The GNU Name System
draft-schanzen-gns-18
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 9498.
|
|
|---|---|---|---|
| Authors | Martin Schanzenbach , Christian Grothoff , Bernd Fix | ||
| Last updated | 2022-06-17 | ||
| RFC stream | Independent Submission | ||
| Formats | |||
| Reviews | |||
| IETF conflict review | conflict-review-schanzen-gns, conflict-review-schanzen-gns, conflict-review-schanzen-gns, conflict-review-schanzen-gns, conflict-review-schanzen-gns, conflict-review-schanzen-gns, conflict-review-schanzen-gns | ||
| Stream | ISE state | In IESG Review | |
| Consensus boilerplate | Unknown | ||
| Document shepherd | Eliot Lear | ||
| Shepherd write-up | Show Last changed 2022-05-07 | ||
| IESG | IESG state | Became RFC 9498 (Informational) | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | rfc-ise@rfc-editor.org | ||
| IANA | IANA review state | Version Changed - Review Needed |
draft-schanzen-gns-18
Independent Stream M. Schanzenbach
Internet-Draft Fraunhofer AISEC
Intended status: Informational C. Grothoff
Expires: 19 December 2022 Berner Fachhochschule
B. Fix
GNUnet e.V.
17 June 2022
The GNU Name System
draft-schanzen-gns-18
Abstract
This document contains the GNU Name System (GNS) technical
specification. GNS is a decentralized and censorship-resistant name
system that provides a privacy-enhancing alternative to the Domain
Name System (DNS).
This document defines the normative wire format of resource records,
resolution processes, cryptographic routines and security
considerations for use by implementers.
This specification was developed outside the IETF and does not have
IETF consensus. It is published here to inform readers about the
function of GNS, guide future GNS implementations, and ensure
interoperability among implementations including with the pre-
existing GNUnet implementation.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 19 December 2022.
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Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1. Zone Top-Level Domain . . . . . . . . . . . . . . . . . . 11
4.2. Zone Revocation . . . . . . . . . . . . . . . . . . . . . 12
5. Resource Records . . . . . . . . . . . . . . . . . . . . . . 16
5.1. Zone Delegation Records . . . . . . . . . . . . . . . . . 18
5.1.1. PKEY . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1.2. EDKEY . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2. Redirection Records . . . . . . . . . . . . . . . . . . . 26
5.2.1. REDIRECT . . . . . . . . . . . . . . . . . . . . . . 26
5.2.2. GNS2DNS . . . . . . . . . . . . . . . . . . . . . . . 26
5.3. Auxiliary Records . . . . . . . . . . . . . . . . . . . . 27
5.3.1. LEHO . . . . . . . . . . . . . . . . . . . . . . . . 28
5.3.2. NICK . . . . . . . . . . . . . . . . . . . . . . . . 28
5.3.3. BOX . . . . . . . . . . . . . . . . . . . . . . . . . 29
6. Record Encoding . . . . . . . . . . . . . . . . . . . . . . . 30
6.1. The Storage Key . . . . . . . . . . . . . . . . . . . . . 32
6.2. The Records Block . . . . . . . . . . . . . . . . . . . . 33
7. Name Resolution . . . . . . . . . . . . . . . . . . . . . . . 36
7.1. Start Zones . . . . . . . . . . . . . . . . . . . . . . . 37
7.2. Recursion . . . . . . . . . . . . . . . . . . . . . . . . 38
7.3. Record Processing . . . . . . . . . . . . . . . . . . . . 38
7.3.1. REDIRECT . . . . . . . . . . . . . . . . . . . . . . 39
7.3.2. GNS2DNS . . . . . . . . . . . . . . . . . . . . . . . 40
7.3.3. BOX . . . . . . . . . . . . . . . . . . . . . . . . . 41
7.3.4. Zone Delegation Records . . . . . . . . . . . . . . . 41
7.3.5. NICK . . . . . . . . . . . . . . . . . . . . . . . . 42
8. Internationalization and Character Encoding . . . . . . . . . 43
9. Security and Privacy Considerations . . . . . . . . . . . . . 43
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9.1. Availability . . . . . . . . . . . . . . . . . . . . . . 43
9.2. Agility . . . . . . . . . . . . . . . . . . . . . . . . . 43
9.3. Cryptography . . . . . . . . . . . . . . . . . . . . . . 44
9.4. Abuse Mitigation . . . . . . . . . . . . . . . . . . . . 45
9.5. Zone Management . . . . . . . . . . . . . . . . . . . . . 45
9.6. DHTs as Storage . . . . . . . . . . . . . . . . . . . . . 46
9.7. Revocations . . . . . . . . . . . . . . . . . . . . . . . 46
9.8. Zone Privacy . . . . . . . . . . . . . . . . . . . . . . 47
9.9. Namespace Ambiguity . . . . . . . . . . . . . . . . . . . 47
10. GANA Considerations . . . . . . . . . . . . . . . . . . . . . 48
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49
12. Implementation and Deployment Status . . . . . . . . . . . . 49
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 50
14. Normative References . . . . . . . . . . . . . . . . . . . . 50
15. Informative References . . . . . . . . . . . . . . . . . . . 53
Appendix A. Usage and Migration . . . . . . . . . . . . . . . . 54
A.1. Zone Dissemination . . . . . . . . . . . . . . . . . . . 55
A.2. Start Zone Configuration . . . . . . . . . . . . . . . . 55
A.3. Globally Unique Names and the Web . . . . . . . . . . . . 56
A.4. Migration Paths . . . . . . . . . . . . . . . . . . . . . 57
Appendix B. Example flows . . . . . . . . . . . . . . . . . . . 58
B.1. AAAA Example Resolution . . . . . . . . . . . . . . . . . 58
B.2. REDIRECT Example Resolution . . . . . . . . . . . . . . . 59
B.3. GNS2DNS Example Resolution . . . . . . . . . . . . . . . 61
Appendix C. Base32GNS . . . . . . . . . . . . . . . . . . . . . 62
Appendix D. Test Vectors . . . . . . . . . . . . . . . . . . . . 63
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 76
1. Introduction
The Domain Name System (DNS) [RFC1035] is a unique distributed
database and a vital service for most Internet applications. While
DNS is distributed, in practice it relies on centralized, trusted
registrars to provide globally unique names. As the awareness of the
central role DNS plays on the Internet rises, various institutions
are using their power (including legal means) to engage in attacks on
the DNS, thus threatening the global availability and integrity of
information on the Internet.
DNS was not designed with security in mind. This makes it very
vulnerable, especially to attackers that have the technical
capabilities of an entire nation state at their disposal. While a
wider discussion of this issue is out of scope for this document,
analyses and investigations can be found in recent academic research
works including [SecureNS].
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This specification describes a censorship-resistant, privacy-
preserving and decentralized name system: The GNU Name System (GNS)
[GNS]. It is designed to provide a secure, privacy-enhancing
alternative to DNS, especially when censorship or manipulation is
encountered. In particular, it directly addresses concerns in DNS
with respect to "Query Privacy", the "Single Hierarchy with a
Centrally Controlled Root" and "Distribution and Management of Root
Servers" as raised in [RFC8324]. GNS can bind names to any kind of
cryptographically secured token, enabling it to double in some
respects as an alternative to some of today's Public Key
Infrastructures, in particular X.509 for the Web.
The design of GNS incorporates the capability to integrate and
coexist with DNS. GNS is based on the principle of a petname system
where users can assign names to zones. It builds on ideas from the
Simple Distributed Security Infrastructure [SDSI], addressing a
central issue with the decentralized mapping of secure identifiers to
memorable names: namely the impossibility of providing a global,
secure and memorable mapping without a trusted authority. GNS uses
the transitivity in the SDSI design to replace the trusted root with
secure delegation of authority thus making petnames useful to other
users while operating under a very strong adversary model.
This is an important distinguishing factor from the Domain Name
System where root zone governance is centralized at the Internet
Corporation for Assigned Names and Numbers (ICANN). In DNS
terminology, GNS roughly follows the idea of a local root zone
deployment (see [RFC8806]), with the difference that it is not
expected that all deployments use the same root zone, and that users
can easily delegate control of arbitrary domain names to arbitrary
zones.
This document defines the normative wire format of resource records,
resolution processes, cryptographic routines and security
considerations for use by implementers.
This specification was developed outside the IETF and does not have
IETF consensus. It is published here to guide implementation of GNS
and to ensure interoperability among implementations.
1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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2. Terminology
Apex Label This type of label is used to publish resource records in
a zone that can be resolved without providing a specific label.
It is the GNS method to provide what is the "zone apex" in DNS
[RFC4033]. The apex label is represented using the character
U+0040 ("@" without the quotes).
Application A component which uses a GNS implementation to resolve
names into records and processes its contents.
Blinded Zone Key The key derived from a zone key and a label. The
zone key and the blinded zone key are unlinkable without knowledge
of the label.
Extension Label The primary use for the extension label is in
redirections where the redirection target is defined relative to
the authoritative zone of the redirection record (Section 5.2).
The extension label is represented using the character U+002B ("+"
without the quotes).
Label Separator Labels in a name are separated using the label
separator U+002E ("." without the quotes). In GNS, with the
exceptions of zone Top-Level Domains (see below) and boxed records
(see Section 5.3.3), every separator label in a name delegates to
another zone.
Label A GNS label is a label as defined in [RFC8499]. Labels are
UTF-8 strings in Unicode Normalization Form C (NFC)
[Unicode-UAX15]. The apex label, label separator and the
extension label have special purposes in the resolution protocol
which are defined in the rest of the document. Zone
administrators MAY disallow certain labels that might be easily
confused with other labels through registration policies (see also
Section 9.4).
Name A name in GNS is a domain name as defined in [RFC8499] as an
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ordered list of labels. Names are UTF-8 [RFC3629] strings
consisting of the list of labels concatenated with a label
separator. Names are resolved starting from the rightmost label.
GNS does not impose length restrictions on names or labels.
However, applications MAY ensure that name and label lengths are
compatible with DNS and in particular IDNA [RFC5890]. In the
spirit of [RFC5895], applications MAY preprocess names and labels
to ensure compatibility with DNS or support specific user
expectations, for example according to [Unicode-UTS46]. A GNS
name may be indistinguishable from a DNS name and care must be
taken by applications and implementors when handling GNS names
(see Section 9.9).
Resolver The component of a GNS implementation which provides the
recursive name resolution logic defined in Section 7.
Resource Record A GNS resource record is the information associated
with a label in a GNS zone. A GNS resource record contains
information as defined by its resource record type.
Start Zone In order to resolve any given GNS name an initial start
zone must be determined for this name. The start zone can be
explicitly defined through a zTLD. Otherwise, it is determined
through a local suffix-to-zone mapping (see Section 7.1).
Top-Level Domain The rightmost part of a GNS name is a GNS Top-Level
Domain (TLD). A GNS TLD can consist of one or more labels.
Unlike DNS Top-Level Domains (defined in [RFC8499]), GNS does not
expect all users to use the same global root zone. Instead, with
the exception of Zone Top-Level Domains (see below), GNS TLDs are
typically part of the configuration of the local resolver (see
Section 7.1), and might thus not be globally unique.
Zone A GNS zone contains authoritative information (resource
records). A zone is uniquely identified by its zone key. Unlike
DNS zones, a GNS zone does not need to have a SOA record under the
apex label.
Zone Key A key which uniquely identifies a zone. It is usually a
public key of an asymmetric key pair.
Zone Key Derivation Function The zone key derivation function (ZKDF)
blinds a zone key using a label.
Zone Master The component of a GNS implementation which provides
local zone management and publication as defined in Section 6.
Zone Owner The holder of the secret (typically a private key) that
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(together with a label and a value to sign) allows the creation of
zone signatures that can be validated against the respective
blinded zone key.
Zone Top-Level Domain A GNS Zone Top-Level Domain (zTLD) is a
sequence of GNS labels at the end of a GNS name which encodes a
zone type and zone key of a zone. Due to the statistical
uniqueness of zone keys, zTLDs are also globally unique. A zTLD
label sequence can only be distinguished from ordinary TLD label
sequences by attempting to decode the labels into a zone type and
zone key.
Zone Type The type of a GNS zone determines the cipher system and
binary encoding format of the zone key, blinded zone keys, and
signatures.
