US 12,483,396 B2
Key exchange protocol for satellite based quantum network
Andrew Yeomans, Hertfordshire (GB); Omar Iqbal, Hampshire (GB); and Barry Childe, Sussex (GB)
Assigned to Arqit Limited, London (GB)
Appl. No. 18/274,852
Filed by ARQIT LIMITED, London (GB)
PCT Filed Jan. 28, 2022, PCT No. PCT/GB2022/050245
§ 371(c)(1), (2) Date Jul. 28, 2023,
PCT Pub. No. WO2022/162392, PCT Pub. Date Aug. 4, 2022.
Claims priority of application No. 2101310 (GB), filed on Jan. 29, 2021; and application No. 2106979 (GB), filed on May 14, 2021.
Prior Publication US 2024/0129116 A1, Apr. 18, 2024
Int. Cl. H04L 9/08 (2006.01)
CPC H04L 9/0852 (2013.01) [H04L 9/085 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A computer-implemented method of key exchange between a first device and a second device, the method, performed by an intermediary device, comprising:
generating a first intermediate set of symbols based on exchanging first key information with the first device, the first key information comprising data representative of a first set of symbols received from the first device on a first quantum channel, wherein the first device withholds from the intermediary device a first transmitting random basis set used by the first device for transmitting said first set of symbols over said first quantum channel;
generating a second intermediate set of symbols based on exchanging second key information with the second device, the second key information comprising data representative of a second set of symbols transmitted to the second device on a second quantum channel, wherein the second device withholds from the intermediary device a second receiving random basis set used by the second device when receiving said second set of symbols over said second quantum channel; and
sending, to one or more of the first device and second device, a third intermediate set of symbols based on combining the first and second intermediate sets of symbols, wherein each symbol in the first, second, and the third set of intermediate symbols is represented by one or more binary bits;
wherein the first and second devices securely exchange at least first transmitting and second receiving basis information with each other for determining a final shared key based on the first set of symbols, the second set of symbols and the third intermediate set of symbols.