Further results on asymmetric authentication schemes

This paper derives some further results on unconditionally secure asymmetric authentication schemes. It starts by giving a general framework for constructing A2-codes, identifying many known constructions as special cases. Then a full treatment of A3-codes (A2-codes protecting against arbiter's attacks) is given, including bounds on the parameters and optimal constructions. With these models as a basis, we proceed by giving constructions of general asymmetric authentication schemes, i.e., schemes protecting against specified arbitrary sets of participants collaborating in order to cheat someone else. As a consequence, we improve upon Chaum and Roijakkers interactive construction of unconditionally secure digital signatures and present a (noninteractive) construction in the form of a code. In addition, we also show a few bounds for this general model, proving the optimality of some constructions