# A provenance vector for the reach conformance runs

`captured.jpeg.wai` is a `wai.image.jpeg` envelope and `captured.receipt.json` its signed
asset-provenance receipt (`wai::provenance::AssetReceipt`): three steps
(`origin.synthesize`, `encode.png`, `encode.jpeg`), a Merkle root over them, the total
joules, and an Ed25519 signature. Its pixels are a synthesized pattern (rings and a
gradient), not a photograph.

**Provenance.** Both files are written by `wai_prov` (`wai-rs/src/bin/wai_prov.rs`), which
synthesizes the pixels, encodes them to PNG and then to JPEG, wraps the JPEG and signs the
lineage. The key is the tool's published test seed, the byte `0x70` repeated 32 times
(public key `19204c8c…ef067791`), and the `signer_id` is the tool's label,
`did:example:wai-prov`: a key whose seed is published attests nothing, so its id names no
origin (jwp-receipts §7.1, §7.8). The figures, 426844 µJ for `encode.png` and 140425 µJ
for `encode.jpeg` (unlabelled; `origin.synthesize` is unmetered), are the ones `wai_prov`
bracketed when it first wrote this asset, at an earlier revision that signed under an
origin-bound id. Its samples were the processor power a non-privileged reader reports, not
a counter it read and showed live, so the figures are `ModelBased` at best
(energy-measurement §3.1); being unlabelled, the receipt states no class. `--carry` carries them onto the same bytes
and signs them again under the label; nothing is measured again. `wai_prov` carries a
figure only from a receipt that verifies and whose steps have this run's operations, input
and output hashes and work.

To regenerate, from `wai/wai-rs` (the `codecs` feature links the system codec libraries):

```
cargo run --release --no-default-features --features provenance,codecs,receipt_claims --bin wai_prov -- \
  ../wai-web/reach/test/vectors/provenance \
  --carry ../wai-web/reach/test/vectors/provenance/captured.receipt.json
```

The receipt is carried onto itself, so the command writes both files again byte for byte;
on a host whose synthesis or encoders give other bytes, the lineage differs and the
command refuses. Without `--carry`, `wai_prov` brackets each encode afresh (a usable
figure is labelled `ModelBased`), and the receipt and its hash below change.

The receipt profile of the reach builds exists to check receipts like this one, so the
conformance runs (`../../conformance.js`) verify it on every rung: the content hash and
the signature must verify, a copy with one bit changed must fail the content check, and
a copy with its joule total raised by one must fail the signature check. The receipt's
hash, signer id, step count and joule total must read as the receipt states them; the
total crosses the JavaScript boundary as a 64-bit integer, a `BigInt` where the engine has
one and a `Number` where it does not.

| file | SHA-256 |
|---|---|
| `captured.jpeg.wai` | `4382082d2bbd1ef5358315afd578fc533d74bf973a57d4c45033c89c847a22a3` |
| `captured.receipt.json` | `97c5c24a03eae1c6a2d0e5374ad13c5ca00de00d696f40116f41c66b7097ff64` |