Liaison statement
LS on work progress on Quantum Key Distribution (QKD) network in SG11 (as of May 2023) [to ITU-T SG2, ITU-T SG13, ITU-T SG15, ITU-T SG17, ITU-T JCA-QKDN, ETSI ISG-QKD, ISO/IEC JTC1/SC27 and AG4, IRTF QIRG and IETF Opsawg]

ITU-T SG11 is pleased to inform you of our progress on Quantum Key Distribution
(QKD) topics. In the SG11 meeting (Geneva, 10 – 19 May 2023), Q2/11 has made
progress of the following work items.

1. The items approved at the SG11 meeting
There are no approved Recommendations and agreed supplements on QKDN so far.

2. Revised on-going work items

2.1. Draft Recommendation ITU-T Q.QKDN-profr: Quantum key distribution networks
– Protocol framework in SG11-TD453/GEN Recommendation ITU-T Q.QKDN_profr
specifies a framework for signalling requirements and protocols for quantum key
distribution networks (QKDN).

2.2. Draft Recommendation ITU-T Q.QKDN_Ak: Protocols for Ak interface for QKDN
in SG11-TD454/GEN Recommendation ITU-T Q.QKDN_Ak specifies protocols for Ak
interface in quantum key distribution networks (QKDN). Ak is a reference point
connecting a cryptographic application and a key supply function in a KSA. It
is responsible for sending key requests from the cryptographic application to
the KSA, performing authentication between the cryptographic application and
the KSA, and supplying keys from the KSA to the cryptographic application.

2.3. Draft Recommendation ITU-T Q.QKDN_Ck: Protocols for Ck interface for QKDN
in SG11-TD457/GEN Recommendation ITU-T Q.QKDN_Ck specifies protocols for Ck
interface in quantum key distribution networks (QKDN). Ck is a reference point
connecting the QKDN controller control and management function in a QKDN
controller and a KM control and management function in a KM. It is responsible
for the QKDN controller to communicate control information with a KMA and a KSA.

2.4. Draft Recommendation ITU-T Q.QKDN_Kx: Protocols for Kx interface for QKDN
in SG11-TD456/GEN Recommendation ITU-T Q.QKDN_Kx specifies protocols for Kx
interface in quantum key distribution networks (QKDN). Kx is a reference point
connecting two KMs in each QKD node via a KM link. It is responsible for
exchanging information and operations required for key relay, key
synchronization and authentication between KMs.

2.5. Draft Recommendation ITU-T Q.QKDN_Kq-1: Protocols for Kq-1 interface for
QKDN in TD455/GEN Recommendation ITU-T Q.QKDN_Kq-1 specifies protocols for Kq-1
interface in quantum key distribution networks (QKDN). Kq-1 is a reference
point connecting a key storage function in a KMA with a QKD-key supply function
in a QKD module. It is responsible for transferring QKD-keys generated by a QKD
module to the KM.

3. New work items agreed at the SG11 meeting in May 2023

3.1. Draft Recommendation ITU-T Q.QKDNi-profr: Quantum key distribution
networks interworking– Protocol framework in SG11-TD459/GEN Recommendation
ITU-T Q.QKDNi_profr specifies protocol framework including signalling
requirements and protocols for quantum key distribution networks interworking
(QKDNi).

3.2. Draft Recommendation ITU-T Q.QKDN_Mk: Protocols for Mk interface for QKDN
in SG11-TD458/GEN Recommendation ITU-T Q.QKDN_Mk specifies protocols for Mk
interface in quantum key distribution networks (QKDN). Mk is a reference point
connecting the QKDN manager and a KM control and management function in a KM.
It is responsible for the QKDN manager to communicate management information
with a KMA and a KSA.

4. Conclusion
SG11 will study the signalling requirements and protocols of QKDN. Q2/11 looks
forward to close cooperation with ITU-T SG2, SG13, SG15, SG17, ETSI ISG-QKD,
ISO/IEC JTC1/SC27, AG4, IETF/IRTF, and relevant groups for future
standardization on QKD networks.

Attachments:
1) SG11-TD453/GEN: Output – draft baseline text of draft Recommendation ITU-T
Q.QKDN_profr “Quantum key distribution networks - Protocol framework” (Geneva,
10-19 May 2023); 2) SG11-TD454/GEN: Output – draft baseline text of draft
Recommendation ITU-T Q.QKDN_Ak: Protocols for Ak interface for QKDN” (Geneva,
10-19 May 2023); 3) SG11-TD457/GEN: Output – draft baseline text of draft
Recommendation ITU-T Q.QKDN_Ck: Protocols for Ck interface for QKDN (Geneva,
10-19 May 2023); 4) SG11-TD456/GEN: Output – draft baseline text of draft
Recommendation ITU-T Q.QKDN_Kx: Protocols for Kx interface for QKDN” (Geneva,
10-19 May 2023); 5) SG11-TD455/GEN: Output – draft baseline text of draft
Recommendation ITU-T Q.QKDN_Kq-1: Protocols for Kq-1 interface for QKDN
(Geneva, 10-19 May 2023); 6) SG11-TD459/GEN: Output – initial baseline text of
draft Recommendation ITU-T Q.QKDNi_profr “QKDNi - Protocol framework” (Geneva,
10-19 May 2023); 7) SG11-TD458/GEN: Output – initial baseline text of draft
Recommendation ITU-T Q.QKDN_Mk "Protocols for Mk interface for QKDN" (Geneva,
10 - 19 May 2023).