Field Experiments on Post-Quantum DNSSEC

We have conducted a field study on post-quantum DNSSEC [1], involving RIPE ATLAS measurements with around 10,000 probes. Using implementations of post quantum signing schemes (Falcon, Dilithium, SPHINCS+, XMSS) in both BIND and PowerDNS, DNS response success and failure rates depending on the signing scheme and other parameters were investigated. In addition to the above algorithms, we present new results on a novel class of DNSSEC signatures, using Merkle trees for optimizing signature sizes. Besides measurement results, we also provide context on our implementation approach. We find that depending on circumstances, a significant fraction of clients choke. Failure rates are mainly a function of response packet size, which is mediated by parameters such as DNSSEC configuration (KSK/ZSK vs. CSK, NSEC vs. NSEC3, or compact DoE) and DO bit presence, with some variation depending on transport. This is qualitatively in line with the "educated guess", but adds quantitative detail. We also find surprising results, such as that a number of resolvers claim to have validated PQC signatures, even though it is implausible for resolvers to support these algorithms. Between now and RWC 2025 we will be evaluating all of the above algorithms in the context of a large enterprise’s DNS environment, which will further enhance our understanding of the implications of transitioning to quantum safe algorithms. Implementation included adding both signing and validation support to PowerDNS recursor and BIND resolver. Both functions can be tested using a do-it-yourself frontend [2], which the public can use to work and familiarize themselves with our testbed. We hope that this study helps inform future PQC engineering developments not just in the context of DNS but also other UDP based protocols [1]: https://nlnet.nl/project/PQ-DNSSEC-Testbench/ [2]: https://pq-dnssec.dedyn.io/