Resolver-side validation is now live
Cloudflare says its 1.1.1.1 public resolver now validates DNSSEC signatures made with ML-DSA-44, the post-quantum digital-signature algorithm standardised by NIST. Users of 1.1.1.1 do not need to enable a setting: when a DNSSEC zone publishes the relevant records, the resolver can verify the ML-DSA-44 path alongside conventional DNSSEC algorithms.
The size change is substantial. Cloudflare measures an ML-DSA-44 signature at 2,420 bytes and its public key at 1,312 bytes, compared with a 64-byte signature and 64-byte public key for ECDSA P-256. That can push DNSSEC responses beyond normal UDP budgets, causing authoritative servers to return truncated responses and resolvers to retry over TCP or another transport.
Cloudflare adds a stricter downgrade rule
Running conventional and post-quantum signatures together is necessary while older resolvers remain in use, but it creates a downgrade problem. Standard DNSSEC validation can accept any valid supported path. If a future attacker could forge the conventional algorithm, a post-quantum-capable resolver might otherwise accept that weaker path even though a stronger one was published.
Cloudflare says 1.1.1.1 applies a stricter local policy when an authenticated parent DS record indicates a supported post-quantum algorithm. In that case at least one ML-DSA-44 validation path must succeed; a valid conventional path alone is insufficient. The policy uses the parent delegation as the signal that post-quantum validation is expected.
The chain of trust is still incomplete
Resolver support is only one part of DNSSEC deployment. Authoritative DNS software must sign zones with ML-DSA-44, registrars must accept the corresponding DS records, registries must publish them, and the chain must eventually extend through the DNS root. Any parent level that remains protected only by a quantum-vulnerable algorithm remains a downgrade point.
Cloudflare says its next steps are ML-DSA-44 signing in Cloudflare Authoritative DNS and DS-record support in Cloudflare Registrar. Until equivalent support reaches the wider delegation chain, describing 1.1.1.1 as providing end-to-end post-quantum DNSSEC would overstate what has shipped.
Why early deployment matters, and what it does not prove
Cloudflare is using the resolver rollout to measure operational effects such as signature-verification cost, extra bandwidth and additional TCP use. Those are material constraints because post-quantum DNSSEC messages are much larger than today’s common signatures and can expose assumptions in DNS software and networks.
No cryptographically relevant quantum computer is known to exist today, and DNSSEC protects authenticity rather than confidentiality, so this migration does not address a harvest-now-decrypt-later threat. The value of the deployment is operational preparation: testing a standardised algorithm at resolver scale before a complete post-quantum DNS hierarchy is required.