EncDNS: A Lightweight Privacy-Preserving Name Resolution Service

Users are increasingly switching to third party DNS resolvers (e.g., Google Public DNS and OpenDNS). The resulting monitoring capabilities constitute an emerging threat to online privacy. In this paper we present EncDNS, a novel lightweight privacy-preserving name resolution service as a replacement for conventional third-party resolvers. The EncDNS protocol, which is based on DNSCurve, encapsulates encrypted messages in standards-compliant DNS messages. User privacy is protected by exploiting the fact that a conventional DNS resolver provides sender anonymity against the EncDNS server. Unlike traditional privacy-preserving techniques like mixes or onion routing, which introduce considerable delays due to routing messages over multiple hops, the EncDNS architecture introduces only one additional server in order to achieve a sufficient level of protection against realistic adversaries. EncDNS is open source software. An initial test deployment is available for public use.