Communication in the machine-to-everything (M2X) economy, where machines, devices, systems, and humans interact in a highly interconnected environment, is evolving rapidly. Trust among participants is essential for secure operations and data sharing. The multi-factor challenge set self-sovereign identity authentication (MFSSIA) provides an advanced form of identity authentication for securing M2X interactions through verifiable challenge-response mechanisms. In this complex ecosystem, ensuring tamper-proof and reliable interactions is crucial. Current identity authentication systems rely on single sign-on (SSO) or a limited set of predefined challenges, often controlled by governments or large corporations. These centralized systems pose risks such as social discrimination. However, such models lack the flexibility and transparency needed in the M2X environment, where diverse and dynamic actors interact. MFSSIA addresses these limitations through a structured challenge/response lifecycle, where sets are generated, validated, and answered in a decentralized manner using blockchain technology. This removes the need for a central authority while ensuring secure identity validation. This research introduces an MFSSIA challenge/response ontology based on the unified foundational ontology (UFO) to standardize and structure identity interactions. The ontology defines concepts and rules for consistent identity challenge issuance and verification. Additionally, the ontology supports the creation and sharing of secure challenge sets by different companies through a marketplace that ensures their quality and reliability. This approach enhances trust and decentralization in the M2X economy.
Kormiltsyn et al. (2026) studied this question.