Skip to content
1,322,867 nurse-staffing records · CMS PBJ
fonteum
DataAPIRisk SignalsResearchCompareSnapshotsRequest access →

Compliance posture

Methodology · Corrections log · Editorial policy

fonteum

Product

  • Data
  • API
  • Methodology
  • Sources
  • Freshness
  • Citations

For buyers

  • AI agents
  • RAG developers
  • Compliance
  • Researchers
  • Developers

Reference

  • Compare
  • llms.txt
  • Agent card
  • Audit pack
  • Quality scorecard
  • Pilot intake
  • Research

Sourced from federal agencies. Fonteum, Inc., Delaware C-corp. © 2026.

Request access→

Trust → Integrity → Chain

Attestation chain head.

Every snapshot Fonteum publishes is SHA-256 hashed at write time and appended to a Certificate-Transparency-style log. The head of that log — the most recent attestation — is published below. Once the per-snapshot previous_link_hash backfill lands under §sprint3-attestation-chain, every row will additionally chain backwards to the prior row, making any tampering detectable by a single recomputation.

Current head
snapshot_id
24
source_id
cms-outpatient-utilization
snapshot_date
2026-05-31
content_hash (SHA-256)
f55bb4f38924fc319fcbdac42a1d95ad7c0edd9f0c4d32eb5697bbe9136033a0
attested_at
2026-05-31T06:40:03.590853+00:00
previous_link_hash
(deferred — §sprint3-attestation-chain)
signing_key
(STH signing key publishes with first signed tree head)

Total attestations on file: 10

Witness co-signatures — snapshot 24

No witness signatures on file for this snapshot.

Verify this snapshot programmatically: /api/attestation/verify/24

How the chain works

  1. Each upstream archive is downloaded, SHA-256 hashed, and written to snapshot_attestations with the source archive URL preserved verbatim.
  2. Each new row carries a previous_link_hashfield set to the prior row's content_hash (or all-zero for the first row in a source family). Tampering with any historical row breaks every downstream link.
  3. A periodic STH (Signed Tree Head) seals the chain head with Fonteum's chain-signing public key. Verifiers fetch the STH, walk the chain backwards, and confirm every link.
/verify — re-hash any attested snapshot →/trust/integrity — full attestation index →/docs/cache — 90-day source mirror →