Signed verdicts

Every result is a signed record of exactly what was checked, how, and what was found, so a verdict can be shown to a client or an auditor and checked by anyone.

signed has four fields: record, signature, kid (which key signed it) and alg (always EdDSA). The signature covers record only.

record holds:

Field	Contents
`id`, `created_at`	The check.
`inputs`	`kind`, `mode`, and `files`: each file's name, size in bytes and SHA-256 fingerprint (never the file itself). Also `spec` (size and fps, if you sent them) and `prompt_sha256` for pre-flights.
`engine`	`version`, the SHA-256 of every model used, and the `settings` that decide a verdict.
`result`	The findings, exactly as returned.
`check_seconds`	How long it took.
`test`	`true` for test-mode checks.

signature is an Ed25519 signature over the record serialised canonically:

JSON with object keys sorted, at every level.
No whitespace: , and : as separators.
Non-ASCII characters written as UTF-8, not escaped ("Zoë", not "Zo\u00eb").
Numbers written the shortest way that reads back as the same double (as Python's repr and JavaScript's Number.toString do), e.g. 0.970673145319531.
The whole thing encoded as UTF-8 bytes.

signature is base64url without padding.

Verify offline

raccord.verify(check)  # fetches the public key from /v1/signing-keys and checks the signature

Or by hand, in Python:

import base64, json, httpx
from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey


def b64(s):
    return base64.urlsafe_b64decode(s + "=" * (-len(s) % 4))  # unpadded base64url


keys = httpx.get("https://api.kolamlabs.ai/v1/signing-keys").json()["keys"]  # a JWK Set
jwk = next(k for k in keys if k["kid"] == check["signed"]["kid"])
body = json.dumps(check["signed"]["record"], sort_keys=True, separators=(",", ":"), ensure_ascii=False).encode()
Ed25519PublicKey.from_public_bytes(b64(jwk["x"])).verify(b64(check["signed"]["signature"]), body)  # raises if invalid

GET /v1/signing-keys returns a JWK Set: {"keys": [{"kty": "OKP", "crv": "Ed25519", "kid": …, "x": …}]}. Pick the key whose kid matches; x is the raw public key, base64url without padding. To ask the server instead: POST /v1/verify with {"record", "signature"}.

Re-run

POST /v1/checks/{id}/rerun runs the check again and compares. The response is {"identical": true, "differences": []} when the inputs, engine and findings match, and the re-run is signed like any check.

If your account keeps media, nothing needs re-sending.
Otherwise, send the same files. They're matched to the record by fingerprint; different files are refused.

Re-runs are charged like a new check. The same files, engine and settings give the same findings.