Patent ID: 6411716
Filing Date: 2002-06-25
Classification: G06F,G06Q,H04L

Abstract:
A method for changing the key fragments held by key fragment members in a k-of-n multi-step digital signature system, comprising:(a) selecting a subgroup of k of the n key fragment members; (b) each of the subgroup of key fragment members: (i) selecting a polynomial of degree kâ€²âˆ’1, where kâ€² is not equal to k and is the number of key fragment members needed to generate a digital signature after the change of the key fragments; (ii) computing nâ€² values using the selected polynomial, where nâ€² is the number of key fragment members after the change of the key fragments; (iii) distributing one of the computed values to each of the nâ€² key fragment members; (iv) receiving a computed value from each other member of the subgroup; and (v) combining the received computed values with one of the generated computed values to form a new key fragment; and (c) for each of the key fragment members not part of the subgroup deriving a new key fragment from the received computed values.