# Confidential Evidence

URL: https://docs.nexart.io/docs/evidence-bridge/confidential-evidence

Evidence Bridge seals protected content as keyed, salted HMAC commitments before attestation, keeps private openings separate from the public record, and supports later selective verification.

A confidential CER contains commitments. The private opening contains the information necessary to verify a committed value. Conceptually:

Public CER

```
{
  "commitment": "hmac-sha256:..."
}
```

Private opening

```
{
  "field": "preState",
  "salt": "...",
  "value": {
    "status": "ONLINE"
  }
}
```

## How openings are handled

The opening is not sent to the NexArt Node. Openings are:

- tenant-scoped
- record-family-scoped
- stored separately from public CERs
- excluded from public APIs
- excluded from normal result responses
- never logged

## Selective verification

A verifier with the correct opening can verify that the disclosed value matches the commitment in the certified record. A wrong opening fails verification.

NexArt confidentiality uses keyed, salted HMAC commitments managed by the canonical SDK. This is not encryption, and a plain SHA-256 hash does not provide confidentiality.

For the underlying commitment scheme, domain separation and the V2 sealing API, see Confidential Mode.