Patent ID: 8199910
Filing Date: 2012-06-12
Classification: H04L

Abstract:
1. A signature generation apparatus generating signatures for a group signature, the group signature being subject to: a predetermined bit-length K[n]; a predetermined bit-length K[l]; a predetermined bit-length K[e]; a predetermined bit-length K[e′]; a bit-length K[q] of a prime number q denoting the order of a finite group GG defined by an elliptic curve; an output bit-length K[c] returned by a hash function Hash applied to a bit sequence of arbitrary length; a bit-length K[S] such that when a random number r of bit-length |a|+K[S] for any integer a is selected, then a+r and a are statistically indistinguishable; security parameters K=(K[n], K[l], K[e], K[e′], K[q], K[c], K[S]); an integer λ=K[n]+K[q]+K[S]; a set of integer values Λ in a range from 0 (inclusive) to 2 scalar multiplication [c](·) on the elliptic curve; and point addition + wherein an Issuer's key pair for the group signature comprises wherein an Opener's key pair for the group signature comprises: wherein a User-Revocation manager's key pair for the group signature comprises: wherein an i-th User's key pair for the group signature comprises: wherein the signature generation apparatus generates a signature for a message m from the i-th user, the signature generation apparatus comprising: wherein, among the above computations, any two or three of a[1] wherein one or a plurality of RSA computing circuits compute the modular exponentiation and modular multiplication operations, wherein an elliptic curve computing circuit computes the scalar multiplication [c](·) on the elliptic curve and the point addition + wherein a hash computing circuit computes the hash operations, and wherein a single bus transfers computational results among the elliptic curve computing circuit, the one or the plurality of RSA computing circuits, and the hash computing circuit.