3. Overview
GNS exhibits the three properties of a petname system:
1. It provides global names through the concept of zone top-level
domains (zTLDs). As zones can be uniquely identified by their
zone key and are statistically unqiue, GNS names with a zTLD
suffix are also globally unique.
2. It provides memorable or "human-readable" names by enabling users
to configure local mappings from nicknames to zones. Zone owners
can publish their mappings in order to enable namespace
delegation and facilitate resolution of memorable names.
3. It provides secure mapping from names to records as zone contents
are signed using blinded private keys and encrypted using derived
secret keys.
In GNS, any user can create and manage one or more zones (Section 4)
as part of a zone master implementation. The zone type determines
the respective set of cryptographic operations and the wire formats
for encrypted data, public keys and signatures. A zone can be
populated with mappings from labels to resource records by its owner
(Section 5). A label can be mapped to a delegation record which
results in the corresponding subdomain being delegated to another
zone. Circular delegations are explicitly allowed, including
delegating a subdomain to its immediate parent zone. In order to
support (legacy) applications as well as to facilitate the use of
petnames, GNS defines auxiliary record types in addition to
supporting existing DNS records.
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Zone contents are encrypted and signed before being published in a
key-value storage (Section 6) as illustrated in Figure 1. In this
process, unique zone identification is hidden from the network
through the use of key blinding. Key blinding allows the creation of
signatures for zone contents using a blinded public/private key pair.
This blinding is realized using a deterministic key derivation from
the original zone key and corresponding private key using record
label values as blinding factors. Specifically, the zone owner can
derive blinded private keys for each record set published under a
label, and a resolver can derive the corresponding blinded public
keys. It is expected that GNS implementations use distributed or
decentralized storages such as distributed hash tables (DHT) in order
to facilitate availability within a network without the need for
dedicated infrastructure. Specification of such a distributed or
decentralized storage is out of scope of this document, but possible
existing implementations include those based on [RFC7363], [Kademlia]
or [R5N].
Local Host | Remote | Remote Host
| Storage |
| |
| +---------+ |
| / /| |
Publish | +---------+ | | Publish
+---------+ Records | | | | | Records +---------+
| Zone |----------|->| Record | |<-|----------| Zone |
| Master | | | Storage | | | | Master |
+---------+ | | |/ | +---------+
A | +---------+ | A
| | | |
+---------+ | | +---------+
/ | /| | | / | /|
+---------+ | | | +---------+ |
| | | | | | | |
| Local | | | | | Local | |
| Zones | | | | | Zones | |
| |/ | | | |/
+---------+ | | +---------+
Figure 1: An example diagram of two hosts publishing GNS zones.
Applications use the resolver to lookup GNS names. Starting from a
configurable start zone, names are resolved by following zone
delegations recursively as illustrated in Figure 2. For each label
in a name, the recursive GNS resolver fetches the respective record
from the storage layer (Section 7). Without knowledge of the label
values and the zone keys, the different derived keys are unlinkable
both to the original zone key and to each other. This prevents zone
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enumeration (except via impractical online brute force attacks) and
requires knowledge of both the zone key and the label to confirm
affiliation of a query or the corresponding encrypted record set with
a specific zone. At the same time, the blinded zone key provides
resolvers with the ability to verify the integrity of the published
information without disclosing the originating zone.
Local Host | Remote
| Storage
|
| +---------+
| / /|
| +---------+ |
+-----------+ Name +----------+ Recursive | | | |
| | Lookup | | Resolution | | Record | |
|Application|----------| Resolver |-------------|->| Storage | |
| |<---------| |<------------|--| |/
+-----------+ Results +----------+ Intermediate| +---------+
A Results |
| |
+---------+ |
/ | /| |
+---------+ | |
| | | |
| Start | | |
| Zones | | |
| |/ |
+---------+ |
Figure 2: High-level view of the GNS resolution process.
In the remainder of this document, the "implementer" refers to the
developer building a GNS implementation including the resolver, zone
master, and supporting configuration such as start zones
(Section 7.1).
4. Zones
A zone master implementation SHOULD enable the zone owners to create
and manage zones. If this functionality is not implemented, names
can still be resolved if zone keys for the initial step in the name
resolution are available (see Section 7).
A zone in GNS is uniquely identified by its zone type and zone key.
Each zone can be represented by a Zone Top-Level Domain (zTLD)
string. A zone type (ztype) is a unique 32-bit number. This number
corresponds to a resource record type number identifying a delegation
record type in the GNUnet Assigned Numbers Authority [GANA]. The
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ztype is a unique identifier for the set cryptographic functions of
the zone and the format of the delegation record type. Any ztype
MUST define the following set of cryptographic functions:
KeyGen() -> d, zk is a function to generate a new private key d and
the corresponding public zone key zk.
ZKDF(zk,label) -> zk' is a zone key derivation function which blinds
a zone key zk using a label. zk and zk' must be unlinkable.
Furthermore, blinding zk with different values for the label must
result in different, unlinkable zk' values.
S-Encrypt(zk,label,expiration,message) -> ciphertext is a symmetric
encryption function which encrypts the record data based on key
material derived from the zone key, a label, and an expiration
timestamp. In order to leverage performance-enhancing caching
features of certain underlying storages, in particular DHTs, a
deterministic encryption scheme is recommended.
S-Decrypt(zk,label,expiration,ciphertext) -> message is a symmetric
decryption function which decrypts the encrypted record data based
on key material derived from the zone key, a label, and an
expiration timestamp.
Sign(d,message) -> signature is a function to sign a message using
the private key d, yielding an unforgeable cryptographic
signature. In order to leverage performance-enhancing caching
features of certain underlying storages, in particular DHTs, a
deterministic signature scheme is recommended.
Verify(zk,message,signature) -> boolean is a function to verify the
signature was created using the private key d corresponding to the
zone key zk where d,zk := Keygen(). The function returns a
boolean value of "TRUE" if the signature is valid, and otherwise
"FALSE".
SignDerived(d,label,message) -> signature is a function to sign a
message (typically encrypted record data) that can be verified
using the derived zone key zk' := ZKDF(zk,label). In order to
leverage performance-enhancing caching features of certain
underlying storages, in particular DHTs, a deterministic signature
scheme is recommended.
VerifyDerived(zk,label,message,signature) -> boolean is function to
verify the signature using the derived zone key zk' :=
ZKDF(zk,label). The function returns a boolean value of "TRUE" if
the signature is valid, and otherwise "FALSE".
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The cryptographic functions of the default ztypes are specified with
their corresponding delegation records in Section 5.1. In order to
support cryptographic agility, additional ztypes MAY be defined in
the future which replace or update the default ztypes defined in this
document. All ztypes MUST be registered as dedicated zone delegation
record types in the GNU Name System Record Types registry (see
Section 10). When defining new record types the cryptographic
security considerations of this document apply, in particular
Section 9.3.
4.1. Zone Top-Level Domain
The zTLD is the Zone Top-Level Domain. It is a string which encodes
the zone type and zone key into a domain name. The zTLD is used as a
globally unique reference to a specific zone in the process of name
resolution. It is created by encoding a binary concatenation of the
zone type and zone key (see Figure 3). The used encoding is a
variation of the Crockford Base32 encoding [CrockfordB32] called
Base32GNS. The encoding and decoding symbols for Base32GNS including
this modification are defined in the table found in Figure 29. The
functions for encoding and decoding based on this table are called
Base32GNS-Encode and Base32GNS-Decode, respectively.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| ZONE TYPE | ZONE KEY /
+-----+-----+-----+-----+ /
/ /
/ /
Figure 3: The decoded binary representation of the zTLD
Consequently, a zTLD is encoded and decoded as follows:
zTLD := Base32GNS-Encode(ztype||zkey)
ztype||zkey := Base32GNS-Decode(zTLD)
where "||" is the concatenation operator.
The zTLD can be used as-is as a rightmost label in a GNS name. If an
application wants to ensure DNS compatibility of the name, it MAY
also represent the zTLD as follows: If the zTLD is less than or equal
to 63 characters, it can be used as a zTLD as-is. If the zTLD is
longer than 63 characters, the zTLD is divided into smaller labels
separated by the label separator. Here, the most significant bytes
of the "ztype||zkey" concatenation must be contained in the rightmost
label of the resulting string and the least significant bytes in the
leftmost label of the resulting string. This allows the resolver to
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determine the ztype and zTLD length from the rightmost label and to
subsequently determine how many labels the zTLD should span. A GNS
implementation MUST support the division of zTLDs in DNS compatible
label lengths. For example, assuming a zTLD of 130 characters, the
division is:
zTLD[126..129].zTLD[63..125].zTLD[0..62]
4.2. Zone Revocation
In order to revoke a zone key, a signed revocation message MUST be
published. This message MUST be signed using the private key. The
revocation message is broadcast to the network. The specification of
the broadcast mechanism is out of scope for this document. A
possible broadcast mechanism for efficient flooding in a distributed
network is implemented in [GNUnet]. Alternatively, revocation
messages could also be distributed via a distributed ledger or a
trusted central server. To prevent flooding attacks, the revocation
message MUST contain a proof of work (PoW). The revocation message
including the PoW MAY be calculated ahead of time to support timely
revocation.
For all occurrences below, "Argon2id" is the Password-based Key
Derivation Function as defined in [RFC9106]. For the PoW
calculations the algorithm is instantiated with the following
parameters:
S The salt. Fixed 16-byte string: "GnsRevocationPow".
t Number of iterations: 3
m Memory size in KiB: 1024
T Output length of hash in bytes: 64
p Parallelization parameter: 1
v Algorithm version: 0x13
y Algorithm type (Argon2id): 2
X Unused
K Unused
Figure 4 illustrates the format of the data "P" on which the PoW is
calculated.
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0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| POW |
+-----------------------------------------------+
| TIMESTAMP |
+-----------------------------------------------+
| ZONE TYPE | ZONE KEY |
+-----+-----+-----+-----+ |
/ /
/ /
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 4: The Format of the PoW Data.
POW A 64-bit value that is a solution to the PoW. In network byte
order.
TIMESTAMP denotes the absolute 64-bit date when the revocation was
computed. In microseconds since midnight (0 hour), January 1,
1970 UTC in network byte order.
ZONE TYPE is the 32-bit zone type.
ZONE KEY is the 256-bit public key zk of the zone which is being
revoked. The wire format of this value is defined by the ZONE
TYPE.
Usually, PoW schemes require to find one POW value such that a
specific number of leading zeroes are found in the hash result. This
number is then referred to as the difficulty of the PoW. In order to
reduce the variance in time it takes to calculate the PoW, a valid
GNS revocation requires that a number Z different PoWs must be found
that on average have D leading zeroes.
The resulting proofs are ready for dissemination. The concrete
dissemination and publication methods are out of scope of this
document. Given an average difficulty of D, the proofs have an
expiration time of EPOCH. With each additional bit difficulty, the
lifetime of the proof is prolonged for another EPOCH. Consequently,
by calculating a more difficult PoW, the lifetime of the proof can be
increased on demand by the zone owner.
The parameters are defined as follows:
Z The number of PoWs that are required. Its value is fixed at 32.
D The lower limit of the average difficulty. Its value is fixed at
22.
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EPOCH A single epoch. Its value is fixed at 365 days in
microseconds.
The revocation message wire format is illustrated in Figure 5.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| TIMESTAMP |
+-----+-----+-----+-----+-----+-----+-----+-----+
| TTL |
+-----+-----+-----+-----+-----+-----+-----+-----+
| POW_0 |
+-----+-----+-----+-----+-----+-----+-----+-----+
| ... |
+-----+-----+-----+-----+-----+-----+-----+-----+
| POW_Z-1 |
+-----------------------------------------------+
| ZONE TYPE | ZONE KEY |
+-----+-----+-----+-----+ |
/ /
/ /
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIGNATURE |
/ /
/ /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 5: The Revocation Message Wire Format.
TIMESTAMP denotes the absolute 64-bit date when the revocation was
computed. In microseconds since midnight (0 hour), January 1,
1970 UTC in network byte order. This is the same value as the
time stamp used in the individual PoW calculations.
TTL denotes the relative 64-bit time to live of the record in
microseconds in network byte order. The field SHOULD be set to
EPOCH * 1.1. Given an average number of leading zeros D', then
the field value MAY be increased up to (D'-D+1) * EPOCH * 1.1.
Validators MAY reject messages with lower or higher values when
received. The EPOCH is extended by 10% in order to deal with
unsynchronized clocks.
