#digital-signature

The Vue browser application of a document-signing platform: sessions held in memory and renewed by one queued refresh, PKCE sign-in, stamps placed precisely on PDF pages, identity checks with a face challenge, client consent, and role-based administration.

The Laravel core of a document-signing platform: it owns users, identities, organisations, client systems, documents and their signed versions, stamps, and certificates, and orchestrates the services that sign, timestamp, render, and store — without ever holding a file.

A Python service that signs PDFs to PAdES B-LTA with a visible stamp — embedding the timestamp, certificates, and revocation proof, then an archive timestamp — so signatures stay verifiable long after their certificates expire, and verifies signed PDFs.

A Rust timestamp authority that stamps a document's hash with a signed, NTP-backed time per RFC 3161, so PDF signatures stay verifiable after their certificates expire — issuing and renewing its own signing certificate, with public OCSP and CRL.

An issuing certificate authority in Rust that gives each PDF signer a certificate of their own, then answers every reader's question — is it still valid? — through a public OCSP responder and revocation list, and hands the signing service each key and chain as PKCS#12.

The digital signature platform of the City Government of South Tangerang: signers prove who they are, sign PDFs to PAdES B-LTA with certificates from the platform's own authorities, and anyone can verify the result — version 2, which I designed, built and operate.