xlsx_verify_stamp
Verify an Excel workbook's embedded integrity stamp to detect tampering by checking cryptographic signature and hash match.
Instructions
verify a workbook's embedded integrity-verification stamp. Returns whether the cryptographic signature is valid, whether the workbook bytes match what was signed (recomputed hash vs hash IN the stamp), and the full check-result content of the stamp. A workbook can fail verification three ways: (1) no stamp present (file was never stamped, or the stamp was stripped); (2) signature_valid=false (someone modified the claims after signing, or signed with a different key); (3) hash_matches=false (someone modified the workbook bytes after signing). Each is a distinct trust signal.
USE WHEN: the agent (or a downstream verifier) needs to confirm a workbook hasn't been tampered with since it was signed, OR needs to surface the original check results that were attested to. Common scenario: incoming workbook from a counterparty, agent runs verify before trusting any of its values.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| file_b64 | No | ||
| workbook_handle | No |