sachi
BRIEFING NOTE
The signature behind Exhibit D
Every provider selling into a US school district signs a student data privacy agreement.
Most sign the National Data Privacy Agreement, and at the end of it sits a form certifying
that student data was disposed of. Signing creates direct obligations on the vendor:
the provider becomes a School Official under FERPA, acting under the district's control, and takes on
disposition duties owed contractually to the district. Nothing in the NDPA specifies what evidence
stands behind that certification.
What the NDPA actually asks for
Exhibit D
Closes with a signature block headed Notice of Verified Disposition of Data,
executed by authorised representatives of both district and provider. The provider certifies
that student data was destroyed, transferred, or de-identified.
§1.1 & Exhibit C
The provider acts as a School Official under FERPA, under the district's direct control
for the use and maintenance of student data. The district remains accountable for its records;
the provider takes on its own duties by contract.
§4.6
Disposition within 60 days of a written request, and again within 60 days of termination.
A district may require the provider's retention and disposition practice in writing, at any time.
Exhibit C
Student Data is defined to include data "gathered, created, or inferred" by the provider.
Inferred data is in scope — reaching learner profiles, behavioural models and embeddings
derived from a student's activity, not only the records a student typed.
Exhibit B
The standard schedule of data lists voice recordings as a collectable category. Under the
amended COPPA Rule, a voiceprint is treated as a biometric identifier and is personal information.
The form asks a provider to certify disposition.
It never asks how disposition was verified.
That is not a defect in the NDPA. Contracts allocate obligations; they do not specify engineering.
But it does mean the strength of the certification rests entirely on what the provider can show.
Why certifying is harder than it looks
Inferred data
Deleting a student's records leaves the embeddings, profiles and model state derived from them — Student Data by the agreement's own definition.
Backups
A 30 or 90 day rotation means a restore can resurrect a student disposed of last month. Reaching backups is where most deletion routines stop.
Subprocessors
§2.3 requires subprocessors be bound to terms no less stringent. Disposition has to propagate to every vendor holding a copy.
The attestation is not tested in the ordinary course. It is tested after an incident.
In practice a signed Exhibit D is rarely questioned at the time. Where practitioners
report it surfacing is after a breach: when data appears that should have been disposed of, the
certification stands as the record of what was represented, and by whom.
sachi
BRIEFING NOTE — 2
What provable disposition looks like
Chasing every copy of a student's data across databases, indexes, warehouses and backups is difficult
to do and harder still to evidence. Encrypting per student and destroying the key inverts it: one act,
one record, every copy unreadable at once.
We hold the keys. We never hold the data.
Student data is encrypted by our SDK inside your application, before it is first written, and stored
as ciphertext in your own infrastructure. Sachi holds only the per-student keys — so adopting
us narrows your subprocessor surface rather than widening it, and a breach of Sachi exposes no readable
student record.
YOUR SYSTEMS
Plaintext in memory during a session. Ciphertext at rest — records, embeddings, backups.
SACHI
Keys, consent state, retention policy, audit chain. No student data, ever.
One call, and the evidence is generated
# Disposition on request — or automatically at retention expiry
resp = sachi.students.delete(
student_id="stu_84f2",
reason="lea_disposition_request",
)
# => status: "key_destroyed" · scope: records, embeddings, backups
# objects_unreadable: 1284 · completed_at: 2026-08-18T14:22:07Z
# certificate_url: "api.getsachi.ai/v1/certificates/a7f3..."
Against the agreement
| NDPA obligation | What a provider can show |
| Exhibit D — Notice of Verified Disposition |
A signed certificate naming subject, method, scope and timestamp, referenced to a tamper-evident log entry rather than to an assertion. |
| §4.6 — disposition within 60 days |
Key destruction is a single operation, with its completion time recorded. Retention expiry is enforced on every stored item rather than run as a periodic sweep. |
| Exhibit C — inferred data in scope |
Embeddings and derived profiles are encrypted under the same per-student key, so they die with it. Nothing is hunted down separately. |
| §5.3 & Exhibit F — recognised framework |
Cryptographic erasure is a recognised media sanitisation technique in NIST SP 800-88, the standard the NIST frameworks listed in Exhibit F draw on for sanitisation controls. |
Three questions worth asking internally
- When we sign Exhibit D, what could we produce if a district asked how disposition was verified?
- Does our deletion routine reach inferred data — embeddings, profiles, model state — or only source records?
- If a backup were restored tomorrow, would a student we disposed of last month come back?
The API is available for drop-in technical pilots. If those questions are worth an
hour of an engineer's time, we are running a small number of scoped pilots with teams selling into districts.