One document matched: draft-bortzmeyer-dnsop-dns-privacy-00.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd" [
<!ENTITY rfc1034 SYSTEM "http://xml.resource.org/public/rfc/bibxml/reference.RFC.1034.xml">
<!ENTITY rfc1035 SYSTEM "http://xml.resource.org/public/rfc/bibxml/reference.RFC.1035.xml">
<!ENTITY rfc2119 SYSTEM
"http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml">
<!ENTITY rfc2181 SYSTEM
"http://xml.resource.org/public/rfc/bibxml/reference.RFC.2181.xml">
<!ENTITY rfc4033 SYSTEM
"http://xml.resource.org/public/rfc/bibxml/reference.RFC.4033.xml">
<!ENTITY rfc5246 SYSTEM
"http://xml.resource.org/public/rfc/bibxml/reference.RFC.5246.xml">
<!ENTITY rfc5936 SYSTEM "http://xml.resource.org/public/rfc/bibxml/reference.RFC.5936.xml">
<!ENTITY rfc6347 SYSTEM
"http://xml.resource.org/public/rfc/bibxml/reference.RFC.6347.xml">
<!ENTITY rfc6973 SYSTEM "http://xml.resource.org/public/rfc/bibxml/reference.RFC.6973.xml">
<!ENTITY I-D.koch-perpass-dns-confidentiality SYSTEM
"http://xml.resource.org/public/rfc/bibxml3/reference.I-D.koch-perpass-dns-confidentiality.xml">
<!ENTITY I-D.vandergaast-edns-client-subnet SYSTEM
"http://xml.resource.org/public/rfc/bibxml3/reference.I-D.vandergaast-edns-client-subnet">
]>

<rfc docName="draft-bortzmeyer-dnsop-dns-privacy-00" category="info" ipr="trust200902">
<?rfc toc="yes"?>
<?rfc strict="yes"?> 
<front>
<title abbrev="DNS privacy">DNS privacy problem statement</title>
<author fullname="Stephane Bortzmeyer" initials="S." surname="Bortzmeyer">
<organization>AFNIC</organization>
<address><postal><street>Immeuble International</street><code>78181</code><city>Saint-Quentin-en-Yvelines</city><country>France</country></postal> <phone>+33 1 39 30 83 46</phone><email>bortzmeyer+ietf@nic.fr</email><uri>http://www.afnic.fr/</uri></address>
</author>
<date month="November" year="2013"/>
<abstract>
<t>This document describes the privacy issues associated with the use
of the
DNS by Internet users. It is intended to be mostly a problem statement and it does not
prescribe solutions (although <xref target="solutions"/> suggests some possible improvments).</t>
<t>Discussions of the document should take place on the dnsop
mailing list [dnsop]</t>
</abstract>
</front>

<middle>
<section title="Introduction">
<t>The Domain Name System is specified in <xref
target="RFC1034"/> and <xref target="RFC1035"/>. It is one of the
most important infrastructure components of the Internet and one of
the most often ignored or misunderstood. Almost every activity on the
Internet starts with a DNS query (and often several). Its use has many privacy
implications and we try to give here a comprehensive and accurate
list.</t>
<t>Let us start with a small reminder of the way the DNS works (with
some simplifications). A client, the stub resolver, issues a DNS query
to a server, the resolver (also called caching resolver or full resolver or recursive name server). For instance, the query is "What are the
AAAA records for www.example.com?". AAAA is the qtype (Query Type)
and www.example.com the qname (Query Name). To get the answer, the resolver
will query first the root nameservers, which will, most of the times,
send a referral. Here, the referral will be to .com nameservers. In
turn, they will send a referral to the example.com nameservers, which
will provide the answer. The root name servers, the name servers of
.com and those of example.com are called authoritative name servers. It is important, when analyzing the privacy
issues, to remember that the question asked to all these name servers
is always the original question, not a derived question. Unlike what
many "DNS for dummies" articles say, the question sent to the root
name servers is "What are the
AAAA records for www.example.com?", not "What are the name servers
of .com?". So, the DNS leaks more information than it should.</t>
<t>Because the DNS uses caching heavily, not all questions are sent to
the authoritative name servers. If the stub resolver, a few seconds
later, asks to the resolver "What are the SRV records of
_xmpp-server._tcp.example.com?", the resolver will remember that it
knows the name servers of example.com and will just query them,
bypassing the root and .com. Because there is typically no caching in
the stub resolver, the resolver, unlike the authoritative servers, sees everything.
</t>
<t>Almost all the DNS queries are today sent over UDP, and this has
practical consequences if someone thinks of encrypting this traffic
(some encryption solutions are
typically done for TCP, not UDP).</t>
<t>I should be noted to that DNS resolvers sometimes forward requests to
bigger machines, with a larger and more shared cache, the
forwarders. From the point of view of privacy, forwarders are like
resolvers, except that the caching in the resolver before them
decreases the amount of data they can see.</t>
<t>We will use here the terminology of <xref target="RFC6973"/>.</t>
</section>