POW_i The values calculated as part of the PoW, in network byte
order. Each POW_i MUST be unique in the set of POW values. To
facilitate fast verification of uniqueness, the POW values must be
given in strictly monotonically increasing order in the message.
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ZONE TYPE The 32-bit zone type corresponding to the zone key.
ZONE KEY is the public key zk of the zone which is being revoked and
the key to be used to verify SIGNATURE.
SIGNATURE A signature over a time stamp and the zone zk of the zone
which is revoked and corresponds to the key used in the PoW. The
signature is created using the Sign() function of the cryptosystem
of the zone and the private key (see Section 4).
The signature over the public key covers a 32-bit header prefixed to
the time stamp and public key fields. The header includes the key
length and signature purpose. The wire format is illustrated in
Figure 6.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIZE | PURPOSE (0x03) |
+-----+-----+-----+-----+-----+-----+-----+-----+
| TIMESTAMP |
+-----+-----+-----+-----+-----+-----+-----+-----+
| ZONE TYPE | ZONE KEY |
+-----+-----+-----+-----+ |
/ /
/ /
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 6: The Wire Format of the Revocation Data for Signing.
SIZE A 32-bit value containing the length of the signed data in
bytes in network byte order.
PURPOSE A 32-bit signature purpose flag. The value of this field
MUST be 3. The value is encoded in network byte order. It
defines the context in which the signature is created so that it
cannot be reused in other parts of the protocol including possible
future extensions. The value of this field corresponds to an
entry in the GANA "GNUnet Signature Purpose" registry Section 10.
TIMESTAMP Field as defined in the revocation message above.
ZONE TYPE Field as defined in the revocation message above.
ZONE KEY Field as defined in the revocation message above.
In order to validate a revocation the following steps MUST be taken:
1. The signature MUST be verified against the zone key.
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2. The set of POW values MUST NOT contain duplicates which MUST be
checked by verifying that the values are strictly monotonically
increasing.
3. The average number of leading zeroes D' resulting from the
provided POW values MUST be greater than or equal to D.
Implementers MUST NOT use an integer data type to calculate or
represent D'.
The TTL field in the revocation message is informational. A
revocation MAY be discarded without checking the POW values or the
signature if the TTL (in combination with TIMESTAMP) indicates that
the revocation has already expired. The actual validity period of
the revocation MUST be determined by examining the leading zeroes in
the POW values.
The validity period of the revocation is calculated as (D'-D+1) *
EPOCH * 1.1. The EPOCH is extended by 10% in order to deal with
unsynchronized clocks. The validity period added on top of the
TIMESTAMP yields the expiration date. If the current time is after
the expiration date, the revocation is considered stale.
Verified revocations MUST be stored locally. The implementation MAY
discard stale revocations and evict then from the local store at any
time.
Implementations MUST broadcast received revocations if they are valid
and not stale. Should the calculated validity period differ from the
TTL field value, the calculated value MUST be used as TTL field value
when forwarding the revocation message. Systems might disagree on
the current time, so implementations MAY use stale but otherwise
valid revocations but SHOULD NOT broadcast them. Forwarded stale
revocations MAY be discarded.
Any locally stored revocation MUST be considered during delegation
record processing (Section 7.3.4).
5. Resource Records
A GNS implementation SHOULD provide a mechanism to create and manage
local zones as well as a persistence mechanism such as a database for
resource records. A new local zone is established by selecting a
zone type and creating a zone key pair. If this mechanism is not
implemented, no zones can be published in the storage (Section 6) and
name resolution is limited to non-local start zones (Section 7.1).
A GNS resource record holds the data of a specific record in a zone.
The resource record format is defined in Figure 7.
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0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| EXPIRATION |
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIZE | FLAGS | TYPE |
+-----+-----+-----+-----+-----+-----+-----+-----+
| DATA /
/ /
/ /
Figure 7: The Resource Record Wire Format.
EXPIRATION denotes the absolute 64-bit expiration date of the
record. In microseconds since midnight (0 hour), January 1, 1970
UTC in network byte order.
SIZE denotes the 16-bit size of the DATA field in bytes and in
network byte order.
FLAGS is a 16-bit resource record flags field (see below).
TYPE is the 32-bit resource record type. This type can be one of
the GNS resource records as defined in Section 5 or a DNS record
type as defined in [RFC1035] or any of the complementary
standardized DNS resource record types. This value must be stored
in network byte order. Note that values below 2^16 are reserved
for 16-bit DNS Resorce Record types allocated by IANA [RFC6895].
Values above 2^16 are allocated by the GNUnet Assigned Numbers
Authority [GANA].
DATA the variable-length resource record data payload. The content
is defined by the respective type of the resource record.
Flags indicate metadata surrounding the resource record. An
application creating resource records MUST set all bits to 0 unless
it wants to set the respective flag. As additional flags can be
defined in future protocol versions, if an application or
implementation encounters a flag which it does not recognize, it MUST
be ignored. Any combination of the flags specified below are valid.
Figure 8 illustrates the flag distribution in the 16-bit flag field
of a resource record:
0 13 14 15
+--------...+-------------+-------+---------+
| Reserved |SUPPLEMENTAL |SHADOW |CRITICAL |
+--------...+-------------+-------+---------+
Figure 8: The Resource Record Flag Wire Format.
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CRITICAL If this flag is set, it indicates that processing is
critical. Implementations that do not support the record type or
are otherwise unable to process the record MUST abort resolution
upon encountering the record in the resolution process.
SHADOW If this flag is set, this record MUST be ignored by resolvers
unless all (other) records of the same record type have expired.
Used to allow zone publishers to facilitate good performance when
records change by allowing them to put future values of records
into the storage. This way, future values can propagate and can
be cached before the transition becomes active.
SUPPLEMENTAL This is a supplemental record. It is provided in
addition to the other records. This flag indicates that this
record is not explicitly managed alongside the other records under
the respective name but might be useful for the application.
5.1. Zone Delegation Records
This section defines the initial set of zone delegation record types.
Any implementation SHOULD support all zone types defined here and MAY
support any number of additional delegation records defined in the
GNU Name System Record Types registry (see Section 10). Not
supporting some zone types will result in resolution failures in case
the respective zone type is encountered. This is be a valid choice
if some zone delegation record types have been determined to be
cryptographically insecure. Zone delegation records MUST NOT be
stored and published under the apex label. A zone delegation record
type value is the same as the respective ztype value. The ztype
defines the cryptographic primitives for the zone that is being
delegated to. A zone delegation record payload contains the public
key of the zone to delegate to. A zone delegation record MUST have
the CRITICAL flag set and MUST be the only non-supplemental record
under a label. There MAY be inactive records of the same type which
have the SHADOW flag set in order to facilitate smooth key rollovers.
In the following, "||" is the concatenation operator of two byte
strings. The algorithm specification uses character strings such as
GNS labels or constant values. When used in concatenations or as
input to functions the null-terminator of the character strings MUST
NOT be included.
5.1.1. PKEY
In GNS, a delegation of a label to a zone of type "PKEY" is
represented through a PKEY record. The PKEY DATA entry wire format
can be found in Figure 9.
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0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| PUBLIC KEY |
| |
| |
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 9: The PKEY Wire Format.
PUBLIC KEY A 256-bit Ed25519 public key.
For PKEY zones the zone key material is derived using the curve
parameters of the twisted Edwards representation of Curve25519
[RFC7748] (a.k.a. Ed25519) with the ECDSA scheme [RFC6979]. The
following naming convention is used for the cryptographic primitives
of PKEY zones:
d is a 256-bit Ed25519 private key (private scalar).
zk is the Ed25519 public zone key corresponding to d.
p is the prime of edwards25519 as defined in [RFC7748], i.e. 2^255
- 19.
G is the group generator (X(P),Y(P)) of edwards25519 as defined in
[RFC7748].
L is the order of the prime-order subgroup of edwards25519 in
[RFC7748].
KeyGen() The generation of the private scalar d and the curve point
zk := d*G (where G is the group generator of the elliptic curve)
as defined in Section 2.2. of [RFC6979] represents the KeyGen()
function.
The zone type and zone key of a PKEY are 4 + 32 bytes in length.
This means that a zTLD will always fit into a single label and does
not need any further conversion. Given a label, the output zk' of
the ZKDF(zk,label) function is calculated as follows for PKEY zones:
ZKDF(zk,label):
PRK_h := HKDF-Extract ("key-derivation", zk)
h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
zk' := (h mod L) * zk
return zk'
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The PKEY cryptosystem uses a hash-based key derivation function
(HKDF) as defined in [RFC5869], using SHA-512 [RFC6234] for the
extraction phase and SHA-256 [RFC6234] for the expansion phase.
PRK_h is key material retrieved using an HKDF using the string "key-
derivation" as salt and the zone key as initial keying material. h
is the 512-bit HKDF expansion result and must be interpreted in
network byte order. The expansion information input is a
concatenation of the label and the string "gns". The multiplication
of zk with h is a point multiplication, while the multiplication of d
with h is a scalar multiplication.
The Sign() and Verify() functions for PKEY zones are implemented
using 512-bit ECDSA deterministic signatures as specified in
[RFC6979]. The same functions can be used for derived keys:
SignDerived(d,label,message):
zk := d * G
PRK_h := HKDF-Extract ("key-derivation", zk)
h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
d' := (h * d) mod L
return Sign(d',message)
A signature (R,S) is valid if the following holds:
VerifyDerived(zk,label,message,signature):
zk' := ZKDF(zk,label)
return Verify(zk',message,signature)
The S-Encrypt() and S-Decrypt() functions use AES in counter mode as
defined in [MODES] (CTR-AES-256):
S-Encrypt(zk,label,expiration,plaintext):
PRK_k := HKDF-Extract ("gns-aes-ctx-key", zk)
PRK_n := HKDF-Extract ("gns-aes-ctx-iv", zk)
K := HKDF-Expand (PRK_k, label, 256 / 8)
NONCE := HKDF-Expand (PRK_n, label, 32 / 8)
IV := NONCE || expiration || 0x0000000000000001
return CTR-AES256(K, IV, plaintext)
S-Decrypt(zk,label,expiration,ciphertext):
PRK_k := HKDF-Extract ("gns-aes-ctx-key", zk)
PRK_n := HKDF-Extract ("gns-aes-ctx-iv", zk)
K := HKDF-Expand (PRK_k, label, 256 / 8)
NONCE := HKDF-Expand (PRK_n, label, 32 / 8)
IV := NONCE || expiration || 0x0000000000000001
return CTR-AES256(K, IV, ciphertext)
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The key K and counter IV are derived from the record label and the
zone key zk using a hash-based key derivation function (HKDF) as
defined in [RFC5869]. SHA-512 [RFC6234] is used for the extraction
phase and SHA-256 [RFC6234] for the expansion phase. The output
keying material is 32 bytes (256 bits) for the symmetric key and 4
bytes (32 bits) for the nonce. The symmetric key K is a 256-bit AES
[RFC3826] key.
The nonce is combined with a 64-bit initialization vector and a
32-bit block counter as defined in [RFC3686]. The block counter
begins with the value of 1, and it is incremented to generate
subsequent portions of the key stream. The block counter is a 32-bit
integer value in network byte order. The initialization vector is
the expiration time of the resource record block in network byte
order. The resulting counter (IV) wire format can be found in
Figure 10.
0 8 16 24 32
+-----+-----+-----+-----+
| NONCE |
+-----+-----+-----+-----+
| EXPIRATION |
| |
+-----+-----+-----+-----+
| BLOCK COUNTER |
+-----+-----+-----+-----+
Figure 10: The Block Counter Wire Format.
5.1.2. EDKEY
In GNS, a delegation of a label to a zone of type "EDKEY" is
represented through a EDKEY record. The EDKEY DATA entry wire format
is illustrated in Figure 11.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| PUBLIC KEY |
| |
| |
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 11: The EDKEY DATA Wire Format.
PUBLIC KEY A 256-bit EdDSA zone key.
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For EDKEY zones the zone key material is derived using the curve
parameters of the twisted edwards representation of Curve25519
[RFC7748] (a.k.a. Ed25519) with the Ed25519 scheme [ed25519] as
specified in [RFC8032]. The following naming convention is used for
the cryptographic primitives of EDKEY zones:
d is a 256-bit EdDSA private key.
a is is an integer derived from d using the SHA-512 hash function as
defined in [RFC8032].
zk is the EdDSA public key corresponding to d. It is defined as the
curve point a*G where G is the group generator of the elliptic
curve as defined in [RFC8032].
p is the prime of edwards25519 as defined in [RFC8032], i.e. 2^255
- 19.
