Aggregate Message Authentication Codes

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This paper proposes and investigates the notions relating to Aggregate Authentication Codes (MACs). These have the property of aggregating multiple MAC tags to form a shorter tag that maintains its ability to be verified by a recipient sharing a unique key with each of the senders. The paper suggests aggregate MACs as a suitable tool for authenticated communications in ad-hock mobile networks or other settings that have the resource - constrained devices sharing unique keys with a common entity like a base station, and communication is expensive. It formally introduces notions of aggregate MACs and presents the first detailed study relating to it. Appropriate definitions are followed by a highly efficient yet simple construction of aggregate MACs founded on the existing MACs. It also makes critical evaluation of the system. It is remarked that their existence is somewhat unexpected since algebraic properties of the mentioned signature scheme are used to aggregate in the backdrop of aggregate signatures. In contrast, number- theoretic constructions along with base aggregate MACs on block like functions are avoided because of their limited algebraic structure. To conclude, the paper proves the theorem (put in simple words) - if a secure message code exists, then a secure aggregate message authentication code also exists, bound by some complexities.