<section title="Risks">

<t>This draft is limited to the study of privacy risks for the end-user (the one performing DNS
requests). Privacy risks for the holder of a zone (the risk that
someone gets the data) are discussed in <xref target="RFC5936"/> and
in <xref target="I-D.koch-perpass-dns-confidentiality"/>. Non-privacy
risks (such as cache poisoning) are out of scope.</t>

<section title="Data in the DNS request">
<t>The DNS request includes many fields but two of them seem specially
relevant for the privacy issues, the qname and the source IP
address. "source IP address" is used in a loose sense of "source IP address
+ may be source port", because the port is also in the request and can be used to sort out several users
sharing an IP address (CGN for instance).</t>
<t>The qname is the full name sent by the original user. It gives
information about what the user does ("What are the MX records of
example.net?" means he probably wants to send email to someone at
example.net, which may be a domain used by only a few persons and
therefore very revealing). Some qnames are more sensitive than
others. For instance, querying the A record of google-analytics.com
reveals very little (everybody visits Web sites which use Google
Analytics) but querying the A record of www.verybad.example where
verybad.example is the domain of an illegal or very offensive
organization may create more problems for the user. Another example is when
the qname embeds the software one uses. For instance, some
BitTorrent clients query a SRV record for _bittorrent-tracker._tcp.domain.example.</t>
<t>For the communication between the stub resolver and the resolver,
the source IP address is the one of the user's machine. Therefore, all
the issues and warnings about collection of IP addresses apply
here. For the communication between the resolver and the authoritative
name servers, the source IP address has a different meaning, it does not have the same status as the source
address in a HTTP connection. It is now the IP address of the resolver
which, in a way "hides" the real user. However, it does not always
work. Sometimes <xref
target="I-D.vandergaast-edns-client-subnet"/> is used. Sometimes the end user has a personal resolver on her
machine. In that case, the IP address is as sensitive as it is for HTTP.</t>
</section>

