Patent ID: 11196571

Abstract:
A cryptographic method for signing a message m by a user device on behalf of a group managed by a group manager, which has a secret key generated from two variates x and y, the group having a public key formed from a plurality of elements comprising an element g and an element gz pertaining to a cyclic group of order p, p being a whole prime number and z a variate, and an element h, an element hx, an element h1/z and an element hy/z pertaining to a cyclic group of order p. The method includes: receiving a certificate from the group manager, including elements S1=gr, S2=gr(x+y.u) and S3=gz.r where r is a variate selected by the group manager for the user device; and generating a group signature for the message m, based on the certificate, a variate t generated by the user device, and the secret u.