(19)

(11)

EP 4 584 928 A1

(12)

(43) Date of publication: 16.07.2025 Bulletin 2025/29 (21) Application number: 23764367.1 (22) Date of filing: 22.08.2023

(51) International Patent Classification (IPC):  H04L 9/40(2022.01) H04L 61/255(2022.01) H04L 61/2521(2022.01) H04L 67/2876(2022.01) (52) Cooperative Patent Classification (CPC): H04L 63/0471; H04L 63/0236; H04L 63/0281; H04L 61/2528; H04L 67/2876; H04L 63/0435; H04L 63/166; H04L 63/045 (86) International application number: PCT/GB2023/052184 (87) International publication number: WO 2024/052640 (14.03.2024 Gazette 2024/11)

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC ME MK MT NL NO PL PT RO RS SE SI SK SM TR Designated Extension States: BA Designated Validation States: KH MA MD TN (30) Priority: 06.09.2022 GB 202213017 (71) Applicant: Arqit Limited London SW1E 5BY (GB)	(72) Inventors: WEBB, David Paul Seaford Sussex BN25 1TJ (GB) GEORGE, Shaun Cardiff CF3 6AH (GB) (74) Representative: Dentons UK and Middle East LLP  One Fleet Place London EC4M 7WS London EC4M 7WS (GB)