Identifiable abort for a cryptographic method

Abstract

In a lattice based threshold cryptography system each participant provides a share or contribution in the form of a multi-dimensional vector. If dishonest participants collude they can create weaker security by choosing vectors with the same or similar directions (nearly parallel or collinear, see Fig. 1). The invention receives the partial contribution vectors and checks them by comparing their direction with that of the overall vector (arrow in Fig. 3). If their direction is too similar to the overall vector (i.e. it falls within region 30) a protective action (e.g. abort whole procedure or reject partial contribution) is carried out. The invention can provide identifiable aborts for lattice based procedures. [Fig. 3]