PTI and Identity Systems
Identity systems answer who is this subject? Portable Trust Infrastructure answers what trust evidence exists for this subject, in which life-area context, with what provenance? They are complementary layers in a modern trust stack.
1. What identity systems are
Identity systems maintain subject directories — registries of people, organizations, and devices with stable internal identifiers, attribute stores, and (often) deduplication logic. Categories include:
- Customer identity and access management (CIAM) — consumer onboarding profiles
- Enterprise directory services — workforce identity (LDAP, Active Directory)
- Customer master data management (MDM) — golden records across CRM and core banking
- Identity resolution platforms — probabilistic matching across datasets
Identity systems optimize for uniqueness, attribute freshness, and account lifecycle within an organization's boundary or federation contract.
2. What problem identity systems solve
| Problem | Identity system response |
|---|---|
| Duplicate accounts | Merge rules, deterministic keys, probabilistic matching |
| Attribute drift | Profile updates, verification timestamps |
| Cross-application SSO | Federated identifiers, token claims |
| Regulatory ID capture | Storage of legal name, DOB, national ID number |
Identity systems excel at account management. They typically do not maintain portable trust history, context-scoped credibility scores, or cross-institutional signal exchange.
3. What PTI adds
Identity systems
- Internal customer or employee IDs
- Attribute profiles and verification status
- Account lifecycle (create, merge, deactivate)
PTI adds
- Portable
pti_id— persists across partners and institutions - Entity linking — maps partner entity IDs to one subject graph
- Trust signal orchestration — events become context-scoped evidence
- Lookup at decision time — institutions consume trust intelligence, not raw PII
PTI treats identity resolution as an input plane. A verified identity assertion may become a trust signal; the PTI-ID becomes the anchor for all subsequent trust events regardless of which partner emitted them.
4. How they compose together
Integration pattern:
- Partner completes identity capture through existing IdP or KYC flow.
- Partner emits a trust event referencing its entity ID and entitled trust context.
- PTI Trust Registry resolves the subject to a
pti_id(creating or linking as needed). - Institution consumers request trust lookups by
pti_id— not by re-querying the partner's identity store.
5. When to use each
| Scenario | Use identity system | Add PTI |
|---|---|---|
| Single-app login and profile | Yes | Optional |
| Multi-partner signal ingestion with portable trust | Yes (per partner) | Required |
| Cross-institution trust lookup at loan/rental/hire decision | Partial (subject match only) | Required |
| Merging duplicate CRM records within one bank | Yes | No |
| Linking repayment history across MFIs and merchants | No (outside scope) | Required |
Rule of thumb: keep your identity stack for authentication and account management; add PTI when trust must travel with the subject across institutional boundaries.
6. Related PTI spec/RFC links
- RFC-011 — Identity Resolution
- Reference Data Model — Subject identity
- RFC-005 — Trust Graph
- Core Design Principles — Portable by Design