<section anchor="risks-on-wire" title="On the wire">
<t>DNS traffic can be seen by an eavesdropper like any other
traffic. It is typically not encrypted. (DNSSEC, specified in <xref
target="RFC4033"/> explicitely excludes confidentiality from its
goals.) So, if an initiator starts a HTTPS communication with a
recipient, while the HTTP traffic will be encrypted, the DNS exchange
prior to it will not be. When the other protocols will become more or
more privacy-aware and secured against surveillance, the DNS risks to
become "the weakest link" in privacy.</t>
<t>What also makes the DNS traffic different is that it may take a
different path than the communication between the initiator and the
recipient. For instance, an eavesdropper may be unable to tap the wire
between the initiator and the recipient but may have access to the
wire going to the resolver, or to the authoritative name servers.</t>
<t>The best place, from an eavesdropper's point of view, is clearly
between the stub resolvers and the resolvers, because he is not
limited by DNS caching.</t>
<t>The attack surface between the stub resolver and the rest of the world
can vary widely depending upon how the end user's computer is
configured. By order of increasing attack surface:</t>
<t>The resolver can be on the end user's computer. In (currently) a small number of cases,
individuals may choose to operate their own DNS resolver on their local
machine. In this case the attack surface for the stub resolver to caching
resolver connection is limited to that single machine.
</t>
<t>The resolver can be in the IAP (Internet Access Provider) premises.
For most residential users and potentially other
networks the typical case is for the end user's computer to be configured
(typically automatically through DHCP) with the addresses of the DNS
resolver at the IAP.  The attack surface for on-the-wire attacks is
therefore from the end user system across the local network and across the
IAP
network to the IAP's resolvers.</t>
<t>The resolver may also be at the local network edge. For many/most enterprise networks
and for some residential users the caching resolver may exist on a server
at the edge of the local network.  In this case the attack surface is the
local network.  Note that in large enterprise networks the DNS resolver
may not be located at the edge of the local network but rather at the edge
of the overall enterprise network. In this case the enterprise network
could be thought of as similar to the IAP network referenced above.</t>
<t>The resolver can be a public DNS service. Some end users may be configured to
use public DNS resolvers such as those operated by Google Public DNS or
OpenDNS. The end user may have configured their machine to use
these DNS resolvers themselves - or their IAP may choose to use the public
DNS resolvers rather than operating their own resolvers.  In this case the
attack surface is the entire public Internet between the end user's
connection and the public DNS service.</t>
</section>

<section title="In the servers">
<t>Using the terminology of <xref target="RFC6973"/>, the DNS servers
(resolvers and authoritative servers) are enablers: they facilitate communication between
an initiator and a recipient without being directly in the
communications path. As a result, they are often forgotten in risk
analysis. But, to quote again <xref target="RFC6973"/>, "Although [...] enablers may not generally
be considered as attackers, they may all pose privacy threats
(depending on the context) because they are able to observe, collect,
process, and transfer privacy-relevant data." In <xref
target="RFC6973"/> parlance, enablers become observers when they start
collecting data.</t>
<t>Many programs exist to collect and analyze DNS data at the servers. From the
"query log" of some programs like BIND, to tcpdump and more
sophisticated programs like PacketQ TODO reference and DNSmezzo TODO reference. The organization
managing the DNS server can use this data itself or it can be
part of a surveillance program like <xref target="prism">PRISM</xref> and
pass data to an outside attacker.</t>
<t>Sometimes, these data are kept for a long time and/or 
distributed to third parties, for research purposes [ditl], for
security analysis, or for surveillance tasks. Also, there are
observation points in the network which gather DNS data and then make
it accessible to third-parties for research or security purposes
("<xref target="passive-dns">passive DNS</xref>").</t>

<section title="In the resolvers">
<t>The resolvers see the entire traffic since there is typically no
caching before them. They are therefore well situated to observe the
traffic. To summarize: your resolver knows a lot about you. The resolver
of a large IAP, or a large public resolver can collect data from many
users. You may get an idea of the data collected by reading <eref
target="https://developers.google.com/speed/public-dns/privacy">the
privacy policy of a big public resolver</eref>. <!-- TODO published
policies of OpenDNS: nothing found on their Web site, only for the
Web, not for the DNS service, question sent, indirect reply received
TODO summarize --></t>
</section>

<section title="In the authoritative name servers">
<t>Unlike the resolvers, they are limited by caching. They see only a
part of the requests. For aggregated statistics ("what is the
percentage of LOC queries?"), it is sufficient but it may prevent an
observer to observe everything. Nevertheless, the authoritative name
servers sees a part of the traffic and this sample may be sufficient to
defeat some privacy expectations.</t>
<t>Also, the end user has typically some legal/contractual link with
the resolver (he has chosen the IAP, or he has chosen to use a given public
resolver) while he is often not even aware of the role of the
authoritative name servers and their observation abilities.</t>
<t>It is an interesting question whether the privacy issues are bigger
in the root or in a large TLD. The root sees the traffic for all the TLDs (and the huge
amount of traffic for non-existing TLD) but a large TLD has less caching
before it.</t>
<t>As noted before, using a local resolver or a resolver close to the
machine decreases the attack surface for an on-the-wire
eavesdropper. But it may decrease privacy against an observer located
on an authoritative name server since the authoritative name server
will see the IP address of the end client, and not the address of a
big resolver shared by many users. This is no longer true if <xref
target="I-D.vandergaast-edns-client-subnet"/> is used because, in this
case, the authoritative name server sees the original IP prefix or address (depending on the setup).</t>
<t>As of today, all the instances of one root name server, L-root,
receive together around 20 000 queries per second<!-- http://dns.icann.org/cgi-bin/dsc-grapher.pl?plot=bynode&server=L-root -->. While most of it is junk (errors on
the TLD name), it gives an idea of the amount of big data which pours
into name servers.</t>
<t>Many domains, including TLD, are partially hosted by third-party
servers, sometimes in a different country. The contracts between the
domain manager and these servers may or may not take privacy into
account. But it may be surprising for an end-user that requests to a
given ccTLD may go to servers managed by organisations outside of the country.</t>
</section>

