A Self-Adaptive Slice-Conditioned Trust Scoring and Containment Framework for Zero-Trust 6G Networks

Zero trust is increasingly considered a key security paradigm for sixth-generation (6G) networks, yet most existing approaches emphasize architecture while leaving continuous trust adaptation and its interaction with slice-level service requirements insufficiently addressed. This paper presents SENTRA (Slice-conditioned Evaluation of Network TRust and Adaptive containment), a self-adaptive continuous trust scoring and containment framework for zero-trust 6G network slices. SENTRA fuses five security evidence streams into a Beta-distributed trust state and dynamically adjusts its forgetting factor according to both slice risk class and observed evidence volatility, enabling a single trust engine to adapt its behavior across ultra-reliable low-latency communication (URLLC), enhanced mobile broadband (eMBB), and massive machine-type communication (mMTC) slices. To support resilient runtime enforcement, the framework employs an asymmetric hysteresis controller with dwell confirmation and a damped inter-slice trust coupling mechanism. We derive an upper bound on steady-state false containment and establish a spectral-radius condition that prevents cascading containment across interconnected slices. Simulation experiments involving 500 devices, six slices, 5000 epochs, and 30 independent seeds evaluate SENTRA under abrupt compromise, slow-ramp stealth, on–off oscillation, and cross-slice pivot attacks. SENTRA achieves the lowest overall operator objective across the four tested adversary profiles while producing distinct operating points according to slice service requirements. The results also reveal limitations under conservative URLLC configurations and cross-slice pivot attacks, highlighting the trade-off between responsiveness, availability, and containment effectiveness. These findings demonstrate how self-adaptive trust management can provide controlled and analytically grounded security adaptation for resilient zero-trust 6G systems.