Enc53: DNSSEC-Anchored Stateless Tickets for Post-Quantum Authoritative DNS
DNSSEC authenticates RRsets, but does not provide endpoint authentication or channel security. DNS-over-TLS (DoT) and DNS-over-QUIC (DoQ) can facilitate such needs, but were designed for the stub-to-resolver hop, where stable long-lived connections amortize the expensive initial setup. The recursive-to-authoritative path's high fan-in and nonuniform per-resolver query frequency invert said dynamics. Post- quantum primitives further sharpen this mismatch: an ML-DSA WebPKI certificate chain crosses TCP's initial window, a cold PQ DoQ may incur up to about 140 times the total bytes of the same query over UDP. A survey of TLD and 2LD nameservers further bounds connection lifetimes, with almost half surveyed imposing limits on even non-idle connections. We present Enc53 -- a stateless session ticket protocol enabling efficient authenticated authoritative DNS encryption. Enc53 splits DNS encryption into 2 phases: a short-lived, DNSSEC-anchored, TLS- authenticated provisioning on the initial query in the 1st, and a steady state of 1-RTT AEAD-encrypted UDP DNS queries in the 2nd. Enc53 is server-side stateless: recursive resolvers hold the traffic secret and session ticket, authoritative nameservers hold only a symmetric STEK. We implemented Enc53 in Knot DNS. After provisioning, a steady state Enc53 exchange costs about 570 B -- roughly 3 times a plain UDP query -- and lands within 1 ms of the unencrypted UDP baseline. Resumed PQ-ADoT pays 7.7 times the bytes and 3 times the latency; resumed PQ-ADoQ pays 10 times the bytes for the same latency. When evaluated against a root server query trace, Enc53 achieves 2-fold compute efficiency over ADoT/ADoQ, 3-fold memory efficiency over ADoT, and 12-fold memory efficiency over ADoQ. Finally, when deployed in conjunction with FN-DSA-512 PQ-DNSSEC, the joint Enc53-DNSSEC UDP datagram remains below the 1232B buffer limit.