<section title="Rogue servers">
<t>A rogue DHCP server can direct you to a rogue resolver. Most of the
times, it seems to be done to divert traffic, by providing lies for
some domain names. But it could be used just to
capture the traffic and gather information about you. Same thing for
malwares like DNSchanger<xref target="dnschanger"/> which changes the
resolver in the machine's configuration.</t>
</section>

</section>

</section>

<section title="Actual "attacks"">
<t>Many research papers about malware detection use DNS traffic to
detect "abnormal" behaviour that can be traced back to the activity of
malware on infected machines. Yes, this reasearch was done for the good but,
technically, it is a privacy attack and it demonstrates the power of
the observation of DNS traffic. See <xref target="dns-footprint"/>,
<xref target="dagon-malware"/> and <xref target="darkreading-dns"/>.</t>
</section>

<section title="Legalities">
<t>To our knowledge, there are no specific privacy laws for DNS
data. Interpreting general privacy laws like
[data-protection-directive] (European Union) in the context of DNS traffic data is not
an easy task and it seems there is no court precedent here.</t>
</section>

<section anchor="solutions" title="Possible technical solutions">

<t>We mention here only the solutions that could be deployed in the
current Internet. Disruptive solutions, like replacing the DNS with a
completely new resolution protocol, are interesting but are kept for a
future work. Remember that the focus of this document is on describing
the threats, not in detailing solutions. This section is therefore
non-normative and is NOT
a technical specification of solutions. For the same reason, there are
not yet actual recommendations in this document.</t>

<t>Raising seriously the bar against
the eavesdropper will require SEVERAL actions. Not one is decisive
by itself but, together, they can have an effect. The most important
suggested here are:
<list>
<t>qname minimization,</t>
<t>encryption of DNS traffic,</t>
<t>padding (sending random queries from time to time).</t>
</list>
</t>

<t>We detail some of these actions later, classified by the kind of
observer (on the wire, in a server, etc). Some actions will help
against several kinds of observers. For instance, padding, sending gratuitous queries from time to time (queries where
you're not interested in the replies, just to disturb the
analysis), is useful against all sorts of observers. It is a costly
technique, because it increases the traffic on the network but it
seriously blurs the picture for the observer.</t>

