PaychainX seals every payment in a tamper-evident audit proof. As of this release, the gateway sidecar signs those proofs with ML-DSA-65 (FIPS 204), the NIST post-quantum signature standard, and a signed receipt was independently verified. The in-browser demo below shows the envelope structure; the real ML-DSA-65 signing runs live on the gateway and anyone can verify it.
PaychainX upgraded the post-quantum gateway sidecar from hash-only proofing to ML-DSA-65 signed proof receipts. A signed transaction proof was generated and independently verified through the public verify endpoint, returning valid = true. This moves PaychainX beyond a roadmap-only post-quantum posture to a live, quantum-resistant signature on every proof.
The sidecar performs payload hashing, signed receipt generation, ML-DSA-65 public-key verification, signed routing proofs, signed processor handoff proofs, and signed audit receipts.
Honest scope: signatures are live with ML-DSA-65 in the gateway sidecar, hashing is SHA-256, and ML-KEM (Kyber) key exchange remains roadmap-ready. Anyone can independently verify a receipt by posting its message, signature, and public key to pq.paychainx.ai/verify.
On June 22, 2026 the President signed an Executive Order, Securing the Nation Against Advanced Cryptographic Attacks, directing the move to NIST post-quantum standards. It calls out the harvest now, decrypt later threat, where adversaries capture encrypted data today to break it once a quantum computer exists. The deadlines are concrete:
PaychainX is built for this. The audit envelope already reserves the exact NIST slots, pq_sig: ml-dsa for signatures and pq_kem: ml-kem for key establishment, so the migration is wired into the architecture today, ahead of the federal timeline. A payments platform that can prove a quantum-resistant audit trail is years ahead of processors that have not started. Read the Executive Order.
Every payment commits to a tamper-evident proof: proof_hash = SHA‑256(canonical(payload)), where canonical JSON sorts keys recursively. This reproduces the gateway's real audit proof (hash_algorithm: sha256) in your browser.
The SHA-256 audit above is sealed, and the gateway sidecar now signs that proof with ML-DSA-65 (FIPS 204), the NIST post-quantum signature standard, producing a signed receipt that anyone can verify at pq.paychainx.ai/verify. Web Crypto in the browser cannot run ML-DSA, so this panel demonstrates the envelope shape with an HMAC-SHA512 stand-in for the signature and a hybrid_attestation block. The real ML-DSA-65 signature is generated server-side on the gateway. The envelope shape stays constant, so the migration was drop-in.
Every payment emits a SHA-256 proof_hash over canonical JSON.
The proof record reserves the signature and signature_algorithm fields for the PQ signature.
The sidecar signs each proof with ML-DSA-65, independently verified valid = true.
Set pq_mode to hybrid-enforced so every audit requires a valid PQ signature.
Add ML-KEM (Kyber) for quantum-safe key establishment, plus scheduled key rotation.
Backwards compatible at every step. The envelope shape never changes, so merchants integrate once and the PQ guarantees strengthen underneath them.