US 10,887,110 B2Granted

Method for digital signing with multiple devices operating multiparty computation with a split key

AssigneeUnbound Tech Ltd.

InventorsGeorge Wainblat, Oz Mishli, Guy Pe'er, Valery Osheter, Saar Pe'er, Michael Kraitsberg, Alexander Presman, Yaniv Refael

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Abstract

The present invention disclosed a method operable on a multiparty signing system for performing a multiparty signing act on a digital content. The multiparty signing system disclosed in the present invention comprises at least two multiparty signing servers configured with methods to perform the multiparty signing act of a digital content to sign. The multiparty signing system can be configured to perform the multiparty signing act by a private signing key split to at least two key shares, wherein each key share is held by each of the at least two multiparty signing servers. The multiparty signing system is also configured to communicate with at least one computerized node employed to conduct an approval process for approving the multiparty signing act. The approval process can be configured to conduct the approval process by employing a secure multiparty computation, wherein the approval process is configured to utilize secret shares held by the at least one computerized node. In such cases, the multiparty signing act is approved in case the approval process ended successfully.

Claims16

Dependent claims

A multiparty signing system comprising:

at least two multiparty signing servers configured to perform a multiparty signing act;
a quorum comprising at least two computerized nodes, each node of the at least two computerized nodes stores a share of a secret, said quorum communicating with the at least two multiparty signing servers,
said quorum is configured with instructions to conduct an approval process with the at least two computerized nodes by employing a secure multiparty computation to which the at least two computerized nodes input the shares of the secret and send an output of the approval process to the at least two multiparty signing servers;
wherein the at least two multiparty signing servers are operable on at least one processing unit coupled with at least one memory unit, wherein the at least one processing unit is configured with the instructions to:
obtain a digital content to sign;
approve the multiparty signing act in case the approval process ended successfully;
generate a signed version of the digital content by preforming the multiparty signing act on the received digital content to sign, by the at least two multiparty signing servers and the at least two computerized nodes of the quorum employing a secure multiparty computation, wherein the multiparty signing act is configured to be performed with a private signing key split to at least four key shares, wherein one key share is held by each of the at least two multiparty signing servers and one key share is held by each of the at least two computerized nodes of the quorum;
associate the signed version of the digital content with a public signing key, wherein the public signing key is corresponding to the private signing key split to at least four key shares;
send the signed version of the digital content, and the public signing key to a recipient to verifying that the signed version of the digital content is authentic.

6 more elements

A method for performing a multiparty signing act by a multiparty signing system comprising at least two multiparty signing servers configured to perform a multiparty signing act and a quorum comprising at least two computerized nodes, each node of the at least two computerized nodes stores a share of a secret, said quorum communicating with the at least two multiparty signing servers, comprising:

obtaining a digital content to sign, by the at least two multiparty signing servers;
conducting an approval process by the at least two computerized nodes of the quorum by employing a secure multiparty computation to which the at least two computerized nodes input the shares of the secret and send an output of the approval process to the at least two multiparty signing servers;
approving the multiparty signing act, by the at least two multiparty signing servers, in case the approval process ended successfully;
generating, by the least two multiparty signing servers, a signed version of the digital content by performing the multiparty signing act on the received digital content to sign, by the at least two multiparty signing servers and the at least two computerized nodes of the quorum employing a multiparty secure multiparty computation, wherein the multiparty signing act is configured to be performed with a private signing key split to at least four key shares, and wherein one key share is held by each of the at least two multiparty signing servers and one key share is held by each of the at least two computerized nodes of the quorum;
associating the signed version of the digital content with a public signing key, by the least two multiparty signing servers, wherein the public signing key is corresponding to the private signing key split to at least four key shares;
sending, least two multiparty signing servers, the signed version of the digital content and the public signing key to a recipient to verifying that the signed version of the digital content is authentic.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/199,273Filed 26 Nov 2018
Published: US 2020/0169410 A128 May 2020
Granted: 5 Jan 2021
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H04L 9/3247
Including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity…:…
H04L 9/3255
Involving digital signatures: using group based signatures, e.g. ring or threshold signatures
H04L 9/085
Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for…:…
H04L 9/14
Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols: using a plurality of keys…