Algorithmic selection of MAC tag length for short messages: balancing the risks of substitution, delay, and throughput

Abstract

In modern telecommunications systems, Internet of Things networks, mobile devices, and embedded sensor platforms, the transmission of short messages with guaranteed integrity and authenticity is a critical element of information security. In such environments, Message Authentication Code is the primary mechanism for protecting against data tampering, but the selection of the optimal tag length remains an open problem. An excessively long tag increases the load on the channel, increases latency, and reduces system throughput, while an excessively short tag significantly reduces resistance to attacks and increases the likelihood of successful spoofing. This problem is particularly acute for short control, telemetry, or synchronization packets, where the tag can constitute a large part of the total data volume transmitted. The research focuses on the algorithmic selection of the tag length, which provides an optimal balance between the level of protection, processing delays, and communication channel efficiency. The study considers the features of using truncated tags. The impact of tag length on the probability of substitution, the frequency of acceptable errors, channel load, and power consumption in resource-constrained systems is analyzed. Risk assessment models are presented depending on the transmission intensity, protocol restrictions, key rotation time, and characteristics of the attack environment. It is shown that for most short messages, truncated tags with a length of 32-64 bits provide optimal security and high throughput, while the use of 96-128-bit tags is justified only in high-risk or mission-critical systems. The practical significance of the results lies in the possibility of using the proposed approaches in the design of modern protocols, industrial networks, wireless sensor systems, and lightweight cryptographic mechanisms, where a combination of high security and transmission efficiency is important.