Internet DRAFT - draft-grothoff-iesg-special-use-p2p-gns
draft-grothoff-iesg-special-use-p2p-gns
Internet Engineering Task Force C. Grothoff
Internet-Draft INRIA
Intended status: Informational M. Wachs
Expires: December 24, 2015 Technische Universitaet Muenchen
H. Wolf, Ed.
GNU consensus
J. Appelbaum
L. Ryge
Tor Project Inc.
June 30, 2015
Special-Use Domain Names of the GNU Name System
draft-grothoff-iesg-special-use-p2p-gns-00
Abstract
This document registers a set of Special-Use Domain Names for use
with Peer-to-Peer (P2P) systems, as per RFC6761.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Terminology and Conventions Used in This Document . . . . . . 3
4. Description of Special-Use Domains in P2P Networks . . . . . 4
4.1. The "GNU" Relative pTLD . . . . . . . . . . . . . . . . . 4
4.2. The "ZKEY" Compressed Public Key pTLD . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The GNU Name System (GNS) uses "GNU" and "ZKEY" to realize privacy-
enhanced, fully-decentralized and censorship-resistant naming.
In order to avoid interoperability issues with DNS as well as to
address security and privacy concerns, this document registers a set
of Special-Use Domain Names for use with P2P systems (pTLDs), as per
[RFC6761],: "GNU" and "ZKEY".
2. Applicability
[RFC6761] Section 3 states:
"[I]f a domain name has special properties that affect the way
hardware and software implementations handle the name, that apply
universally regardless of what network the implementation may be
connected to, then that domain name may be a candidate for having
the IETF declare it to be a Special-Use Domain Name and specify
what special treatment implementations should give to that name.
On the other hand, if declaring a given name to be special would
result in no change to any implementations, then that suggests
that the name may not be special in any material way, and it may
be more appropriate to use the existing DNS mechanisms [RFC1034]
to provide the desired delegation, data, or lack-of-data, for the
name in question. Where the desired behaviour can be achieved via
the existing domain name registration processes, that process
should be used. Reservation of a Special-Use Domain Name is not a
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mechanism for circumventing normal domain name registration
processes."
The set of Special-Use Domain Names for the GNU Name System (pTLDs)
reserved by this document meet this requirement, as they share the
following specificities:
o pTLDs are not manageable by some designated administration.
Instead, they are managed according to various alternate
strategies or combinations thereof, introduced in this document,
and their respective protocol specifications: automated
cryptographic assignment (".zkey"), or user-controled assignment
in a private scope (".gnu").
o The pTLDs do not depend on the DNS context for their resolution:
GNS resolution MAY involve the DNS server infrastructure, as it
returns DNS-compatible results; however, a specific P2P protocol
is used for regular name resolution, covered by its respective
protocol specification.
o GNS name resolution is typically integrated with existing software
libraries and APIs to extend regular DNS operation and enable more
secure name resolution. GNS implementations MUST intercept
queries for the respective pTLDs to ensure GNS names cannot leak
into the DNS from properly configured systems. Nevertheless, in
case GNS names do leak into the DNS, the default hierarchical DNS
response to any request to any pTLD MUST be NXDOMAIN.
o Finally, in order to facilitate the GNU Name System's vision of a
censorship-resistant, fully-decentralized name system, and provide
security and privacy features matching user expectations, this
document specifies desirable changes in existing DNS software and
DNS operations.
3. Terminology and Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The word "peer" is used in the meaning of a individual system on the
network.
The abbreviation "pTLD" is used in this document to mean a pseudo
Top-Level Domain, i.e., a Special-Use Domain Name per [RFC6761]
reserved to the GNU Name System in this document. A pTLD is
mentioned in capitals, and within double quotes to mark the
difference with a regular DNS gTLD.
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In this document, ".tld" (lowercase, with quotes) means: any domain
or hostname within the scope of a given pTLD, while .tld (lowercase,
without quotes) refers to an adjective form. For example, a
collection of ".gnu" peers in "GNU", but an .gnu URL. [TO REMOVE: in
the IANA Considerations section, we use the simple .tld format to
request TLD reservation for consistency with previous RFCs].
The word "NXDOMAIN" refers to an alternate expression for the "Name
Error" RCODE as described in section 4.1.1 of [RFC1035]. When
referring to "NXDOMAIN" and negative caching [RFC2308] response, this
document means an authoritative (AA=1) name error (RCODE=3) response
exclusively.
