QEFN: "ITU-T's Views for Quantum-Enabled Future
Networks" in TD21-WP3

The scope of this Technical Report is to describing ITU-T’s Views for
Quantum-Enabled Future Networks for the future networks study to act as a
document to help SG13 to study the future network evolution towards Quantum era.

4. New work items agreed at the July 2022 SG13 meeting

Draft Recommendation ITU-T Y.QKDN-iwac “Quantum key distribution networks
interworking – architecture” in TD44-WP3 This Recommendation specifies
functional architecture for QKDNi. In particular, the scope of this
Recommendation includes the following aspects for QKDNi:

- Functional architecture model for QKDNi;
- Functional elements for QKDNi;
- Basic operational procedures for QKDNi.

Draft Recommendation ITU-T Y.QKDNi_SDNC "Quantum Key Distribution Network
Interworking – Software Defined Networking Control" in TD46-WP3

This new work item specifies the Software Defined Network Control for the
interworking scenarios between QKDN providers. In particular, the
recommendation covers:

- Overview of the role of SDN control for the interworking between QKDN
providers - Functional requirements of SDN control for QKDNi - Functional
entities of SDN control for QKDNi - Interfaces of SDN control for QKDNi -
Overall operational procedures of SDN control for QKDNi - Security
considerations

Draft Recommendation ITU-T Y.QKDNf -fr" Framework of Quantum Key Distribution
Network Federation" in TD47-WP3 This draft new Recommendation specifies the
framework of Quantum Key Distribution Network federation. In particular, the
Recommendation covers:

- Overview and scenarios of QKDN federation (QKDNf)
- Reference architecture for enabling QKDNf
- Functional requirements for QKDNf
- Functional entities for QKDNf
- Reference points for QKDNf
- Overall operational procedures for QKDNf
- Security considerations

5. Conclusion

SG13 will study the network aspects of QKD. Q16/13 looks forward to close
cooperation with ITU-T SG2, SG11, SG15, SG17, ETSI ISG-QKD, ISO/IEC JTC1/SC27,
AG4, IETF/IRTF, and relevant groups for future standardization on QKD networks.