G is the group generator (X(P),Y(P)) of edwards25519 as defined in
[RFC8032].
L is the order of the prime-order subgroup of edwards25519 in
[RFC8032].
KeyGen() The generation of the private key d and the associated
public key zk := a*G where G is the group generator of the
elliptic curve and a is an integer derived from d using the
SHA-512 hash function as defined in Section 5.1.5 of [RFC8032]
represents the KeyGen() function.
The zone type and zone key of an EDKEY are 4 + 32 bytes in length.
This means that a zTLD will always fit into a single label and does
not need any further conversion.
The "EDKEY" ZKDF instantiation is based on [Tor224]. The calculation
of a is defined in Section 5.1.5 of [RFC8032]. Given a label, the
output of the ZKDF function is calculated as follows:
ZKDF(zk,label):
/* Calculate the blinding factor */
PRK_h := HKDF-Extract ("key-derivation", zk)
h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
/* Ensure that h == h mod L */
h[31] &= 7
zk' := h * zk
return zk'
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Implementers SHOULD employ a constant time scalar multiplication for
the constructions above to protect against timing attacks.
Otherwise, timing attacks could leak private key material if an
attacker can predict when a system starts the publication process.
The EDKEY cryptosystem uses a hash-based key derivation function
(HKDF) as defined in [RFC5869], using SHA-512 [RFC6234] for the
extraction phase and HMAC-SHA256 [RFC6234] for the expansion phase.
PRK_h is key material retrieved using an HKDF using the string "key-
derivation" as salt and the zone key as initial keying material. The
blinding factor h is the 512-bit HKDF expansion result. The
expansion information input is a concatenation of the label and the
string "gns". The result of the HKDF must be clamped and interpreted
in network byte order. a is the 256-bit integer corresponding to the
256-bit private key d. The multiplication of zk with h is a point
multiplication, while the division and multiplication of a and a1
with the co-factor are integer operations.
The Sign(d,message) and Verify(zk,message,signature) procedures MUST
be implemented as defined in [RFC8032].
Signatures for EDKEY zones use a derived private scalar d' which is
not compliant with [RFC8032]. As the corresponding private key to
the derived private scalar is not known, it is not possible to
deterministically derive the signature part R according to [RFC8032].
Instead, signatures MUST be generated as follows for any given
message and private zone key: A nonce is calculated from the highest
32 bytes of the expansion of the private key d and the blinding
factor h. The nonce is then hashed with the message to r. This way,
the full derivation path is included in the calculation of the R
value of the signature, ensuring that it is never reused for two
different derivation paths or messages.
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SignDerived(d,label,message):
/* Key expansion */
dh := SHA-512 (d)
/* EdDSA clamping */
a := dh[0..31]
a[0] &= 248
a[31] &= 127
a[31] |= 64
/* Calculate zk corresponding to d */
zk := a * G
/* Calculate blinding factor */
PRK_h := HKDF-Extract ("key-derivation", zk)
h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
/* Ensure that h == h mod L */
h[31] &= 7
zk' := h * zk
a1 := a >> 3
a2 := (h * a1) mod L
d' := a2 << 3
nonce := SHA-256 (dh[32..63] || h)
r := SHA-512 (nonce || message)
R := r * G
S := r + SHA-512(R || zk' || message) * d' mod L
return (R,S)
A signature (R,S) is valid if the following holds:
VerifyDerived(zk,label,message,signature):
zk' := ZKDF(zk,label)
(R,S) := signature
return S * G == R + SHA-512(R, zk', message) * zk'
The S-Encrypt() and S-Decrypt() functions use XSalsa20 as defined in
[XSalsa20] (XSalsa20-Poly1305):
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S-Encrypt(zk,label,expiration,message):
PRK_k := HKDF-Extract ("gns-xsalsa-ctx-key", zk)
PRK_n := HKDF-Extract ("gns-xsalsa-ctx-iv", zk)
K := HKDF-Expand (PRK_k, label, 256 / 8)
NONCE := HKDF-Expand (PRK_n, label, 128 / 8)
IV := NONCE || expiration
return XSalsa20-Poly1305(K, IV, message)
S-Decrypt(zk,label,expiration,ciphertext):
PRK_k := HKDF-Extract ("gns-xsalsa-ctx-key", zk)
PRK_n := HKDF-Extract ("gns-xsalsa-ctx-iv", zk)
K := HKDF-Expand (PRK_k, label, 256 / 8)
NONCE := HKDF-Expand (PRK_n, label, 128 / 8)
IV := NONCE || expiration
return XSalsa20-Poly1305(K, IV, ciphertext)
The result of the XSalsa20-Poly1305 encryption function is the
encrypted ciphertext followed by the 128-bit authentication tag.
Accordingly, the length of encrypted data equals the length of the
data plus the 16 bytes of the authentication tag.
The key K and counter IV are derived from the record label and the
zone key zk using a hash-based key derivation function (HKDF) as
defined in [RFC5869]. SHA-512 [RFC6234] is used for the extraction
phase and SHA-256 [RFC6234] for the expansion phase. The output
keying material is 32 bytes (256 bits) for the symmetric key and 16
bytes (128 bits) for the NONCE. The symmetric key K is a 256-bit
XSalsa20 [XSalsa20] key. No additional authenticated data (AAD) is
used.
The nonce is combined with an 8 byte initialization vector. The
initialization vector is the expiration time of the resource record
block in network byte order. The resulting counter (IV) wire format
is illustrated in Figure 12.
0 8 16 24 32
+-----+-----+-----+-----+
| NONCE |
| |
| |
| |
+-----+-----+-----+-----+
| EXPIRATION |
| |
+-----+-----+-----+-----+
Figure 12: The Counter Block Initialization Vector.
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5.2. Redirection Records
Redirect records are used to redirect resolution. Any implementation
SHOULD support all redirection record types defined here and MAY
support any number of additional redirection records defined in the
GNU Name System Record Types registry (see Section Section 10).
Redirection records MUST have the CRITICAL flag set. Not supporting
some record types can result in resolution failures. This can be a
valid choice if some redirection record types have been determined to
be insecure, or if an application has reasons to not support
redirection to DNS for reasons such as complexity or security.
Redirection records MUST NOT be stored and published under the apex
label.
5.2.1. REDIRECT
A REDIRECT record is the GNS equivalent of a CNAME record in DNS. A
REDIRECT record MUST be the only non-supplemental record under a
label. There MAY be inactive records of the same type which have the
SHADOW flag set in order to facilitate smooth changes of redirection
targets. No other records are allowed. Details on processing of
this record is defined in Section 7.3.1. A REDIRECT DATA entry is
illustrated in Figure 13.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| REDIRECT NAME |
/ /
/ /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 13: The REDIRECT DATA Wire Format.
REDIRECT NAME The name to continue with. The value of a redirect
record can be a regular name, or a relative name. Relative GNS
names are indicated by an extension label (U+002B, "+") as
rightmost label. The string is UTF-8 encoded and 0-terminated.
5.2.2. GNS2DNS
It is possible to delegate a label back into DNS through a GNS2DNS
record. The resource record contains a DNS name for the resolver to
continue with in DNS followed by a DNS server. Both names are in the
format defined in [RFC1034] for DNS names. There MAY be multiple
GNS2DNS records under a label. There MAY also be DNSSEC DS records
or any other records used to secure the connection with the DNS
servers under the same label. There MAY be inactive records of the
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same type(s) which have the SHADOW flag set in order to facilitate
smooth changes of redirection targets. No other non-supplemental
record types are allowed in the same record set. A GNS2DNS DATA
entry is illustrated in Figure 14.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| NAME |
/ /
/ /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
| DNS SERVER NAME |
/ /
/ /
| |
+-----------------------------------------------+
Figure 14: The GNS2DNS DATA Wire Format.
NAME The name to continue with in DNS. The value is UTF-8 encoded
and 0-terminated.
DNS SERVER NAME The DNS server to use. This value can be an IPv4
address in dotted-decimal form or an IPv6 address in colon-
hexadecimal form or a DNS name. It can also be a relative GNS
name ending with a "+" as the rightmost label. The implementation
MUST check the string syntactically for an IP address in the
respective notation before checking for a relative GNS name. If
all three checks fail, the name MUST be treated as a DNS name.
The value is UTF-8 encoded and 0-terminated.
NOTE: If an application uses DNS names obtained from GNS2DNS records
in a DNS request they MUST first be converted to an IDNA compliant
representation [RFC5890].
5.3. Auxiliary Records
This section defines the initial set of auxiliary GNS record types.
Any implementation SHOULD be able to process the specified record
types according to Section 7.3.
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5.3.1. LEHO
This record is used to provide a hint for LEgacy HOstnames:
Applications can use the GNS to lookup IPv4 or IPv6 addresses of
internet services. However, sometimes connecting to such services
does not only require the knowledge of an address and port, but also
requires the canonical DNS name of the service to be transmitted over
the transport protocol. In GNS, legacy host name records provide
applications the DNS name that is required to establish a connection
to such a service. The most common use case is HTTP virtual hosting
and TLS Server Name Indication [RFC6066], where a DNS name must be
supplied in the HTTP "Host"-header and the TLS handshake,
respectively. Using a GNS name in those cases might not work as it
might not be globally unique. Furthermore, even if uniqueness is not
an issue, the legacy service might not even be aware of GNS.
A LEHO resource record is expected to be found together in a single
resource record with an IPv4 or IPv6 address. A LEHO DATA entry is
illustrated in Figure 15.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| LEGACY HOSTNAME |
/ /
/ /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 15: The LEHO DATA Wire Format.
LEGACY HOSTNAME A UTF-8 string (which is not 0-terminated)
representing the legacy hostname.
NOTE: If an application uses a LEHO value in an HTTP request header
(e.g. "Host:" header) it MUST be converted to an IDNA compliant
representation [RFC5890].
5.3.2. NICK
Nickname records can be used by zone administrators to publish a
label that a zone prefers to have used when it is referred to. This
is a suggestion to other zones what label to use when creating a
delegation record (Section 5.1) containing this zone key. This
record SHOULD only be stored under the apex label "@" but MAY be
returned with record sets under any label as a supplemental record.
Section 7.3.5 details how a resolver must process supplemental and
non-supplemental NICK records. A NICK DATA entry is illustrated in
Figure 16.
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0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| NICKNAME |
/ /
/ /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 16: The NICK DATA Wire Format.
NICKNAME A UTF-8 string (which is not 0-terminated) representing the
preferred label of the zone. This string MUST be a valid GNS
label.
5.3.3. BOX
GNS lookups are expected to return all of the required useful
information in one record set. This avoids unnecessary additional
lookups and cryptographically ties together information that belongs
together, making it impossible for an adversarial storage to provide
partial answers that might omit information critical for security.
This general strategy is incompatible with the special labels used by
DNS for SRV and TLSA records. Thus, GNS defines the BOX record
format to box up SRV and TLSA records and include them in the record
set of the label they are associated with. For example, a TLSA
record for "_https._tcp.example.org" will be stored in the record set
of "example.org" as a BOX record with service (SVC) 443 (https) and
protocol (PROTO) 6 (tcp) and record TYPE "TLSA". For reference, see
also [RFC2782]. A BOX DATA entry is illustrated in Figure 17.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| PROTO | SVC | TYPE |
+-----------+-----------------------------------+
| RECORD DATA |
/ /
/ /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 17: The BOX DATA Wire Format.
PROTO the 16-bit protocol number, e.g. 6 for TCP. Note that values
below 2^8 are reserved for 8-bit Internet Protocol numbers
allocated by IANA [RFC5237]. Values above 2^8 are allocated by
the GNUnet Assigned Numbers Authority [GANA]. In network byte
order.
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SVC the 16-bit service value of the boxed record. In case of TCP
and UDP it is the port number. In network byte order.
TYPE is the 32-bit record type of the boxed record. In network byte
order.
RECORD DATA is a variable length field containing the "DATA" format
of TYPE as defined for the respective TYPE in DNS.
