Anonymity in Shared Symmetric Key Primitives

We provide a stronger definition of anonymity in the context of shared symmetric key primitives, and show that existing schemes do not provide this level of anonymity. A new scheme is presented to share symmetric key operations amongst a set of participants according to a (t, n)-threshold access structure. We quantify the amount of information the output of the shared operation provides about the group of participants which collaborated to produce it.

Group Testing and Batch Verification

We observe that finding invalid signatures in batches of signatures that fail batch verification is an instance of the classical group testing problem. We present and compare new sequential and parallel algorithms for finding invalid signatures based on group testing algorithms. Of the five new algorithms, three show improved performance for many parameter choices, and the performance gains are especially notable when multiple processors are available.

New Bounds for Generalized Separating Hash Families

The main result of this paper is a necessary condition for generalized separating hash families. We extend previous methods used to obtain upper bounds for separating hash family types {w, w} and {w, w − 1} to the general case {w1, w2,..., wt} for t ≥ 2.

A bound on the size of separating hash families

The paper provides an upper bound on the size of a (generalised) separating hash family, a notion introduced by Stinson, Wei and Chen. The upper bound generalises and unifies several previously known bounds which apply in special cases, namely bounds on perfect hash families, frameproof codes, secure frameproof codes and separating hash families of small type