The Reality of Algorithm Agility: Studying the DNSSEC Algorithm Life-Cycle

The DNS Security Extensions (DNSSEC) add data origin authentication and data integrity to the Domain Name System (DNS), the naming system of the Internet. With DNSSEC, signatures are added to the information provided in the DNS using public key cryptography. Advances in both cryptography and cryptanalysis make it necessary to deploy new algorithms in DNSSEC, as well as deprecate those with weakened security. If this process is easy, then the protocol has achieved what the IETF terms "algorithm agility". In this paper, we study the lifetime of algorithms for DNSSEC. This includes: (i) standardizing the algorithm, (ii) implementing support in DNS software, (iii) deploying new algorithms at domains and recursive resolvers, and (iv) replacing deprecated algorithms. Using data from more than 6.7 million signed domains and over 10,000 vantage points in the DNS, combined with qualitative studies, we show that DNSSEC has only partially achieved algorithm agility. Standardizing new algorithms and deprecating insecure ones can take years. We highlight the main barriers for getting new algorithms deployed, but also discuss success factors. This study provides key insights to take into account when new algorithms are introduced, for example when the Internet must transition to quantum-safe public key cryptography.