6. Record Encoding
Any API which allows storing a value under a 512-bit key and
retrieving one or more values from the key can be used by an
implementation for record storage. To be useful, the API MUST permit
storing at least 176 byte values to be able to support the defined
zone delegation record encodings, and SHOULD allow at least 1024 byte
values. In the following, it is assumed that an implementation
realizes two procedures on top of a storage:
PUT(key,value)
GET(key) -> value
There is no explicit delete function as the deletion of a non-expired
record would require a revocation of the record. In GNS, zones can
only be revoked as a whole. Records automatically expire and it is
under the discretion of the storage as to when to delete the record.
The GNS implementation MUST NOT publish expired resource records.
Any GNS resolver MUST discard expired records returned from the
storage.
Resource records are grouped by their respective labels, encrypted
and published together in a single records block (RRBLOCK) in the
storage under a storage key q as illustrated in Figure 18. The
implementation MUST use the PUT storage procedure in order to update
the zone contents accordingly.
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Local Host | Remote
| Storage
|
| +---------+
| / /|
| +---------+ |
+-----------+ | | | |
| | +---------+PUT(q, RRBLOCK) | | Record | |
| User | | Zone |----------------|->| Storage | |
| | | Master | | | |/
+-----------+ +---------+ | +---------+
| A |
| | Zone records |
| | grouped by label |
| | |
| +---------+ |
|Create / Delete / | /| |
|and Update +---------+ | |
|Local Zones | | | |
| | Local | | |
+-------------->| Zones | | |
| |/ |
+---------+ |
Figure 18: Management and publication of local zones in the
distributed storage.
The storage key is derived from the zone key and the respective label
of the contained records. The required knowledge of both zone key
and label in combination with the similarly derived symmetric secret
keys and blinded zone keys ensure query privacy (see [RFC8324],
Section 3.5). The storage Key derivation and records block creation
using is specified in the following sections and a high-level
overview is illustrated in Figure 19.
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+----------+ +-------+ +------------+ +-------------+
| Zone Key | | Label | | Record Set | | Private Key |
+----------+ +-------+ +------------+ +-------------+
| | | |
| | v |
| | +-----------+ |
| +---------->| S-Encrypt | |
+----------|---------->+-----------+ |
| | | | |
| | | v v
| | | +-------------+
| +---------------|-->| SignDerived |
| | | +-------------+
| | | |
| v v v
| +------+ +---------------+
+----->| ZKDF |------->| Records Block |
+------+ +---------------+
|
v
+------+ +-------------+
| Hash |------->| Storage Key |
+------+ +-------------+
Figure 19: Storage key and records block creation overview.
6.1. The Storage Key
Given a label, the storage key q is derived as follows:
q := SHA-512 (ZKDF(zk, label))
label is a UTF-8 string under which the resource records are
published.
zk is the zone key.
q Is the 512-bit storage key under which the resource records block
is published. It is the SHA-512 hash [RFC6234] over the derived
zone key.
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6.2. The Records Block
GNS records are grouped by their labels and published as a single
block in the storage. The grouped record sets MAY be paired with any
number of supplemental records. Supplemental records MUST have the
supplemental flag set (See Section 5). The contained resource
records are encrypted using a symmetric encryption scheme. A GNS
implementation publishes RRBLOCKs in accordance to the properties and
recommendations of the underlying storage. This can include a
periodic refresh operation to ensure the availability of the
published RRBLOCKs. The GNS RRBLOCK wire format is illustrated in
Figure 20.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIZE | ZONE TYPE |
+-----+-----+-----+-----+-----+-----+-----+-----+
/ ZONE KEY /
/ (BLINDED) /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIGNATURE |
/ /
/ /
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
| EXPIRATION |
+-----+-----+-----+-----+-----+-----+-----+-----+
| BDATA /
/ /
/ |
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 20: The RRBLOCK Wire Format.
SIZE A 32-bit value containing the length of the block in bytes. In
network byte order. While a 32-bit value is used, implementations
MAY refuse to publish blocks beyond a certain size significantly
below 4 GB.
ZONE TYPE is the 32-bit ztype. In network byte order.
ZONE KEY is the blinded zone key "ZKDF(zk, label)" to be used to
verify SIGNATURE. The length and format of the public key depends
on the ztype.
SIGNATURE The signature is computed over the EXPIRATION and BDATA
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fields as detailed in Figure 21. The length and format of the
signature depends on the ztype. The signature is created using
the SignDerived() function of the cryptosystem of the zone (see
Section 4).
EXPIRATION Specifies when the RRBLOCK expires and the encrypted
block SHOULD be removed from the storage and caches as it is
likely stale. However, applications MAY continue to use non-
expired individual records until they expire. The value MUST be
set to the expiration time of the resource record contained within
this block with the smallest expiration time. If a records block
includes shadow records, then the maximum expiration time of all
shadow records with matching type and the expiration times of the
non-shadow records is considered. This is a 64-bit absolute date
in microseconds since midnight (0 hour), January 1, 1970 UTC in
network byte order.
BDATA The encrypted RDATA. Its size is determined by the
S-Encrypt() function of the ztype.
The signature over the public key covers a 32-bit pseudo header
conceptually prefixed to the EXPIRATION and the BDATA fields. The
wire format is illustrated in Figure 21.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIZE | PURPOSE (0x0F) |
+-----+-----+-----+-----+-----+-----+-----+-----+
| EXPIRATION |
+-----+-----+-----+-----+-----+-----+-----+-----+
| BDATA |
/ /
/ /
+-----+-----+-----+-----+-----+-----+-----+-----+
Figure 21: The Wire Format used for creating the signature of the
RRBLOCK.
SIZE A 32-bit value containing the length of the signed data in
bytes in network byte order.
PURPOSE A 32-bit signature purpose flag. The value of this field
MUST be 15. The value is encoded in network byte order. It
defines the context in which the signature is created so that it
cannot be reused in other parts of the protocol including possible
future extensions. The value of this field corresponds to an
entry in the GANA "GNUnet Signature Purpose" registry Section 10.
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EXPIRATION Field as defined in the RRBLOCK message above.
BDATA Field as defined in the RRBLOCK message above.
A symmetric encryption scheme is used to encrypt the resource records
set RDATA into the BDATA field of a GNS RRBLOCK. The wire format of
the RDATA is illustrated in Figure 22.
0 8 16 24 32 40 48 56
+-----+-----+-----+-----+-----+-----+-----+-----+
| EXPIRATION |
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIZE | FLAGS | TYPE |
+-----+-----+-----+-----+-----+-----+-----+-----+
| DATA /
/ /
/ /
+-----+-----+-----+-----+-----+-----+-----+-----+
| EXPIRATION |
+-----+-----+-----+-----+-----+-----+-----+-----+
| SIZE | FLAGS | TYPE |
+-----+-----+-----+-----+-----+-----+-----+-----+
| DATA /
/ /
+-----+-----+-----+-----+-----+-----+-----+-----+
/ PADDING /
/ /
Figure 22: The RDATA Wire Format.
EXPIRATION, SIZE, TYPE, FLAGS and DATA These fields were defined in
the resource record format in Section 5.
PADDING When publishing an RDATA block, the implementation MUST
ensure that the size of the RDATA is a power of two using the
padding field. The field MUST be set to zero and MUST be ignored
on receipt. As a special exception, record sets with (only) a
zone delegation record type are never padded. Note that a record
set with a delegation record MUST NOT contain other records. If
other records are encountered, the whole record block MUST be
discarded.
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7. Name Resolution
Names in GNS are resolved by recursively querying the record storage.
Recursive in this context means that a resolver does not provide
intermediate results for a query to the application. Instead, it
MUST respond to a resolution request with either the requested
resource record or an error message in case the resolution fails.
Figure 23 illustrates how an application requests the lookup of a GNS
name (1). The application MAY provide a desired record type to the
resolver. Subsequently, the Start Zone is determined (2) and the
recursive resolution process started. This is where the desired
record type is used to guide processing. For example, if a zone
delegation record type is requested, the resolution of the apex label
in that zone must be skipped, as the desired record is already found.
Details on how the resolution process is initiated and each iterative
result (3a,3b) in the resolution is processed are provided in the
sections below. The results of the lookup are eventually returned to
the application (4). The implementation MUST NOT filter results
according to the desired record type. Filtering of record sets is
typically done by the application.
Local Host | Remote
| Storage
|
| +---------+
| / /|
| +---------+ |
+-----------+ (1) Name +----------+ | | | |
| | Lookup | | (3a) GET(q) | | Record | |
|Application|----------| Resolver |---------------|->| Storage | |
| |<---------| |<--------------|--| |/
+-----------+ (4) +----------+ (3b) RRBLOCK | +---------+
Records A |
| |
(2) Determination of | |
Start Zone | |
| |
+---------+ |
/ | /| |
+---------+ | |
| | | |
| Start | | |
| Zones | | |
| |/ |
+---------+ |
Figure 23: The recursive GNS resolution process.
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7.1. Start Zones
The resolution of a GNS name starts by identifying the start zone
suffix. Once the start zone suffix is identified, recursive
resolution of the remainder of the name is initiated (Section 7.2).
There are two types of start zone suffixes: zTLDs and local suffix-
to-zone mappings. The choice of available suffix-to-zone mappings is
at the sole discretion of the local system administrator or user.
This property addresses the issue of a single hierarchy with a
centrally controlled root and the related issue of distribution and
management of root servers in DNS (see [RFC8324], Section 3.10 and
3.12).
For names ending with a zTLD the start zone is explicitly given in
the suffix of the name to resolve. In order to ensure uniqueness of
names with zTLDs any implementation MUST use the given zone as start
zone. An implementation MUST first try to interpret the rightmost
label of the given name as the beginning of a zTLD (Section 4.1). If
the rightmost label cannot be (partially) decoded or if it does not
indicate a supported ztype, the name is treated as a normal name and
start zone discovery MUST continue with finding a local suffix-to-
zone mapping. If a valid ztype can be found in the rightmost label,
the implementation MUST try to synthesize and decode the zTLD to
retrieve the start zone key according to Section 4.1. If the zTLD
cannot be synthesized or decoded, the resolution of the name fails
and an error is returned to the application. Otherwise, the zone key
MUST be used as the start zone:
Example name: www.example.<zTLD>
=> Start zone: zk of type ztype
=> Name to resolve from start zone: www.example
For names not ending with a zTLD the resolver MUST determine the
start zone through a local suffix-to-zone mapping. Suffix-to-zone
mappings MUST be configurable through a local configuration file or
database by the user or system administrator. A suffix MAY consist
of multiple GNS labels concatenated with a label separator. If
multiple suffixes match the name to resolve, the longest matching
suffix MUST be used. The suffix length of two results MUST NOT be
equal. This indicates a misconfiguration and the implementation MUST
return an error. The following is a non-normative example mapping of
start zones:
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Example name: www.example.org
Local suffix mappings:
org = zTLD0 := Base32GNS(ztype0||zk0)
example.org = zTLD1 := Base32GNS(ztype1||zk1)
example.com = zTLD2 := Base32GNS(ztype2||zk2)
...
=> Start zone: zk1
=> Name to resolve from start zone: www
The process given above MAY be supplemented with other mechanisms if
the particular application requires a different process. If no start
zone can be discovered, resolution MUST fail and an error MUST be
returned to the application.
7.2. Recursion
In each step of the recursive name resolution, there is an
authoritative zone zk and a name to resolve. The name MAY be empty.
If the name is empty, it is interpreted as the apex label "@".
Initially, the authoritative zone is the start zone.
From here, the following steps are recursively executed, in order:
1. Extract the right-most label from the name to look up.
2. Calculate q using the label and zk as defined in Section 6.1.
3. Perform a storage query GET(q) to retrieve the RRBLOCK.
4. Verify and process the RRBLOCK and decrypt the BDATA contained in
it as defined in Section 6.2.
Upon receiving the RRBLOCK from the storage, as part of verifying the
provided signature, the resolver MUST check that the SHA-512 hash of
the derived authoritative zone key zk' from the RRBLOCK matches the
query q and that the block is not yet expired. If the signature does
not match or the block is expired, the RRBLOCK MUST be ignored and,
if applicable, the storage lookup GET(q) MUST continue to look for
other RRBLOCKs.
7.3. Record Processing
Record processing occurs once a well-formed block has been decrypted.
In record processing, only the valid records obtained are considered.
