Aggregate message authentication codes for DAG structures
Kazumune Tanabe, Mitsuru Tada · 2022
A message authentication code (MAC) scheme is a means for verification of a message in a symmetric key setting. An aggregate MAC (AMAC) scheme is proposed for decreasing the communication cost (tag size) generated by plural tag generators. Up to present, we can see an AMAC scheme for parallel construction, one for sequential construction, and one for series-parallel construction. In this paper, we present how to construct and implement an AMAC scheme in which a tag generation order represented by a general DAG is available, and discuss the security and the tag size for the scheme. The first implementation gives a simple HMAC-like AMAC scheme, but the security of such a scheme is shown only under a weak security model. The second one gives an AMAC scheme which is shown to be secure under a strong security model, but the tag size increases in proportion to the number of the paths from the sources to the sinks. Then we discuss also how to decrease the tag size.