Enc53 enables efficient encrypted DNS queries with low overhead
Enc53: DNSSEC-Anchored Stateless Tickets for Post-Quantum Authoritative DNS
Cryptography and SecurityNetworking and Internet Architecture
Summary
Encrypting and securely authenticating DNS queries is important but challenging, especially between recursive resolvers and authoritative servers. The authors found that existing encrypted DNS methods are often too heavy or inefficient for this part of the DNS system. They created Enc53, a protocol that splits DNS encryption into a quick setup phase and a fast, lightweight query phase. This makes encrypted DNS queries much faster and smaller, closer to regular unencrypted queries. Their tests show Enc53 saves computation and memory compared to other encryption methods while staying within DNS size limits.
What this means in practice
- •For dns infrastructure operators: Deploy Enc53 to reduce overhead and latency when encrypting DNS traffic between recursive and authoritative servers.
- •For network security teams: Implement Enc53 to improve DNS confidentiality and authentication efficiency in environments preparing for post-quantum cryptography.
Authors
Minh Hoang Tran, Munshi Rejwan Ala Muid, Taejoong Chung
Abstract
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.