Guide: Verify a source¶

What is this?¶

Check that a Receipt v1 envelope is intact under a public key you trust — signature, content hash, optional Merkle root, optional watch-chain links.

This is integrity vs key, not proof that the page said what was extracted or that the key belongs to anyone in particular.

When should I use it?¶

You need tamper-evidence beyond “the chat said so”: audits, RAG freshness checks, sharing citation packages, or confirming a hand-off capsule's signed core.

Minimal example¶

{
  "name": "occam_verify",
  "arguments": {
    "receipt": "{ … receipt from transcode … }",
    "markdown": "# page text …",
    "mode": "offline",
    "public_key": "-----BEGIN PUBLIC KEY-----\n…"
  }
}

When verifying a receipt from another Occam install, always pass that install's public key PEM. Omitting public_key on MCP defaults to this host's key — fine for self-checks, wrong for third-party verification.

Human overview: Receipts · Normative: Receipt verification

Expected result¶

Fields such as signatureValid, contentHashMatch, and a verdict:

Verdict (examples)	Meaning
`verified`	Signature valid under the supplied key; optional hash match
`wrong_key`	Signature fails under this key; claimed `keyId` differs from local
`signature_invalid`	Signature fails; same-key tamper suspected
`history_verified`	Watch chain linked and every entry signed
`history_chain_ok`	Watch chain linked but unsigned entries present

verified means bytes and key — not truth, origin, or identity.

MCP vs CLI¶

Capability	MCP `occam_verify`	CLI `OccamMcp.Core verify`
`--pubkey` / `public_key`	Optional (defaults to local host key)	Mandatory
Dataset manifest verify	Not available	`--mode manifest`
Live drift / prove	Yes	No
Time anchor gates verdict	No (reported only)	Yes for `verified`

What can go wrong?¶

Missing or wrong public key (foreign receipt verified against local key)
Truncated receipt JSON or blockLeaves that do not reconstruct the signed root
Markdown that does not match the signed contentHash (different budget/fit/focus than original extract)
Treating Merkle citation as proof the quote supports your claim