Model-based protocol engineering: Specifying Kerberos with object-process methodology

We overview and demonstrate a framework for model-based protocol engineering. Engineering standards, protocols, and standardized procedures, especially in computing and communication, must be structured, well-defined, and simple to understand, so they can gain wide acceptance and adoption. Yet, standards and protocols often lack an underlying formalism required to ensure their integrity, consistency, and traceability. Lack in these aspects can cause delay in standard publication, distribution, adoption, implementation, and utilization, and might discredit the standard and harm its sponsors´ reputation. Model-based protocols are easier to understand, implement, test, and integrate with existing products, solutions, and systems. Our approach draws on the recently adopted ISO 19450 standard of Object-Process Methodology (OPM) - a holistic systems engineering paradigm for modeling complex, dynamic systems. We demonstrate the benefits of our model-based approach by employing OPM to specify the widely-accepted Kerberos protocol for networked computer user and device authentication.