Provenance

Check any page.

Every page on this site carries a fingerprint of its own contents, a SHA-256 hash. Change one character and the fingerprint changes. Each new version records the fingerprint of the one before it, in a log that is only ever added to.

01 · Check a page

Fingerprint it in your browser.

The check runs in your browser. It fetches the page and the log from this site and sends nothing anywhere.

02 · How it works

What is hashed, and what is logged.

Before hashing, a page drops the parts that describe it: the title block at its foot, the nameplate serial, the revision marks and a few lines of metadata in its head. Those parts carry the fingerprint, so they cannot be part of what it covers. Everything else, every word and every tag, is hashed exactly as it is served.

When a page changes and the change is released, a record is added to the log: the page, its new fingerprint, the fingerprint it replaced, the date and a revision letter. Each record also carries a hash of the record before it. Changing or removing an old record breaks every record after it, and the check above recomputes all of them.

A small triangle with a letter next to a section means that section's text changed in the page's latest revision.

03 · From a terminal

Check it without this page.

curl -s https://celayasolutions.com/hire \
  | perl -0pe 's/<!--prov(:[a-z-]+)?-->.*?<!--\/prov-->//gs' \
  | shasum -a 256

Compare the result with the SHA-256 in the title block at the foot of that page. The whole log is at /provenance/log.jsonl, one record per line.