Key concepts
This page summarizes ideas behind Portable Trust Infrastructure (PTI). For definitions, see the Glossary. For the category thesis, see Why PTI exists.
Portable Trust Infrastructure (PTI)
PTI is an infrastructure layer for trust — not a credit bureau, social network, or star-rating app. It lets trust signals travel with a subject across life-area contexts instead of being locked in one institution’s silo.
| Role | Responsibility |
|---|---|
| Trust producer | Ingests verified activity as trust events |
| Trust exchange | Normalizes, governs, and routes signals |
| Trust consumer | Runs trust lookups at decision time |
| Trust registry | Maintains pti_id, contexts, and policies |
Trust contexts
PTI isolates signals and scores by trust context (lending, rental, employment, insurance, merchant, civic, and cross-cutting lenses such as risk compliance). The trust context catalogue documents 20+ registered contexts in the reference architecture.
Implementations MUST NOT collapse unrelated life areas into a single opaque score without an explicit, published aggregation policy.
Trust profile and lookup
A trust profile is the aggregate view of a subject’s signals, context scores, relationships, and assertions. A trust lookup is a consumer’s decision-time request to evaluate that profile for a bounded purpose — not a traditional credit bureau file.
Lookup tiers (Basic, Detailed, Predictive, Screening) differ in depth; all are trust intelligence exports with explainability requirements per RFC-004.
Signals, evidence, and explainability
Trust events become normalized trust signals with provenance. Trust evidence substantiates assertions and outcomes. Consumers receive drivers, confidence bands, and coverage gaps — not black-box clearance. See Explainability guide.
Machine learning MAY support signal fusion and identity resolution; outcomes MUST remain structured and auditable.
Governance
Consent, retention, purpose binding, subject rights, and audit obligations are specification requirements — see RFC-007 Governance and Specification governance.
Participants
| Participant | Role in PTI |
|---|---|
| Subjects | Portable pti_id; consent and rights under governance |
| Trust producers | Emit verifiable events and assertions |
| Trust consumers | Request context-scoped lookups |
| Implementers | Operate exchange, registry, graph, and intelligence services |
Reference implementation
TumiTrust demonstrates these concepts in production. Product-specific integration guides live under TumiTrust documentation.