4. Description of Special-Use Domains in P2P Networks
4.1. The "GNU" Relative pTLD
"GNU" is used to specify that a domain name should be resolved using
GNS. The GNS resolution process is documented in [Wachs2014].
The "GNU" domain is special in the following ways:
1. Users can use these names as they would other domain names,
entering them anywhere that they would otherwise enter a
conventional DNS domain name.
Since there is no central authority responsible for assigning
.gnu names, and that specific domain is local to the local peer,
users need to be aware of that specificity.
Legacy applications MAY expect the DNS-to-GNS proxy to return DNS
compatible results for the resolution of .gnu domains.
2. Legacy application software does not need to recognize .gnu
domains as special, and may continue to use these names as they
would other domain names.
GNS-aware applications MAY also use GNS resolvers directly to
resolve .gnu domains (in particular, if they want access to GNS-
specific record types).
3. Name resolution APIs and libraries SHOULD either respond to
requests for .gnu names by resolving them via the GNS protocol,
or respond with NXDOMAIN.
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4. Caching DNS servers SHOULD recognize .gnu names as special and
SHOULD NOT attempt to look up NS records for them, or otherwise
query authoritative DNS servers in an attempt to resolve .gnu
names. Instead, caching DNS servers SHOULD generate immediate
negative responses for all such queries.
5. Authoritative DNS servers are not expected to treat .gnu domain
requests specially. In practice, they MUST answer with NXDOMAIN,
as "GNU" is not available via global DNS resolution, and not
doing so can put users' privacy at risk (see item 6).
6. DNS server operators SHOULD be aware that .gnu names are reserved
for use with GNS, and MUST NOT override their resolution (e.g.,
to redirect users to another service or error information).
7. DNS registries/registrars MUST NOT grant any request to register
.gnu names. This helps avoid conflicts [SAC45]. These names are
defined by the GNS protocol specification, and they fall outside
the set of names available for allocation by registries/
registrars.
4.2. The "ZKEY" Compressed Public Key pTLD
The "ZKEY" pTLD is used to signify that resolution of the given name
MUST be performed using a record signed by an authority that is in
possession of a particular public key. Names in "ZKEY" MUST end with
a domain which is the compressed point representation from [EdDSA] on
[Curve25519] of the public key of the authority, encoded using
Crockford's variant of base32hex [RFC4648] (with additionally 'U'
being considered equal to 'V') for easier optical character
recognition. A GNS resolver uses the key to locate a record signed
by the respective authority.
"ZKEY" provides a (reverse) mapping from globally unique hashes to
public key, therefore .zkey names are non-memorable, and are expected
to be hidden from the user [Wachs2014].
The "ZKEY" domain is special in the following ways:
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1. Users can use these names as they would other domain names,
entering them anywhere that they would otherwise enter a
conventional DNS domain name.
Since there is no central authority necessary or possible for
assigning .zkey names, and those names match cryptographic keys,
users need to be aware that they do not belong to regular DNS,
but are still global in their scope.
Legacy applications MAY expect the DNS-to-GNS proxy to return
DNS-compatible results for the resolution of .zkey domains.
2. Application software does not need to recognize .zkey domains as
special, and may continue to use these names as they would other
domain names.
GNS-aware applications MAY also use GNS resolvers directly to
resolve .zkey domains
3. Name resolution APIs and libraries SHOULD either respond to
requests for .zkey names by resolving them via the GNS protocol,
or respond with NXDOMAIN.
4. Caching DNS servers SHOULD recognize .zkey names as special and
SHOULD NOT attempt to look up NS records for them, or otherwise
query authoritative DNS servers in an attempt to resolve .zkey
names. Instead, caching DNS servers SHOULD generate immediate
negative responses for all such queries.
5. Authoritative DNS Servers are not expected to treat .zkey domain
requests specially. In practice, they MUST answer with NXDOMAIN,
as "ZKEY" is not available via global DNS resolution, and not
doing so MAY put users' privacy at risk (see item 6).
6. DNS server operators SHOULD be aware that .zkey names are
reserved for use with GNS, and MUST NOT override their resolution
(e.g., to redirect users to another service or error
information).
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7. DNS registries/registrars MUST NOT grant any request to register
.zkey names. This helps avoid conflicts [SAC45]. These names
are defined as described above, and they fall outside the set of
names available for allocation by registries/registrars.
5. Security Considerations
Specific software performs the resolution of names in the GNU Name
System; this resolution process happens outside of the scope of DNS.
