  Aggregation of message authentication codes (MACs) is a proven and efficient
method to preserve valuable bandwidth in resource-constrained environments:
Instead of appending a long authentication tag to each message, the integrity
protection of multiple messages is aggregated into a single tag. However, while
such aggregation saves bandwidth, a single lost message typically means that
authentication information for multiple messages cannot be verified anymore.
With the significant increase of bandwidth-constrained lossy communication, as
applications shift towards wireless channels, it thus becomes paramount to
study the impact of packet loss on the diverse MAC aggregation schemes proposed
over the past 15 years to assess when and how to aggregate message
authentication. Therefore, we empirically study all relevant MAC aggregation
schemes in the context of lossy channels, investigating achievable goodput
improvements, the resulting verification delays, processing overhead, and
resilience to denial-of-service attacks. Our analysis shows the importance of
carefully choosing and configuring MAC aggregation, as selecting and correctly
parameterizing the right scheme can, e.g., improve goodput by 39% to 444%,
depending on the scenario. However, since no aggregation scheme performs best
in all scenarios, we provide guidelines for network operators to select optimal
schemes and parameterizations suiting specific network settings.
