Introduction to Trust Registries

Trust Registries are authoritative, governance-backed directories used within digital ecosystems—whether for API-based data sharing, decentralized identities, AI Agents Ecosystems, or other models. They list trusted organizations and services, verify identity and authorization status, and enable secure, policy-aligned interoperability.

What Is a Trust Registry

A trust registry is a governance-backed, machine-readable directory that lists which organizations, systems, or agents are recognized as trusted participants within a digital ecosystem. This may include those authorized to issue or verify credentials, exchange data over APIs, or act autonomously in environments for AI Agents.

For example, An AI Agent Trust Registry focuses on listing authorized AI agents allowed to operate or make decisions within the ecosystem.

While cryptographic mechanisms (like digital signatures or mTLS) can prove that data hasn’t been tampered with and originates from a known entity, they don’t explain whether that entity is authorized to act. Trust registries add this missing governance layer. They answer critical questions like:

• Who is this party?

• Are they authorized to perform this action?

• Under what policy or trust framework is their authority recognized?

Without trust registries, ecosystems often become fragmented. Relying parties are forced to maintain custom allow-lists, trust decisions become discrete and isolated, and onboarding new participants may be repetitive and error-prone. A trust registry centralizes, decentralizes, or federates these decisions, making trust transparent, scalable, and aligned with shared policies.

Whether in decentralized identity ecosystems, API-based data sharing frameworks, or autonomous AI networks, trust registries help enforce governance and interoperability by maintaining authoritative, cryptographically verifiable information about trusted entities, the scope of their authority, and the actions they are permitted to carry out.

Trust Registry Role and Functionality

Verification and Accreditation

Trust registries verify that entities—such as organizations sharing data, credential issuers, AI agents, or verifiers—are accredited and authorized to perform specific actions within a digital identity or data-sharing ecosystem. For example, before a credential presented to relying party is trusted, a relying party may consult a trust registry to confirm that the issuer is recognized by an authority under a given policy framework.

This accreditation is typically expressed using digital certificates and keys issued by a trusted Certificate Authority (CA - like IACA for MDLs), decentralized identifiers (DIDs), entity statements for OpenID Federation,or other signed artifacts that prove identity, authorization, and accreditation.

Beyond technical identity, trust registries also capture essential contextual metadata—such as an entity’s designated role in the ecosystem. This may include whether the participant is acting as a Data Provider**, Data Consumer, AI Agent, Digital Identity Issuer, or other trusted participant. By publishing this information in a registry, ecosystems can enable scalable, automated trust establishment decisions that align with both security requirements and governance policies, supporting interoperability across sectors and jurisdictions.

Public Accessibility of Trust Information

A core function of trust registries is to provide clear, publicly accessible records that participants can query. This transparency allows relying parties to inspect the origins, accreditations, and current status of credential issuers or AI agents without needing to establish bilateral integrations.

In regulated or high-risk environments—such as healthcare, finance, or AI-driven decision-making—this visibility is crucial for demonstrating compliance, building trust with users, and reducing the risk of relying on unauthorized or malicious actors.

In open ecosystems, this visibility is typically achieved through publicly accessible trust registry panels that display the participants in the ecosystem, along with a machine-readable list of entities, their public keys, assigned roles, and available metadata. This approach enables both human and automated inspection of who is trusted—and under what conditions.

Governance and Accountability

Trust registries serve as enforcement and governance tools that support policy-driven ecosystems. They maintain the history and current state of an entity’s accreditation and can record whether an issuer or agent is currently in good standing.

If an entity fails to comply with ethical, operational, or legal requirements, their status in the registry can be revoked or updated. For example:

• In case of Trust Registries relying on PKIs and X.509 certificates, this means updating Certificate Revocation Lists (CRLs) or Online Certificate Status Protocol (OCSP).

• If a Trust Registry hosts a Trusted List similar to, for example, VICAL or ETSI, it means removal from the trusted list.

  For example, in case of VICAL it is removal of an IACA from the list.

This enables downstream verifiers to reject credentials issued by non-compliant or de-accredited entities, and it provides a clear audit trail in case of disputes or harms caused by credential misuse or AI behavior.

Hierarchies in Trust Registries

Many trust registries follow a hierarchical trust model, inspired by systems like Public Key Infrastructure (PKI). In such a model, a root governance authority accredits intermediary organizations (e.g., professional bodies, regulators, or credential hubs), which in turn authorize subordinate entities such as AI agents or credential issuers.

This multi-level delegation model enables scalable trust without requiring every verifier to directly trust every individual issuer. Trust can be resolved programmatically through cryptographic means, using chains of verifiable credentials and DIDs anchored on decentralized networks or blockchains. The registry helps maintain and resolve these hierarchies, allowing systems to determine whether a given trust chain is valid and policy-aligned.

AI Agent Trust Registries

Trust registries certify AI agents to ensure they meet ethical and compliance standards, helping to establish a verifiable and trustworthy AI ecosystem.

They enable AI agents to prove their accreditation and permissions, allowing relying parties to confirm the legitimacy and scope of an AI agent’s actions.

Decentralized AI agent trust registries use decentralized identifiers and privacy-preserving credentials to provide verifiable identity and auditability for AI agents, ensuring secure and transparent AI interactions.

Trust Registry In the Context of Identity Wallets and Verifiable Credentials

Trust registries list approved issuers authorized to create and sign verifiable credentials. This simplifies trust management for verifiers by providing a centralized or federated source of truth.

Component	Role
Credential	Signed, tamper-proof identity data
Wallet or Holder	Stores and presents credentials
Issuer	Issues verifiable credentials
Verifier	Validates credentials
Trust Registry	Confirms issuer authorization

Trust registries enhance security, privacy, and interoperability in eWallet ecosystems by ensuring that identity wallets rely only on trusted credential issuers.

Trust Registries in Open Data Ecosystems

In open ecosystems, trust registries list approved Data Providers authorized to share data and Data Recipients authorized to access it. This simplifies governance and reduces the need for one-to-one trust agreements.

Component	Role
Data Resource	The shared or exchanged data
Data Holder/Provider	Supplies data to the ecosystem
Data Recipient	Consumes or processes data
Trust Registry	Confirms who is authorized to provide or consume data

Trust registries help open data ecosystems remain secure, scalable, and policy-compliant by maintaining verifiable information about authorized participants.