A Certainty-Based Approach to Implementing Zero Trust Architecture Using NIST SP 800-207 and NIST SP 1800-35

This paper proposes a certainty-based methodology for implementing the Zero Trust Architecture (ZTA) as defined in NIST SP 800-207 and NIST SP 1800-35 (NIST, 2020; NIST, 2025). By applying a probabilistic model that quantifies the certainty of security-related facts, the proposed approach enhances decision-making for access control and security policy enforcement. This method utilizes major security databases to assess and compute certainty of facts, thereby improving the resilience, adaptability, and accuracy of Zero Trust systems (Liu, Chandramouli, & Kuhn, 2020).