<section title="On the wire">
<section title="Reducing the attack surface">
<t>See <xref target="solutions-in-resolvers"/> since the
solution described there apply against on-the-wire eavesdropping as
well as against observation by the resolver.</t>
</section>
<section title="Encrypting the DNS traffic">
<t>To really defeat an eavesdropper, there is only one solution:
encryption. But, from the end user point of view, even if you check
that your communication between your stub resolver and the resolver is
encrypted, you have no way to ensure that the communication between
the resolver and the autoritative name servers will be. There are two
different cases, 
communication between the stub resolver and the resolver (no caching but only
two parties so solutions which rely on an agreement may work) and
communication between the resolver and the authoritative servers (less
data because of caching, but many
parties involved, so any solution has to scale well).
Encrypting the "last mile", between the user's stub resolver and the
resolver may be
sufficient since the biggest danger for privacy is between the stub resolver and
the resolver, because there is no caching involved there.</t>
<t>The only encryption mechanism available for DNS which is today an IETF
standard is IPsec in ESP mode. Its deployment in the wide Internet is
very limited, for reasons which are out of scope here. Still, it may be a solution for "the last mile" and, indeed,
many VPN solutions use it this way, encrypting the whole traffic,
including DNS to the safe resolver. In the IETF standards, a possible
alternative could be
DTLS <xref target="RFC6347"/>. It enjoyed very little actual
deployment and its interaction with the DNS has
never been considered, studied or of course implemented. There are
also non
standard encryption techniques like DNScrypt <xref target="dnscrypt"/> for the
stub resolver <-> resolver communication or
DNScurve <xref target="dnscurve"/> for the resolver <-> authoritative server
communication. It seems today that the possibility of massive encryption of
DNS traffic is very remote.</t>
<t>A last "pervasive encryption" solution for the DNS could be
"Confidential DNS" by W. Wijngaards which is not published yet but
seems promising.</t>
<t>Another solution would be to use more TCP for the queries, together
with TLS <xref target="RFC5246"/>. DNS can run over TCP and it
provides a good way to leverage the software and experience of the TLS
world. There have been discussions to use more TCP for the DNS, in
light of reflection attacks (based on the spoofing of the source IP
address, which is much more difficult with TCP). For instance, a stub
resolver could open a TCP connection with the resolver at startup and
keep it open to send queries and receive responses. The server would
of course be free to tear down these connections at will (when it is
under stress, for instance) and the client could reestablish them when necessary.
Remember that TLS sessions can survive
TCP connections so there is no need to restart the TLS negociation
each time. This DNS-over-TLS-over-TCP is already implemented in the
Unbound resolver. It is safe only if pipelining multiple questions over
the same channel. Name compression should also be disabled, or
<xref target="crime">CRIME-style</xref> attacks can apply.
</t>
<t>Encryption alone does not guarantee perfect privacy, because of the
available metadata. For instance, the size of questions and responses, even encrypted, provide hints about what queries have
been sent. (DNScrypt uses random-length padding, and a
64 bytes block size, to limit this risk, but this raises other issues,
for instance during amplification attacks. Other security protocols use similar techniques, for instance ESPv3.) Observing the periodicity of encrypted questions/responses also discloses the TTL, which is
yet another hint about the queries. Non-cached responses are
disclosing the RTT between the resolver and authoritative
servers. This is a very useful indication to guess where authoritative
servers are located. Web pages are made of many resources, leading to multiple requests, whose number and timing
fingerprint which web site is being browsed. So, observing encrypted
traffic is not enough to recover any plaintext queries, but is enough
to answer the question “is one of my employees browsing Facebook?”. Finally, attackers can
perform a denial-of-service attack on possible targets, check if this makes a difference on the
encrypted traffic they observe, and infer what a query was.
</t>  
</section>
</section>

<section title="In the servers">

<section anchor="solutions-in-resolvers" title="In the resolvers">
<t>It does not seem there is a possible solution against a leaky
resolver. A resolver has to see the entire DNS traffic in clear.</t>
<t>The best approach to limit the problem is to have local resolvers
whose caching will limit the leak. Local networks should have a local
caching resolver (even if it forwards the unanswered questions to a
forwarder) and individual laptops can have their very own resolver, too.</t>
<t>One mechanism to potentially mitigate on the wire attacks between stub
resolvers and caching resolvers is to determine if the network location of
the caching resolver can be moved closer to the end user's computer
(reducing the attack surface).  As
noted earlier in <xref target="risks-on-wire"/>, if an end user's computer is configured with
a caching resolver on the edge of the local network, an attacker would
need to gain access to that local network in order to successfully execute
an on the wire attack against the stub resolver.  On the other hand, if
the end user's computer is configured to use a public DNS service as the
caching resolver, the attacker needs to simply get in the network path
between the end user and the public DNS server and so there is a much
greater opportunity for a successful attack.  Configuring a caching
resolver closer to the end user can also reduce the possibility of on the wire
attacks.</t>
</section>

