Skip to main content

Verifiable Trust Components

Verifiable Service (VS)​

A verifiable service (VS) is a service, uniquely identified by a DID, that can authenticate itself to a peer by presenting verifiable credentials before any connection is initiated.

plantuml

tip

Verifiable services can be hosted anywhere, based on service provider (organization, person) decision.

Peers wishing to connect to a VS can review the verifiable credentials presented by the service, verify their legitimacy through trust resolution, and decide whether to proceed with the connection based on the outcome.

A VS is also required to verify the trustworthiness of peers attempting to connect to it, whether those peers are other verifiable services (VS) or verifiable user agents (VUAs), and must reject connections from non-verifiable peers.

Furthermore, if a verifiable service wants to issue credentials or request credential presentation, it must first prove that it is authorized to perform these actions. Otherwise, the peer must refuse the request.

plantuml

tip

All the verifications are performed by the VS by using the trust resolver component. Indexer component is used for service discovery.

Examples of verifiable services include:

  • chatbot services, such as services built for Hologram Messaging
  • decentralized social channels;
  • etc...

Verifiable User Agent (VUA)​

A verifiable user agent (VUA) is software, such as a browser, app, or wallet, designed to connect with verifiable services (VS) and other VUAs. When establishing connections, a VUA must verify the identity and trustworthiness of its peers and allow connections only to compliant VS or VUA peers.

plantuml

As part of this process, the verifiable user agent (VUA) must perform trust resolution by:

  • Verifying the verifiable credentials presented by peers;

  • Querying verifiable public registries (VPRs) to confirm that the credentials were issued by recognized and authorized issuers.

This ensures that all connections are established on the basis of verifiable trust, rather than assumptions.

In addition, VUAs can query an index (the DID directory, managed by the VPR - see below) that catalogs all known verifiable services (VSs), to search VSs compatible with the VUA or VSs that present a certain type of credential. This enables:

  • users to search for and discover relevant services: for example, within a social browser VUA, a user could search for a social channel VS by querying the index for an influencer’s name.

  • VUA vendors to require VSs to present a certain type of credential (free or paid) for being listed in the VUA, of for having specific features in the VUA (premium, etc).

plantuml

Hologram Messaging, a chatbot and AI agent browser, is the first known verifiable user agent.

Verifiable Public Registry (VPR)​

Trust Registries​

A VPR is a “registry of registries”, a public, permissionless service that provides foundational infrastructure for decentralized trust ecosystems, as specified in the Verifiable Public Registry (VPR) specification.

It is used by ecosystems that want to define credential schemas and who can issue or verify credentials of these schemas.

Purpose of a VPR is to answer these questions:

  • is participant #1 recognized by ecosystem E1?
  • can participant #1 issue credential for schema ABC of ecosystem E1?
  • can participant #2 request credential presentation of credential issued by issuer DEF from schema GHI of ecosystem E2 in context CONTEXT?

VPRs are detailed here.

DID Directory​

Added to trust registry features, the VPR provides a DID directory: a public database of DIDs. It allows crawlers and search engines to index metadata associated with verifiable services (VSs) provided by these DIDs.

Trust Resolver​

The Trust Resolver recursively processes the credentials listed in a DID Document, consults relevant VPRs, and returns a concise Proof-of-Trust summary. Callers can then decide whether the resolved DIDs and the services it represents are trustworthy.

Indexer​

A VPR records its state on-ledger, where storage is expensive. Consequently, on-chain entries are kept minimal. The Indexer bridges that gap:

  • Listens to ledger events and fetches every new or updated record.
  • Enriches the raw data (e.g., resolves DIDs, verifies credentials).
  • Builds a compact off-chain index that powers fast, user-friendly queries.

The resulting index lets you search across all ecosystem metadata, including:

  • Ecosystem & Trust Registry details: names, governance-framework versions, credential-schema summaries...
  • DID indexing: every DID found on-ledger is trust-resolved; if it meets the Verifiable Trust spec, its verifiable credential metadata are added to the index.

This approach keeps the blockchain lean while still delivering rich, searchable insight to wallets, services, and analytics tools.