Verify

Verify a writing certificate

Name: Core
Price: 1200 JPY
Availability: InStock
Author: noform

Upload a certificate PDF exported by Core to check whether the signature is genuine and the text is unchanged.

Drop a certificate PDF here, or click to choose

Choose the “Writing Certificate.pdf” exported by Core. The file is verified right here in your browser.

What this check tells you

Whether the certificate is genuine — it’s signed with a key (Ed25519) inside Core. The public key confirms it, so forgeries made outside Core won’t match.
Whether the text was changed — the certificate includes a code of the text (SHA-256 hash) and the verdict, signed together. Edit the text afterward and verification fails.

For the full explanation, see Writing Certificate.