<section title="In the authoritative name servers">
<t>A possible solution would be to minimize the amount of data sent
from the resolver. When a resolver receives the query "What is the
AAAA record for www.example.com?", it sends to the root (assuming a
cold resolver, whose cache is empty) the very same question. Sending
"What are the NS records for .com?" would be sufficient (since
it will be the answer from the root anyway). To do so would be
compatible with the current DNS system and therefore could be
deployable, since it is an unilateral change to the resolvers.</t>
<t>To do so, the resolver needs to know the zone cut <xref
target="RFC2181"/>. There is not a zone cut at every label
boundary. If we take the name www.foo.bar.example, it is possible that
there is a zone cut between "foo" and "bar" but not between "bar" and
"example"<!-- A real example is www.economie.gouv.fr -->. So, assuming the resolver already knows
the name servers of .example, when it receives the query "What is the
AAAA record of www.foo.bar.example", it does not always know if the
request should be sent to the name servers of bar.example or to those
of example. <xref
target="RFC2181"/> suggests an algorithm to find the zone cut, so
resolvers may try it.</t>
<t>Note that DNSSEC-validating resolvers already have access to this information, since they
have to find the zone cut (the DNSKEY record set is just below, the DS
record set just above).</t>
<t>It can be noted that minimizing the amount of data sent also partially addresses the case of a wire sniffer.</t>
<t>One should note that the behaviour suggested here
(minimizing the amount of data sent in qnames) is NOT forbidden by the <xref
target="RFC1034"/> (section 5.3.3) or <xref target="RFC1035"/>
(section 7.2). Sending the full qname to the authoritative name server
is a tradition, not a protocol requirment.</t>
<t>Another note is that the answer to the
NS query, unlike the referral sent when the question is a full qname,
is in the Answer section, not in the Authoritative section. It has
probably no practical consequences.</t>
</section>

<section title="Rogue servers">
<t>Traditional security measures (do not let malware change
the system configuration) are of course a must. A protection against rogue servers announced
by DHCP could be to have a local resolver, and to always use it,
ignoring DHCP.</t>
</section>

</section>

</section>

<section title="Security considerations">
<t>Hey, man, the entire document is about security!</t>
</section>

<section title="Acknowledgments">
<t>Thanks to Nathalie Boulvard and to the CENTR members for the
original work which leaded to this draft. Thanks to Olaf Kolkman, Francis Dupont and Ondrej Sury for the
interesting discussions. Thanks to Mohsen Souissi for proofreading. Thanks to Dan York and Frank Denis for good written contributions.</t>
</section>

</middle>

<back>

<references title='Normative References'>
&rfc1034;
&rfc1035;
&rfc2119;
&rfc6973;
</references>

<references title='Informative References'>
&rfc2181;
&rfc4033;
&rfc5246;
&rfc5936;
&rfc6347;
&I-D.koch-perpass-dns-confidentiality;
&I-D.vandergaast-edns-client-subnet;

<reference anchor="dnsop">
<front>
<title>The dnsop mailing list</title>
<author fullname="IETF" surname="IETF"/>
<date month="October" year="2013"/>
<abstract>
<t>DNSOP is the IETF Working Group tasked with all the DNS operations issues <eref target="http://www.ietf.org/mail-archive/web/dnsop/"/></t>
</abstract>
</front>
</reference>

<reference anchor="dagon-malware">
<front>
<title>Corrupted DNS Resolution Paths: The Rise of a Malicious
Resolution Authority</title>
<author surname="Dagon" initials="D." fullname="David Dagon"/>
<date year="2007"/>
<abstract>
<t>Presented at the DNS-OARC meeting in Atlanta. <eref target="https://www.dns-oarc.net/files/workshop-2007/Dagon-Resolution-corruption.pdf"/></t>
</abstract>
</front>
</reference>

<reference anchor="dns-footprint">
<front>
<title>DNS footprint of malware</title>
<author fullname="Ed Stoner" surname="Stoner" initials="E."/>
<date day="13" month="October" year="2010"/>
<abstract>
<t>Finding Malicious Activity Using Network Flow Data. Presented at the DNS-OARC meeting in Denver. <eref target="https://www.dns-oarc.net/files/workshop-201010/OARC-ers-20101012.pdf"/></t>
</abstract>
</front>
</reference>

