Latency-Aware Authentication in Industrial Control Environments: Consequence-Graded Authorization Beyond the Web Latency Budget

Authentication patterns developed for web and cloud environments often assume tens to hundreds of milliseconds of permissible latency per authorization event. Industrial control environments operate on fundamentally tighter budgets: machine vision inspection loops on single-millisecond timescales, programmable logic controller scan cycles in milliseconds, real-time motion-control decisions admitting no perceptible authentication overhead. This paper proposes latency-aware authentication as an adaptive design discipline: authentication strength graded against operational consequence per control cycle rather than applied uniformly. The discipline complements the attacker-class Security Level tiers (SL1–SL4) of ISA/IEC 62443 with an orthogonal consequence-class axis and operates within the operational-technology security framing of NIST SP 800-82r3.