Cloudflare Adds Post-Quantum DNSSEC Validation to 1.1.1.1

Cloudflare says 1.1.1.1 now validates DNSSEC signatures created with ML-DSA-44, a post-quantum algorithm standardized by NIST. The rollout gives the DNS ecosystem an early, internet-scale test of technology intended to withstand future quantum attacks.

The change matters for anyone building AI services, APIs, or cloud applications because DNS remains part of the chain that directs users and services to the right infrastructure. DNSSEC helps resolvers verify that responses have not been forged or altered. Cloudflare is targeting full post-quantum security by 2029, but migrating DNSSEC will require coordination among authoritative servers, registries, registrars, and resolvers.

The size problem

ML-DSA-44 signatures are 2,420 bytes—almost 38 times the size of an ECDSA P-256 signature, which is 64 bytes. The post-quantum public key is 1,312 bytes. A signature alone can exceed common DNS-over-UDP budgets, including the widely used 1,232-byte limit, before the response contains any DNS records or protocol overhead.

Rather than relying on fragmented UDP packets, authoritative servers may need to signal truncation and make resolvers retry over TCP. Around 85% of queries reaching 1.1.1.1 currently arrive over UDP, making transport behavior a practical concern. DNSKEY responses are especially challenging because they may temporarily include both conventional and post-quantum keys and signatures for compatibility with older validators.

Quantum computers capable of breaking today’s DNSSEC algorithms do not exist yet. Cloudflare’s move is therefore less about an immediate threat than gathering operational data early—before large responses, fallback behavior, and years-long compatibility requirements become urgent migration blockers.

Source: CloudFlare