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What exactly is CurveDNS?

Yep, we can imagine you are asking us this. CurveDNS is the first publicly released forwarding implementation that implements the DNSCurve protocol. Brings us to a new question: what is DNSCurve? Parts of a master thesis have been written to answer this question, but of course there is a short answer. The protocol’s official website gives a pretty good impression in only one sentence: ‘DNSCurve uses high-speed high-security elliptic-curve cryptography to drastically improve every dimension of DNS security’.

What is so special about this implementation is the fact that any authoritative DNS name server can act as a DNSCurve capable one, without changing anything on your current DNS environment. The only thing a DNS data manager (that is probably you) has to do is to install CurveDNS on a machine, generate a keypair, and update NS type records that were pointing towards your authoritative name server and let them point to this machine running CurveDNS. Indeed, it is that easy to become fully protected against almost any of the currently known DNS flaws, such as active and passive cache poisoning.

Features of CurveDNS

CurveDNS supports:

  • Forwarding of regular (non-protected) DNS packets;
  • Unboxing of DNSCurve queries and forwarding the regular DNS packets
  • Boxing of regular DNS responses to DNSCurve responses;
  • Both DNSCurve‚Äôs streamlined- and TXT-format;
  • Caching of shared secrets;
  • Both UDP and TCP;
  • Both IPv4 and IPv6.

So what about DNSSEC?

You’re right, DNSSEC was designed to do exactly the same thing. So why should you be using DNSCurve instead of DNSSEC? The short answer: because it is better in many ways. The longer answer involves some more knowledge about things DNSSEC does not fulfill that well. One of the most important ‘flaws’ of DNSSEC is so called amplification. This means that a DNSSEC capable authoritative name server can be used as a ‘amplification target’. For example, sending a 31 byte query to a certain DNSSEC capable host (i.e. an authoritative name server), can result in a 3.974 byte response. In this way, traffic grew with a factor of around 128. Meaning an attacker with a 1Mbit/s connection can theoretically generate a UDP flood of 128Mbit/s.

Nevertheless, CurveDNS is able to forward DNSSEC packets too. Meaning that if you put CurveDNS in front of a DNSSEC competent authoritative name server, you have enabled your DNS data to be DNSSEC and DNSCurve capable.

What is ON2IT.net?

ON2IT.net is a Dutch company that delivers managed computer security services to a wide variety of customers. They support CurveDNS in several ways. Firstly, because they gave a student the opportunity to design, built, and analyze a DNSCurve implementation to accomplish his master study — which is exactly the implementation offered by this website. And secondly, for hosting CurveDNS’ place on the web.