Leakage of requests to such domains to the global operational DNS can
cause interception of traffic that might be misused to monitor,
censor, or abuse the user's trust, and lead to privacy issues with
potentially tragic consequences for the user.
This document reserves these Top-Level Domain names to minimize the
possibility of confusion, conflict, and especially privacy risks for
users.
In the introduction of this document, there's a requirement that DNS
operators do not override resolution of the GNS names. This is a
regulatory measure and cannot prevent such malicious abuse in
practice. Its purpose is to limit any information leak that would
result from incorrectly configured systems, and to avoid that
resolvers make unnecessary contact to the DNS Root Zone for such
domains. Verisign, Inc., as well as several Internet service
providers (ISPs) have notoriously abused their position to override
NXDOMAIN responses to their customers in the past
[SSAC-NXDOMAIN-Abuse]. For example, if a DNS operator would decide
to override NXDOMAIN and send advertising to leaked .zkey sites, the
information leak to the DNS would extend to the advertising server,
with unpredictable consequences. Thus, implementors should be aware
that any positive response coming from DNS must be considered with
extra care, as it suggests a leak to DNS has been made, contrary to
user's privacy expectations.
The reality of X.509 Certificate Authorities (CAs) creating
misleading certificates for these pTLDs due to ignorance stresses the
need to document their special use. X.509 Certificate Authorities
MAY create certificates for "ZKEY" given CSRs signed with the
respective private keys corresponding to the respective names.
Certificate Authorities MUST NOT create certificates for "GNU" Top-
Level domains. Nevertheless, clients SHOULD accept certificates for
"GNU" Top-Level domains as they may be created legitimately by local
proxies on the fly.
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Finally, legacy applications that do not explicitly support the pTLDs
significantly increase the risk of pTLD queries escaping to DNS, as
they are entirely dependent on the correct configuration on the
operating system.
6. IANA Considerations
The Internet Assigned Numbers Authority (IANA) reserved the following
entries in the Special-Use Domain Names registry [RFC6761]:
.gnu
.zkey
[TO REMOVE: the assignement URL is https://www.iana.org/assignments/
special-use-domain-names/ ]
7. Acknowledgements
The authors thank the I2P and Namecoin developers for their
constructive feedback, as well as Mark Nottingham for his proof-
reading and valuable feedback. The authors also thank the members of
DNSOP WG for their critiques and suggestions.
8. References
8.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS
NCACHE)", RFC 2308, March 1998.
[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, February 2013.
8.2. Informative References
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[Curve25519]
Bernstein, D., "Curve25519: new Diffie-Hellman speed
record", February 2006,
<http://cr.yp.to/ecdh/curve25519-20060209.pdf>.
[EdDSA] Bernstein, D., Duif, N., Lange, T., Schwabe, P., and Y.
Yang, "High-speed, high-security signatures", September
2011, <http://ed25519.cr.yp.to/ed25519-20110926.pdf>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
[SAC45] ICANN Security and Stability Advisory Committee, "Invalid
Top Level Domain Queries at the Root Level of the Domain
Name System", November 2010,
<http://www.icann.org/en/groups/ssac/documents/
sac-045-en.pdf>.
[SSAC-NXDOMAIN-Abuse]
ICANN Security and Stability Advisory Committee,
"Redirection in the COM and NET Domains", July 2004,
<http://www.icann.org/committees/security/
ssac-report-09jul04.pdf>.
[Wachs2014]
Wachs, M., Schanzenbach, M., and C. Grothoff, "A
Censorship-Resistant, Privacy-Enhancing and Fully
Decentralized Name System", October 2014,
<https://gnunet.org/gns-paper>.
Authors' Addresses
Christian Grothoff
INRIA
Equipe Decentralisee
INRIA Rennes Bretagne Atlantique
263 avenue du General Leclerc
Campus Universitaire de Beaulieu
Rennes, Bretagne F-35042
FR
Email: christian@grothoff.org
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Matthias Wachs
Technische Universitaet Muenchen
Free Secure Network Systems Group
Lehrstuhl fuer Netzarchitekturen und Netzdienste
Boltzmannstrasse 3
Technische Universitaet Muenchen
Garching bei Muenchen, Bayern D-85748
DE
Email: wachs@net.in.tum.de
Hellekin O. Wolf (editor)
GNU consensus
Email: hellekin@gnu.org
Jacob Appelbaum
Tor Project Inc.
Email: jacob@appelbaum.net
Leif Ryge
Tor Project Inc.
Email: leif@synthesize.us
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