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Domain Expansion of {MAC}s: Alternative Uses of the {FIL-MAC}

Ueli Maurer and Johan Sjödin

In this paper, a study of a paradigm for domain expansion of MACs is generalized. In particular, a tradeoff between the efficiency of a MAC and the tightness of its security reduction is investigated in detail. Our new on-line single-key AIL-MAC construction, the PDI- construction, transforms any FIL-MAC into an AIL-MAC and is superior to all previous AIL-MAC constructions given in the literature (taking the tradeoff into account). It appears obvious that this construction is essentially optimal.