The evidence chain is the trust spine of the CampusPlugin platform. It is an append-only ledger of cryptographic seals — one per stage of a student outcome — that lets a verifier confirm a placement claim without trusting our database.
A chain runs across eight stages: onboarding, readiness, employer verified, application, shortlist, offer, joining, and the final institutional report. Each stage produces a seal of the form HMAC-SHA256 over the local stage payload plus the previous stage seal plus a tenant-scoped key. Break a single stage and every downstream seal stops verifying.
A public verifier route ( /verify ) lets anyone paste a student id or a chain artifact URL and replay the chain in a browser. The renderer never trusts a server-returned boolean. It re-computes every seal locally from the public payload and shows the verifier the line that breaks if any link has been tampered with.
What the chain proves: that the eight stages happened in order, that the payloads on the public side match what was sealed, and that the institution issuing the report stood behind it at the time of sealing.
What it does not prove: a salary number is fair, a job offer is desirable, a student will retain the job. Those are outcomes the chain records — it does not opine on whether they are good ones.