To filter records by validity, the resolver MUST at least check the
expiration time and the FLAGS field of the respective record. In
particular, SHADOW and SUPPLEMENTAL flags can exclude the record from
being considered. If the resolver encounters a record with the
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CRITICAL flag set and does not support the record type the resolution
MUST be aborted and an error MUST be returned. The information that
the critical record could not be processed SHOULD be returned in the
error description. The implementation MAY choose not to return the
reason for the failure, merely complicating troubleshooting for the
user.
The next steps depend on the context of the name that is being
resolved:
* Case 1: If the filtered record set consists of a single REDIRECT
record, the remainder of the name is prepended to the REDIRECT
data and the recursion is started again from the resulting name.
Details are described in Section 7.3.1.
* Case 2: If the filtered record set consists exclusively of one or
more GNS2DNS records resolution continues with DNS. Details are
described in Section 7.3.2.
* Case 3: If the remainder of the name to be resolved is of the
format "_SERVICE._PROTO" and the record set contains one or more
matching BOX records, the records in the BOX records are the final
result and the recursion is concluded as described in
Section 7.3.3.
* Case 4: If the current record set consist of a single delegation
record, resolution of the remainder of the name is delegated to
the target zone as described in Section 7.3.4.
* Case 5: If the remainder of the name to resolve is empty the
record set is the final result. If any NICK records are in the
final result set, it MUST be processed according to Section 7.3.5.
Otherwise, the final result set is returned.
* Finally, if none of the above is applicable resolution fails and
the resolver MUST return an empty record set.
7.3.1. REDIRECT
If the remaining name is empty and the desired record type is
REDIRECT, in which case the resolution concludes with the REDIRECT
record. If the rightmost label of the redirect name is the extension
label (U+002B, "+"), resolution continues in GNS with the new name in
the current zone. Otherwise, the resulting name is resolved via the
default operating system name resolution process. This can in turn
trigger a GNS name resolution process depending on the system
configuration. In case resolution continues in DNS, the name MUST
first be converted to an IDNA compliant representation [RFC5890].
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In order to prevent infinite loops, the resolver MUST implement loop
detection or limit the number of recursive resolution steps. The
loop detection MUST be effective even if a REDIRECT found in GNS
triggers subsequent GNS lookups via the default operating system name
resolution process.
7.3.2. GNS2DNS
When a resolver encounters one or more GNS2DNS records and the
remaining name is empty and the desired record type is GNS2DNS, the
GNS2DNS records are returned.
Otherwise, it is expected that the resolver first resolves the IP
addresses of the specified DNS name servers. The DNS name MUST be
converted to an IDNA compliant representation [RFC5890] for
resolution in DNS. GNS2DNS records MAY contain numeric IPv4 or IPv6
addresses, allowing the resolver to skip this step. The DNS server
names might themselves be names in GNS or DNS. If the rightmost
label of the DNS server name is the extension label (U+002B, "+"),
the rest of the name is to be interpreted relative to the zone of the
GNS2DNS record. If the DNS server name ends in a label
representation of a zone key, the DNS server name is to be resolved
against the GNS zone zk.
Multiple GNS2DNS records can be stored under the same label, in which
case the resolver MUST try all of them. The resolver MAY try them in
any order or even in parallel. If multiple GNS2DNS records are
present, the DNS name MUST be identical for all of them. Otherwise,
it is not clear which name the resolver is supposed to follow. If
multiple DNS names are present the resolution fails and an
appropriate error is SHOULD be returned to the application.
If there are DNSSEC DS records or any other records used to secure
the connection with the DNS servers stored under the label, the DNS
resolver SHOULD use them to secure the connection with the DNS
server.
Once the IP addresses of the DNS servers have been determined, the
DNS name from the GNS2DNS record is appended to the remainder of the
name to be resolved, and resolved by querying the DNS name server(s).
The synthesized name has to be converted to an IDNA compliant
representation [RFC5890] for resolution in DNS. If such a conversion
is not possible, the resolution MUST be aborted and an error MUST be
returned. The information that the critical record could not be
processed SHOULD be returned in the error description. The
implementation MAY choose not to return the reason for the failure,
merely complicating troubleshooting for the user.
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As the DNS servers specified are possibly authoritative DNS servers,
the GNS resolver MUST support recursive DNS resolution and MUST NOT
delegate this to the authoritative DNS servers. The first successful
recursive name resolution result is returned to the application. In
addition, the resolver SHOULD return the queried DNS name as a
supplemental LEHO record (see Section 5.3.1) with a relative
expiration time of one hour.
Once the transition from GNS into DNS is made through a GNS2DNS
record, there is no "going back". The (possibly recursive)
resolution of the DNS name MUST NOT delegate back into GNS and should
only follow the DNS specifications. For example, names contained in
DNS CNAME records MUST NOT be interpreted by resolvers that support
both DNS and GNS as GNS names.
GNS resolvers SHOULD offer a configuration option to disable DNS
processing to avoid information leakage and provide a consistent
security profile for all name resolutions. Such resolvers would
return an empty record set upon encountering a GNS2DNS record during
the recursion. However, if GNS2DNS records are encountered in the
record set for the apex label and a GNS2DNS record is explicitly
requested by the application, such records MUST still be returned,
even if DNS support is disabled by the GNS resolver configuration.
7.3.3. BOX
When a BOX record is received, a GNS resolver must unbox it if the
name to be resolved continues with "_SERVICE._PROTO". Otherwise, the
BOX record is to be left untouched. This way, TLSA (and SRV) records
do not require a separate network request, and TLSA records become
inseparable from the corresponding address records.
7.3.4. Zone Delegation Records
When the resolver encounters a record of a supported zone delegation
record type (such as PKEY or EDKEY) and the remainder of the name is
not empty, resolution continues recursively with the remainder of the
name in the GNS zone specified in the delegation record.
Whenever a resolver encounters a new GNS zone, it MUST check against
the local revocation list whether the respective zone key has been
revoked. If the zone key was revoked, the resolution MUST fail with
an empty result set.
Implementations MUST NOT allow multiple different zone delegations
under a single label. Implementations MAY support any subset of
ztypes. Handling of Implementations MUST NOT process zone delegation
for the apex label "@". Upon encountering a zone delegation record
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under this label, resolution fails and an error MUST be returned.
The implementation MAY choose not to return the reason for the
failure, merely impacting troubleshooting information for the user.
If the remainder of the name to resolve is empty and a record set was
received containing only a single delegation record, the recursion is
continued with the record value as authoritative zone and the apex
label "@" as remaining name. Except in the case where the desired
record type as specified by the application is equal to the ztype, in
which case the delegation record is returned.
7.3.5. NICK
NICK records are only relevant to the recursive resolver if the
record set in question is the final result which is to be returned to
the application. The encountered NICK records can either be
supplemental (see Section 5) or non-supplemental. If the NICK record
is supplemental, the resolver only returns the record set if one of
the non-supplemental records matches the queried record type. It is
possible that one record set contains both supplemental and non-
supplemental NICK records.
The differentiation between a supplemental and non-supplemental NICK
record allows the application to match the record to the
authoritative zone. Consider the following example:
Query: alice.example (type=A)
Result:
A: 192.0.2.1
NICK: eve (non-Supplemental)
In this example, the returned NICK record is non-supplemental. For
the application, this means that the NICK belongs to the zone
"alice.example" and is published under the apex label along with an A
record. The NICK record is interpreted as: The zone defined by
"alice.example" wants to be referred to as "eve". In contrast,
consider the following:
Query: alice.example (type=AAAA)
Result:
AAAA: 2001:DB8::1
NICK: john (Supplemental)
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In this case, the NICK record is marked as supplemental. This means
that the NICK record belongs to the zone "example" and is published
under the label "alice" along with an A record. The NICK record
should be interpreted as: The zone defined by "example" wants to be
referred to as "john". This distinction is likely useful for other
records published as supplemental.
8. Internationalization and Character Encoding
All names in GNS are encoded in UTF-8 [RFC3629]. Labels MUST be
canonicalized using Normalization Form C (NFC) [Unicode-UAX15]. This
does not include any DNS names found in DNS records, such as CNAME
record data, which is internationalized through the IDNA
specifications [RFC5890].
9. Security and Privacy Considerations
9.1. Availability
In order to ensure availability of records beyond their absolute
expiration times, implementations MAY allow to locally define
relative expiration time values of records. Records can then be
published recurringly with updated absolute expiration times by the
implementation.
Implementations MAY allow users to manage private records in their
zones that are not published in the storage. Private records are
considered just like regular records when resolving labels in local
zones, but their data is completely unavailable to non-local users.
9.2. Agility
The security of cryptographic systems depends on both the strength of
the cryptographic algorithms chosen and the strength of the keys used
with those algorithms. The security also depends on the engineering
of the protocol used by the system to ensure that there are no non-
cryptographic ways to bypass the security of the overall system.
This is why developers of applications managing GNS zones SHOULD
select a default ztype considered secure at the time of releasing the
software. For applications targeting end users that are not expected
to understand cryptography, the application developer MUST NOT leave
the ztype selection of new zones to end users.
This document concerns itself with the selection of cryptographic
algorithms used in GNS. The algorithms identified in this document
are not known to be broken (in the cryptographic sense) at the
current time, and cryptographic research so far leads us to believe
that they are likely to remain secure into the foreseeable future.
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However, this is not necessarily forever, and it is expected that new
revisions of this document will be issued from time to time to
reflect the current best practices in this area.
In terms of crypto-agility, whenever the need for an updated
cryptographic scheme arises to, for example, replace ECDSA over
Ed25519 for PKEY records it can simply be introduced through a new
record type. Zone administrators can then replace the delegation
record type for future records. The old record type remains and
zones can iteratively migrate to the updated zone keys. To ensure
that implementations correctly generate an error message when
encountering a ztype that they do not support, current and future
delegation records must always have the CRITICAL flag set.
9.3. Cryptography
The following considerations provide background on the design choices
of the ztypes specified in this document. When specifying new ztypes
as per Section 4, the same considerations apply.
GNS PKEY zone keys use ECDSA over Ed25519. This is an unconventional
choice, as ECDSA is usually used with other curves. However,
standardized ECDSA curves are problematic for a range of reasons
described in the Curve25519 and EdDSA papers [ed25519]. Using EdDSA
directly is also not possible, as a hash function is used on the
private key which destroys the linearity that the key blinding in GNS
depends upon. We are not aware of anyone suggesting that using
Ed25519 instead of another common curve of similar size would lower
the security of ECDSA. GNS uses 256-bit curves because that way the
encoded (public) keys fit into a single DNS label, which is good for
usability.
In order to ensure ciphertext indistinguishability, care must be
taken with respect to the initialization vector in the counter block.
In our design, the IV always includes the expiration time of the
record block. When applications store records with relative
expiration times, monotonicity is implicitly ensured because each
time a block is published into the storage, its IV is unique as the
expiration time is calculated dynamically and increases monotonically
with the system time. Still, an implementation MUST ensure that when
relative expiration times are decreased, the expiration time of the
next record block MUST be after the last published block. For
records where an absolute expiration time is used, the implementation
MUST ensure that the expiration time is always increased when the
record data changes. For example, the expiration time on the wire
could be increased by a single microsecond even if the user did not
request a change. In case of deletion of all resource records under
a label, the implementation MUST keep track of the last absolute
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expiration time of the last published resource block.
Implementations MAY define and use a special record type as a
tombstone that preserves the last absolute expiration time, but then
MUST take care to not publish a block with this record. When new
records are added under this label later, the implementation MUST
ensure that the expiration times are after the last published block.
Finally, in order to ensure monotonically increasing expiration times
the implementation MUST keep a local record of the last time obtained
from the system clock, so as to construct a monotonic clock in case
the system clock jumps backwards.
9.4. Abuse Mitigation
GNS names are UTF-8 strings. Consequently, GNS faces similar issues
with respect to name spoofing as DNS does for internationalized
domain names. In DNS, attackers can register similar sounding or
looking names (see above) in order to execute phishing attacks. GNS
zone administrators must take into account this attack vector and
incorporate rules in order to mitigate it.
Further, DNS can be used to combat illegal content on the internet by
having the respective domains seized by authorities. However, the
same mechanisms can also be abused in order to impose state
censorship, which is one of the motivations behind GNS. In GNS, TLDs
are not enumerable. By design, the start zone of the resolver is
defined locally and hence such a seizure is difficult and ineffective
in GNS.
9.5. Zone Management
In GNS, zone administrators need to manage and protect their zone
keys. Once a zone key is lost, it cannot be recovered or revoked.
