What a certificate is
A signed certificate is a public attestation: a message or a document, signed client-side by your wallet, and entered in the registry under a human-readable serial. The registry stores only public material — the title, the hash of the signed content, your signing address, and the signature itself. For a document, the document's fingerprint (its hash) is recorded rather than the file, so the content stays with you.
How verification works
Anyone holding the certificate's serial can check it: the verifier recomputes the content hash, recovers the signer's address from the signature, and compares both against the registry record and the chain. If one character of the content had changed, the hash would not match; if anyone but the keyholder had signed, the recovered address would differ. Verification is open to the public, without an account — a certificate that only the Republic could check would be a certificate of nothing.
Revocation and standing
A certificate can be revoked by its author, which marks the record without erasing it — history is corrected by addendum, not deletion. Certificates carry the weight of their signer's standing: a forged or fraudulent certificate is a Grade IV offence under the Penal Code. The signature is yours; so is the responsibility.