US 12,476,826 B2
Generating digital signatures
Michaella Pettit, London (GB)
Assigned to nChain Licensing AG, Zug (CH)
Appl. No. 18/682,085
Filed by nChain Licensing AG, Zug (CH)
PCT Filed Jul. 11, 2022, PCT No. PCT/EP2022/069261
§ 371(c)(1), (2) Date Feb. 7, 2024,
PCT Pub. No. WO2023/016730, PCT Pub. Date Feb. 16, 2023.
Claims priority of application No. 2111442 (GB), filed on Aug. 9, 2021.
Prior Publication US 2025/0016008 A1, Jan. 9, 2025
Int. Cl. H04L 29/06 (2006.01); H04L 9/32 (2006.01)
CPC H04L 9/3255 (2013.01) 12 Claims
OG exemplary drawing
 
1. A computer-implemented method, performed by a first participant of a group of a participants, of proving that a target sub-group of the group generated a digital signature, wherein the signature can only be generated based on at least a threshold number of respective signature shares, wherein each participant of the group has a respective private key share of a shared private key, wherein the group is divisible into a plurality of unique sub-groups where each sub-group comprises at least the threshold number of participants, and wherein the method comprises:
for each respective sub-group to which the first participant belongs, generating a respective first ephemeral private key share of a respective shared ephemeral private key, wherein each other participant of each respective sub-group generates a respective ephemeral private key share of the respective shared ephemeral private key;
for each respective shared ephemeral private key, generating a respective shared ephemeral public key;
generating a first signature share of the signature, wherein the first signature share is generated based on a first private key share of the shared private key, the first ephemeral private key share of a target one of the respective shared ephemeral private keys, and a message; and
making the first signature share available to a coordinator for generating the signature based on at least the threshold number of respective signature shares, wherein each respective signature share is based on respective private key share of the shared private key and a respective ephemeral private key share of the target one of the respective shared ephemeral private keys, and wherein the signature comprises a component based on the respective shared ephemeral public key corresponding to the target one of the respective shared ephemeral private keys.