Revocation messages can be pre-calculated if revocation is required
in case a zone key is lost. Zone administrators, and for GNS this
includes end-users, are required to responsibly and diligently
protect their cryptographic keys. GNS supports signing records in
advance ("offline") in order to support processes which aim to
protect private keys such as air gaps.
Similarly, users are required to manage their local start zone
configuration. In order to ensure integrity and availability or
names, users must ensure that their local start zone information is
not compromised or outdated. It can be expected that the processing
of zone revocations and an initial start zone is provided with a GNS
implementation ("drop shipping"). Shipping an initial start zone
configuration effectively establishes a root zone. Extension and
customization of the zone is at the full discretion of the user.
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While implementations following this specification will be
interoperable, if two implementations connect to different storages
they are mutually unreachable. This can lead to a state where a
record exists in the global namespace for a particular name, but the
implementation is not communicating with the storage and is hence
unable to resolve it. This situation is similar to a split-horizon
DNS configuration. Which storages are implemented usually depends on
the application it is built for. The storage used will most likely
depend on the specific application context using GNS resolution. For
example, one application is the resolution of hidden services within
the Tor network, which would suggest using Tor routers for storage.
Implementations of "aggregated" storages are conceivable, but are
expected to be the exception.
9.6. DHTs as Storage
This document does not specify the properties of the underlying
storage which is required by any GNS implementation. It is important
to note that the properties of the underlying storage are directly
inherited by the GNS implementation. This includes both security as
well as other non-functional properties such as scalability and
performance. Implementers should take great care when selecting or
implementing a DHT for use as storage in a GNS implementation. DHTs
with reasonable security and performance properties exist [R5N]. It
should also be taken into consideration that GNS implementations
which build upon different DHT overlays are unlikely to be
interoperable with each other.
9.7. Revocations
Zone administrators are advised to pre-generate zone revocations and
to securely store the revocation information in case the zone key is
lost, compromised or replaced in the future. Pre-calculated
revocations can cease to be valid due to expirations or protocol
changes such as epoch adjustments. Consequently, implementers and
users must take precautions in order to manage revocations
accordingly.
Revocation payloads do not include a 'new' key for key replacement.
Inclusion of such a key would have two major disadvantages:
1. If a revocation is published after a private key was compromised,
allowing key replacement would be dangerous: if an adversary took
over the private key, the adversary could then broadcast a
revocation with a key replacement. For the replacement, the
compromised owner would have no chance to issue even a
revocation. Thus, allowing a revocation message to replace a
private key makes dealing with key compromise situations worse.
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2. Sometimes, key revocations are used with the objective of
changing cryptosystems. Migration to another cryptosystem by
replacing keys via a revocation message would only be secure as
long as both cryptosystems are still secure against forgery.
Such a planned, non-emergency migration to another cryptosystem
should be done by running zones for both cipher systems in
parallel for a while. The migration would conclude by revoking
the legacy zone key only once it is deemed no longer secure, and
hopefully after most users have migrated to the replacement.
9.8. Zone Privacy
GNS does not support authenticated denial of existence of names
within a zone. Record blocks are published in encrypted form using
keys derived from the zone key and record label. Zone administrators
should carefully consider if the label and zone key is public or if
those should be used and considered as a shared secret. Unlike zone
keys, labels can also be guessed by an attacker in the network
observing queries and responses. Given a known and targeted zone
key, the use of well known or easily guessable labels effectively
results in general disclosure of the records to the public. If the
labels and hence the records should be kept secret except to those
knowing a secret label and the zone in which to look, the label must
be chosen accordingly. It is recommended to then use a label with
sufficient entropy as to prevent guessing attacks.
It should be noted that this attack on labels only applies if the
zone key is somehow disclosed to the adversary. GNS itself does not
disclose it during a lookup or when resource records are published as
the zone keys are blinded beforehand. However, zone keys do become
public during revocation.
9.9. Namespace Ambiguity
Some GNS names are indistinguishable from DNS names in their
respective common display format [RFC8499] or other special-use
domain names [RFC6761]. Given such a name it is ambiguous which name
system should be used by an application in order to resolve it. This
poses a risk when trying to resolve a name through DNS when it is
actually a GNS name. In such a case, the GNS name is likely to be
leaked as part of the DNS resolution.
In order to prevent disclosure of queried GNS names it is RECOMMENDED
that GNS-aware applications try to resolve a given name in GNS before
any other method taking into account potential suffix-to-zone
mappings and zTLDs. Suffix-to-zone mappings are expected to be
configured by the user or local administrator and as such the
resolution in GNS is in line with user expectations even if the name
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could also be resolved through DNS. If no suffix-to-zone mapping for
the name exists and no zTLD is found, resolution MAY continue with
other methods such as DNS. If a suffix-to-zone mapping for the name
exists or the name ends with a zTLD, it MUST be resolved using GNS
and resolution MUST NOT continue by any other means independent of
the GNS resolution result.
Mechanisms such as the Name Service Switch (NSS) of Unix-like
operating systems are an example of how such a resolution process can
be implemented and used. It allows system administrators to
configure host name resolution precedence and is integrated with the
system resolver implementation.
The user or system administrator MAY configure one or more unique
suffixes for all suffix-to-zone mappings. If this suffix is a
special-use domain name for GNS or an unreserved DNS TLD, this
prevents namespace ambiguity through local configuration.
10. GANA Considerations
GANA [GANA] manages the "GNU Name System Record Types" registry.
Each entry has the following format:
* Name: The name of the record type (case-insensitive ASCII string,
restricted to alphanumeric characters. For zone delegation
records, the assigned number represents the ztype value of the
zone.
* Number: 32-bit, above 65535
* Comment: Optionally, a brief English text describing the purpose
of the record type (in UTF-8)
* Contact: Optionally, the contact information of a person to
contact for further information.
* References: Optionally, references describing the record type
(such as an RFC)
The registration policy for this registry is "First Come First
Served". This policy is modeled on that described in [RFC8126], and
describes the actions taken by GANA:
Adding new records is possible after expert review, using a first-
come-first-served policy for unique name allocation. Experts are
responsible to ensure that the chosen "Name" is appropriate for the
record type. The registry will assign a unique number for the entry.
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The current contact(s) for expert review are reachable at gns-
registry@gnunet.org.
Any request MUST contain a unique name and a point of contact. The
contact information MAY be added to the registry given the consent of
the requester. The request MAY optionally also contain relevant
references as well as a descriptive comment as defined above.
GANA has assigned numbers for the record types defined in this
specification in the "GNU Name System Record Types" registry as
listed in Figure 24.
Number | Name | Contact | References | Comment
-------+---------+---------+------------+-------------------------
65536 | PKEY | N/A | [This.I-D] | GNS zone delegation (PKEY)
65537 | NICK | N/A | [This.I-D] | GNS zone nickname
65538 | LEHO | N/A | [This.I-D] | GNS legacy hostname
65540 | GNS2DNS | N/A | [This.I-D] | Delegation to DNS
65541 | BOX | N/A | [This.I-D] | Boxed records
65551 | REDIRECT| N/A | [This.I-D] | Redirection record.
65556 | EDKEY | N/A | [This.I-D] | GNS zone delegation (EDKEY)
Figure 24: The GANA Resource Record Registry.
GANA has assigned signature purposes in its "GNUnet Signature
Purpose" registry as listed in Figure 25.
Purpose | Name | References | Comment
--------+-----------------+------------+--------------------------
3 | GNS_REVOCATION | [This.I-D] | GNS zone key revocation
15 | GNS_RECORD_SIGN | [This.I-D] | GNS record set signature
Figure 25: Requested Changes in the GANA GNUnet Signature Purpose
Registry.
11. IANA Considerations
This document makes no requests for IANA action. This section may be
removed on publication as an RFC.
12. Implementation and Deployment Status
There are two implementations conforming to this specification
written in C and Go, respectively. The C implementation as part of
GNUnet [GNUnetGNS] represents the original and reference
implementation. The Go implementation [GoGNS] demonstrates how two
implementations of GNS are interoperable if they are built on top of
the same underlying DHT storage.
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Currently, the GNUnet peer-to-peer network [GNUnet] is an active
deployment of GNS on top of its [R5N] DHT. The [GoGNS]
implementation uses this deployment by building on top of the GNUnet
DHT services available on any GNUnet peer. It shows how GNS
implementations can attach to this existing deployment and
participate in name resolution as well as zone publication.
The self-sovereign identity system re:claimID [reclaim] is using GNS
in order to selectively share identity attributes and attestations
with third parties.
The Ascension tool [Ascension] facilitates the migration of DNS zones
to GNS zones by translating information retrieved from a DNS zone
transfer into a GNS zone.
13. Acknowledgements
The authors thank all reviewers for their comments. In particular,
we thank D. J. Bernstein, S. Bortzmeyer, A. Farrel, E. Lear and
R. Salz for their insightful and detailed technical reviews. We
thank J. Yao and J. Klensin for the internationalization reviews.
We thank NLnet and NGI DISCOVERY for funding work on the GNU Name
System.
14. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782,
DOI 10.17487/RFC2782, February 2000,
<https://www.rfc-editor.org/info/rfc2782>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>.
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[RFC3686] Housley, R., "Using Advanced Encryption Standard (AES)
Counter Mode With IPsec Encapsulating Security Payload
(ESP)", RFC 3686, DOI 10.17487/RFC3686, January 2004,
<https://www.rfc-editor.org/info/rfc3686>.
[RFC3826] Blumenthal, U., Maino, F., and K. McCloghrie, "The
Advanced Encryption Standard (AES) Cipher Algorithm in the
SNMP User-based Security Model", RFC 3826,
DOI 10.17487/RFC3826, June 2004,
<https://www.rfc-editor.org/info/rfc3826>.
[RFC5237] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for
the Protocol Field", BCP 37, RFC 5237,
DOI 10.17487/RFC5237, February 2008,
<https://www.rfc-editor.org/info/rfc5237>.
[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
Key Derivation Function (HKDF)", RFC 5869,
DOI 10.17487/RFC5869, May 2010,
<https://www.rfc-editor.org/info/rfc5869>.
[RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework",
RFC 5890, DOI 10.17487/RFC5890, August 2010,
<https://www.rfc-editor.org/info/rfc5890>.
[RFC5895] Resnick, P. and P. Hoffman, "Mapping Characters for
Internationalized Domain Names in Applications (IDNA)
2008", RFC 5895, DOI 10.17487/RFC5895, September 2010,
<https://www.rfc-editor.org/info/rfc5895>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>.
[RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA
Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
April 2013, <https://www.rfc-editor.org/info/rfc6895>.
[RFC6979] Pornin, T., "Deterministic Usage of the Digital Signature
Algorithm (DSA) and Elliptic Curve Digital Signature
Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August
2013, <https://www.rfc-editor.org/info/rfc6979>.
[RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
for Security", RFC 7748, DOI 10.17487/RFC7748, January
2016, <https://www.rfc-editor.org/info/rfc7748>.
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[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/info/rfc8032>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>.
[RFC9106] Biryukov, A., Dinu, D., Khovratovich, D., and S.
Josefsson, "Argon2 Memory-Hard Function for Password
Hashing and Proof-of-Work Applications", RFC 9106,
DOI 10.17487/RFC9106, September 2021,
<https://www.rfc-editor.org/info/rfc9106>.
[GANA] GNUnet e.V., "GNUnet Assigned Numbers Authority (GANA)",
April 2020, <https://gana.gnunet.org/>.
[MODES] Dworkin, M., "Recommendation for Block Cipher Modes of
Operation: Methods and Techniques", December 2001,
<https://doi.org/10.6028/NIST.SP.800-38A>.
[CrockfordB32]
Douglas, D., "Base32", March 2019,
<https://www.crockford.com/base32.html>.
[XSalsa20] Bernstein, D., "Extending the Salsa20 nonce", 2011,
<https://cr.yp.to/snuffle/xsalsa-20110204.pdf>.
[Unicode-UAX15]
The Unicode Consortium, "Unicode Standard Annex #15:
Unicode Normalization Forms, Revision 31", September 2009,
<http://www.unicode.org/reports/tr15/tr15-31.html>.
[Unicode-UTS46]
The Unicode Consortium, "Unicode Technical Standard #46:
Unicode IDNA Compatibility Processing, Revision 27",
August 2021, <https://www.unicode.org/reports/tr46>.
