Practical Runtime Enforcement of First-Order Temporal Requirements

2026-10-03

AI Summary

This study addresses the performance limitations of existing runtime enforcement mechanisms in handling complex temporal compliance requirements, which often fail to meet real-time demands in production environments. To overcome these challenges, this work proposes a compilation-based efficient execution paradigm. Specifically, it identifies an executable subset of Metric First-Order Temporal Logic (MFOTL) that balances rich expressiveness with low runtime complexity. By leveraging compiler optimization techniques, temporal logic specifications are directly compiled into imperative programs, thereby circumventing the performance bottlenecks inherent in traditional interpreters and yielding a high-performance execution engine named EnfFlash. Experimental results demonstrate that this approach reduces latency by 44 times up to three orders of magnitude compared to state-of-the-art tools. Furthermore, enforcing GDPR policies in web applications incurs merely 15ms of overhead, validating its practical viability for industrial deployment.

Abstract

Runtime enforcers observe a system's behavior and exert control over it to ensure that the system always adheres to its requirements. Many natural requirements not only formulate restrictions on the system's present behavior, but also impose obligations on its future behavior; for instance, agentic security may require personal data collected during a run to be erased by some deadline. In an ever-growing compliance landscape, real-world systems may be subject to hundreds of such requirements. However, existing enforcement mechanisms supporting complex policies are often too slow for production software; instead, developers may resort to non-temporal access control mechanisms and ad-hoc instrumentation, but these scale poorly with requirement complexity. To address this problem, we introduce an efficient algorithm and tool for enforcing complex temporal requirements and demonstrate its performance. Specifically, we identify a fragment of Metric First-Order Temporal Logic (MFOTL) that can be enforced with low runtime complexity while supporting a rich family of practically relevant requirements, including obligations. We then design an enforcement algorithm for this fragment and implement it in EnfFlash, a novel tool that enforces requirements with latency up to 44x lower than EnfGuard, the previous state-of-the-art enforcer, on standard benchmarks, and up to three orders of magnitude lower on security policies for LLM agents. This performance is achieved by compiling requirements into imperative programs that we efficiently interpret. We evaluate EnfFlash both standalone, on existing benchmarks, and integrated in web applications as an enforcement backend. We demonstrate that it can enforce a substantial 400-line MFOTL formula specifying the GDPR on a social network while adding under 15 ms to each page view, which is sufficient for most interactive and real-time applications.

Problem

• Runtime Enforcement
• First-Order Temporal Logic
• Compliance Monitoring
• Performance Scalability
• Metric First-Order Temporal Logic

Innovation

• Runtime Enforcement
• Metric First-Order Temporal Logic
• MFOTL Compilation
• EnfFlash
• LLM Agent Security