Post-Quantum Content Provenance for a Production News Platform

Every article and op-ed on the site is signed with a hybrid post-quantum signature: ML-DSA-87 (FIPS 204, NIST security category 5) and ED448 (RFC 8032), over a canonical, byte-stable encoding of the stored article and its metadata. The signatures are detached and published at stable addresses. Anyone can check them in a browser, or with any conformant implementation, against a public keyset. That keyset is itself signed by an offline key, and the key identifier is pinned in DNS. The host is commodity shared hosting. It has no native post-quantum libraries, so SHAKE, ML-DSA-87 and ED448 were written in portable PHP. The implementations match an established reference byte for byte. ML-DSA-87 was also checked against NIST ACVP known-answer vectors. The rounding and hint helpers were checked exhaustively: all 8,380,417 residues modulo q, with no mismatches. Signing sits on the publication path. Nothing is stored until it verifies. One ML-DSA-87 signature takes about 17 ms on a single core. Contributor submissions are sealed in the browser with ML-KEM-1024 + P-384, then AES-256-GCM. The server never sees the plaintext. We have not found another news publisher that signs its full article corpus with post-quantum signatures a reader can verify. That is a statement about what we found, not a proof.