Abstract
The emergence of autonomous and semi-autonomous AI agents is transforming distributed computing from conventional service-oriented architectures toward dynamic ecosystems in which software agents can independently invoke models, access data, communicate with other agents, and execute actions on behalf of users or organizations. This evolution creates a security problem that cannot be adequately addressed through static network boundaries or conventional identity mechanisms. Authentication and authorization must instead become continuous, workload-aware, and capable of distinguishing individual agent identities from transient execution contexts. This paper proposes an adaptive zero-trust authentication and authorization framework for AI agent ecosystems based on SPIFFE/SPIRE principles. The proposed approach conceptualizes every AI agent as an independently identifiable workload and combines cryptographically verifiable workload identity with contextual authorization, continuous trust evaluation, least-privilege policies, and adaptive risk decisions. The framework also incorporates computational-efficiency considerations because authentication, policy evaluation, telemetry, and model-mediated security controls can introduce additional processing overhead. The literature indicates that increasingly complex AI workloads require greater attention to computational efficiency, lifecycle management, transparency, and environmental cost (Bartoldson et al., 2023; Menghani, 2021; Schwartz et al., 2020). The study develops a conceptual architecture, identifies its functional components, and evaluates expected security and operational outcomes through analytical scenarios. Findings suggest that SPIFFE/SPIRE-oriented identity can provide a strong foundation for agent authentication, while adaptive authorization is necessary to address dynamic agent behavior, changing context, privilege escalation, and inter-agent delegation. The framework contributes a structured security model for trustworthy agent ecosystems while identifying limitations related to policy complexity, identity lifecycle management, computational overhead, and the absence of standardized behavioral trust metrics.