<reference anchor="darkreading-dns">
<front>
<title>Got Malware? Three Signs Revealed In DNS Traffic</title>
<author fullname="Robert Lemos" surname="Lemos" initials="R."/>
<date month="May" year="2013" day="3"/>
<abstract>
<t>Monitoring your network's requests for domain lookups can reveal
network problems and potential malware infections. <eref target="http://www.darkreading.com/monitoring/got-malware-three-signs-revealed-in-dns/240154181"/></t>
</abstract>
</front>
</reference>

<reference anchor="dnschanger">
<front>
<title>DNSchanger</title>
<author fullname="Wikipedia" surname="Wikipedia"/>
<date month="November" year="2011"/>
<abstract>
<t><eref target="http://en.wikipedia.org/wiki/DNSChanger"/></t>
</abstract>
</front>
</reference>

<reference anchor="dnscrypt">
<front>
<title>DNSCrypt</title>
<author fullname="Frank Denis" surname="Denis" initials="F."/>
<date/>
<abstract>
<t>A tool for securing communications between a client [stub resolver]
and a DNS resolver. <eref target="http://dnscrypt.org/"/></t>
</abstract>
</front>
</reference>

<reference anchor="dnscurve">
<front>
<title>DNScurve</title>
<author fullname="Dan Bernstein" surname="Bernstein" initials="D."/>
<date/>
<abstract>
<t>DNSCurve uses high-speed high-security elliptic-curve cryptography
and claims 
to "drastically improve every dimension of DNS security". <eref target="http://dnscurve.org/"/><!-- The text in
http://dnscurve.org/espionage.html mentions only wire sniffing and
copmpletey forgets PRISM-style attacks. --></t></abstract>
</front>
</reference>

<reference anchor="prism">
<front>
<title>PRISM</title>
<author fullname="National Security Agency" surname="NSA"/>
<date year="2007"/>
<abstract>
<t><eref target="http://en.wikipedia.org/wiki/PRISM_%28surveillance_program%29"/></t>
</abstract>
</front>
</reference>

<reference anchor="crime">
<front>
<title>The CRIME attack against TLS</title>
<author surname="Rizzo" initials="J." fullname="Juliano Rizzo"/>
<author surname="Dong" initials="T." fullname="Thai Duong"/>
<date year="2012"/>
<abstract>
<t><eref target="http://en.wikipedia.org/wiki/CRIME_(security_exploit)"/></t>
</abstract>
</front>
</reference>

<reference anchor="ditl">
<front>
<title>A Day in the Life of the Internet (DITL)</title>
<author fullname="CAIDA"/>
<date year="2002"/>
<abstract>
<t>CAIDA, ISC, DNS-OARC, and many partnering root nameserver operators
and other organizations to coordinate and conduct large-scale,
simultaneous traffic data collection events with the goal of capturing
datasets of strategic interest to researchers. Over the last several
years, we have come to refer to this project and related activities as
"A Day in the Life of the Internet" (DITL). <eref target="http://www.caida.org/projects/ditl/"/></t>
</abstract>
</front>
</reference>

<reference anchor="data-protection-directive">
<front>
<title>European directive 95/46/EC on the protection of individuals
with regard to the processing of personal data and on the free
movement of such data</title>
<author fullname="European Parliament"/>
<date day="23" month="November" year="1995"/>
<abstract>
<t><eref target="http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31995L0046:EN:HTML"/></t>
</abstract>
</front>
</reference>

<reference anchor="passive-dns">
<front>
<title>Passive DNS Replication</title>
<author fullname="Florian Weimer" initials="F." surname="Weimer"/>
<date month="April"  year="2005"/>
<abstract>
<t>FIRST 17 <eref target="http://www.enyo.de/fw/software/dnslogger/#2"/></t>
</abstract>
</front>
</reference>
</references>

</back>

</rfc>