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15. Informative References
[RFC1928] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., and
L. Jones, "SOCKS Protocol Version 5", RFC 1928,
DOI 10.17487/RFC1928, March 1996,
<https://www.rfc-editor.org/info/rfc1928>.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC4033, March 2005,
<https://www.rfc-editor.org/info/rfc4033>.
[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Extensions: Extension Definitions", RFC 6066,
DOI 10.17487/RFC6066, January 2011,
<https://www.rfc-editor.org/info/rfc6066>.
[RFC7363] Maenpaa, J. and G. Camarillo, "Self-Tuning Distributed
Hash Table (DHT) for REsource LOcation And Discovery
(RELOAD)", RFC 7363, DOI 10.17487/RFC7363, September 2014,
<https://www.rfc-editor.org/info/rfc7363>.
[RFC8324] Klensin, J., "DNS Privacy, Authorization, Special Uses,
Encoding, Characters, Matching, and Root Structure: Time
for Another Look?", RFC 8324, DOI 10.17487/RFC8324,
February 2018, <https://www.rfc-editor.org/info/rfc8324>.
[RFC8806] Kumari, W. and P. Hoffman, "Running a Root Server Local to
a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020,
<https://www.rfc-editor.org/info/rfc8806>.
[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, DOI 10.17487/RFC6761, February 2013,
<https://www.rfc-editor.org/info/rfc6761>.
[Tor224] Goulet, D., Kadianakis, G., and N. Mathewson, "Next-
Generation Hidden Services in Tor", November 2013,
<https://gitweb.torproject.org/torspec.git/tree/
proposals/224-rend-spec-ng.txt#n2135>.
[SDSI] Rivest, R. and B. Lampson, "SDSI - A Simple Distributed
Security Infrastructure", April 1996,
<http://people.csail.mit.edu/rivest/Sdsi10.ps>.
[Kademlia] Maymounkov, P. and D. Mazieres, "Kademlia: A peer-to-peer
information system based on the xor metric.", 2002,
<http://css.csail.mit.edu/6.824/2014/papers/kademlia.pdf>.
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[ed25519] Bernstein, D., Duif, N., Lange, T., Schwabe, P., and B.
Yang, "High-Speed High-Security Signatures", 2011,
<https://ed25519.cr.yp.to/ed25519-20110926.pdf>.
[GNS] Wachs, M., Schanzenbach, M., and C. Grothoff, "A
Censorship-Resistant, Privacy-Enhancing and Fully
Decentralized Name System", 2014,
<https://sci-hub.st/10.1007/978-3-319-12280-9_9>.
[R5N] Evans, N. S. and C. Grothoff, "R5N: Randomized recursive
routing for restricted-route networks", 2011,
<https://sci-hub.st/10.1109/ICNSS.2011.6060022>.
[SecureNS] Grothoff, C., Wachs, M., Ermert, M., and J. Appelbaum,
"Towards secure name resolution on the Internet", 2018,
<https://sci-hub.st/https://doi.org/10.1016/
j.cose.2018.01.018>.
[GNUnetGNS]
GNUnet e.V., "The GNUnet GNS Implementation",
<https://git.gnunet.org/gnunet.git/tree/src/gns>.
[Ascension]
GNUnet e.V., "The Ascension Implementation",
<https://git.gnunet.org/ascension.git>.
[GNUnet] GNUnet e.V., "The GNUnet Project", <https://gnunet.org>.
[reclaim] GNUnet e.V., "The GNUnet Project",
<https://reclaim.gnunet.org>.
[GoGNS] Fix, B., "The Go GNS Implementation",
<https://github.com/bfix/gnunet-
go/tree/master/src/gnunet/service/gns>.
[nsswitch] GNU Project, "System Databases and Name Service Switch",
<https://www.gnu.org/software/libc/manual/html_node/Name-
Service-Switch.html>.
Appendix A. Usage and Migration
This section outlines a number of specific use cases which may help
readers of the technical specification to understand the protocol
better. The considerations below are not meant to be normative for
the GNS protocol in any way. Instead, they are provided in order to
give context and to provide some background on what the intended use
of the protocol is by its designers. Further, this section contains
pointers to migration paths.
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A.1. Zone Dissemination
In order to become a zone owner, it is sufficient to generate a zone
key and a corresponding secret key using a GNS implementation. At
this point, the zone owner can manage GNS resource records in a local
zone database. The resource records can then be published by a GNS
implementation as defined in Section 6. For other users to resolve
the resource records, respective zone information must be
disseminated first. The zone owner may decide to make the zone key
and labels known to a selected set of users only or to make this
information available to the general public.
Sharing zone information directly with specific users not only allows
to potentially preserve zone and record privacy, but also allows the
zone owner and the user to establish strong trust relationships. For
example, a bank may send a customer letter with a QR code which
contains the GNS zone of the bank. This allows the user to scan the
QR code and establish a strong link to the zone of the bank and with
it, for example, the IP address of the online banking web site.
Most Internet services likely want to make their zones available to
the general public as efficiently as possible. First, it is
reasonable to assume that zones which are commanding high levels of
reputation and trust are likely included in the default suffix-to-
zone mappings of implementations. Hence dissemination of a zone
through delegation under such zones can be a viable path in order to
disseminate a zone publicly. For example, it is conceivable that
organizations such as ICANN or country-code top-level domain
registrars also manage GNS zones and offer registration or delegation
services.
Following best practices in particularly those relating to security
and abuse mitigation are methods which allow zone owners and aspiring
registrars to gain a good reputation and eventually trust. This
includes, of course, diligent protection of private zone key
material. Formalizing such best practices is out of scope of this
specification and should be addressed in a separate document and take
Section 9 into account.
A.2. Start Zone Configuration
A user is expected to install a GNS implementation if it is not
already provided through other means such as the operating system or
the browser. It is likely that the implementation ships with a
default start zone configuration. This means that the user is able
to resolve GNS names ending on a zTLD or ending on any suffix-to-name
mapping that is part of the default start zone configuration. At
this point the user may delete or otherwise modify the
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implementation's default configuration:
Deletion of suffix-to-zone mappings may become necessary of the zone
owner referenced by the mapping has lost the trust of the user. For
example, this could be due to lax registration policies resulting in
phishing activities. Modification and addition of new mappings are
means to heal the namespace perforation which would occur in the case
of a deletion or to simply establish a strong direct trust
relationship. However, this requires the user's knowledge of the
respective zone keys. This information must be retrieved out of
band, as illustrated in Appendix A.1: A bank may send the user a
letter with a QR code which contains the GNS zone of the bank. The
user scans the QR code and adds a new suffix-to-name mapping using a
chosen local name for his bank. Other examples include scanning zone
information off the device of a friend, from a storefront, or an
advertisement. The level of trust in the respective zone is
contextual and likely varies from user to user. Trust in a zone
provided through a letter from a bank which may also include a credit
card is certainly different from a zone found on a random
advertisement in the streets. However, this trust is immediately
tangible to the user and can be reflected in the local naming as
well.
User clients should facilitate the modification of the start zone
configuration, for example by providing a QR code reader or other
import mechanisms. Implementations are ideally implemented according
to best practices and addressing applicable points from Section 9.
Formalizing such best practices is out of scope of this
specification.
A.3. Globally Unique Names and the Web
HTTP virtual hosting and TLS Server Name Indication are common use
cases on the Web. HTTP clients supply a DNS name in the HTTP "Host"-
header or as part of the TLS handshake, respectively. This allows
the HTTP server to serve the indicated virtual host with a matching
TLS certificate. The global uniqueness of DNS names are a
prerequisite of those use cases.
Not all GNS names are globally unique. But, any resource record in
GNS can be represented as a concatenation of of a GNS label and the
zTLD of the zone. While not human-readable, this globally unique GNS
name can be leveraged in order to facilitate the same use cases.
Consider the GNS name "www.example.gns" entered in a GNS-aware HTTP
client. At first, "www.example.gns" is resolved using GNS yielding a
record set. Then, the HTTP client determines the virtual host as
follows:
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If there is a LEHO record (Section 5.3.1) containing
"www.example.com" in the record set, then the HTTP client uses this
as the value of the "Host"-header field of the HTTP request:
GET / HTTP/1.1
Host: www.example.com
If there is no LEHO record in the record set, then the HTTP client
tries to find the zone of the record and translates the GNS name into
a globally unique zTLD-representation before using it in the "Host"-
header field of the HTTP request:
GET / HTTP/1.1
Host: www.000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W
In order to determine the canonical representation of the record with
a zTLD, at most two queries are required: First, it must be checked
whether "www.example.gns" itself points to a zone delegation record
which would imply that the record set which was originally resolved
is published under the apex label. If it does, the unique GNS name
is simply the zTLD representation of the delegated zone:
GET / HTTP/1.1
Host: 000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W
If it does not, the unique GNS name is the concatenation of the label
"www" and the zTLD representation of the zone as given in the example
above. In any case, this representation is globally unique. As
such, it can be configured by the HTTP server administrator as a
virtual host name and respective certificates may be issued.
If the HTTP client is a browser, the use of a unique GNS name for
virtual hosting or TLS SNI does not necessarily have to be shown to
the user. For example, the name in the URL bar may remain as
"www.example.gnu" even if the used unique name differs.
A.4. Migration Paths
DNS resolution is built into a variety of existing software
components. Most significantly operating systems and HTTP clients.
This section illustrates possible migration paths for both in order
to enable "legacy" applications to resolve GNS names.
One way to efficiently facilitate the resolution of GNS names are
GNS-enabled DNS server implementations. Local DNS queries are
thereby either rerouted or explicitly configured to be resolved by a
"DNS-to-GNS" server that runs locally. This DNS server tries to
interpret any incoming query for a name as a GNS resolution request.
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If no start zone can be found for the name and it does not end in a
zTLD, the server tries to resolve the name in DNS. Otherwise, the
name is resolved in GNS. In the latter case, the resulting record
set is converted to a DNS answer packet and is returned accordingly.
An implementation of a DNS-to-GNS server can be found in [GNUnet].
A similar approach is to use operating systems extensions such as the
name service switch [nsswitch]. It allows the system administrator
to configure plugins which are used for hostname resolution. A GNS
name service switch plugin can be used in a similar fashion as the
"DNS-to-GNS" server. An implementation of a glibc-compatible
nsswitch plugin for GNS can be found in [GNUnet].
The methods above are usually also effective for HTTP client
software. However, HTTP clients are commonly used in combination
with TLS. TLS certificate validation and in particular server name
indication (SNI) requires additional logic in HTTP clients when GNS
names are in play (Appendix A.3). In order to transparently enable
this functionality for migration purposes, a local GNS-aware SOCKS5
proxy [RFC1928] can be configured to resolve domain names. The
SOCKS5 proxy, similar to the DNS-to-GNS server, is capable of
resolving both GNS and DNS names. In the event of a TLS connection
request with a GNS name, the SOCKS5 proxy can act as a man-in-the-
middle, terminating the TLS connection and establishing a secure
connection against the requested host. In order to establish a
secure connection, the proxy may use LEHO and TLSA records stored in
the record set under the GNS name. The proxy must provide a locally
trusted certificate for the GNS name to the HTTP client which usually
requires the generation and configuration of a local trust anchor in
the browser. An implementation of this SOCKS5 proxy can be found in
[GNUnet].
Appendix B. Example flows
B.1. AAAA Example Resolution
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Local Host | Remote
| Storage
|
| +---------+
| / /|
| +---------+ |
+-----------+ (1) +----------+ | | | |
| | | | (4,6) | | Record | |
|Application|----------| Resolver |---------------|->| Storage | |
| |<---------| |<--------------|--| |/
+-----------+ (8) +----------+ (5,7) | +---------+
A |
| |
(2,3) | |
| |
| |
+---------+ |
/ v /| |
+---------+ | |
| | | |
| Start | | |
| Zones | | |
| |/ |
+---------+ |
Figure 26: Example resolution of an IPv6 address.
1. Lookup AAAA record for name: www.example.gns.
2. Determine start zone for www.example.gns.
3. Start zone: zk0 - Remainder: www.example.
4. Calculate q0=SHA512(ZKDF(zk0, "example")) and initiate GET(q0).
5. Retrieve and decrypt RRBLOCK consisting of a single PKEY record
containing zk1.
6. Calculate q1=SHA512(ZKDF(zk1, "www")) and initiate GET(q1).
7. Retrieve RRBLOCK consisting of a single AAAA record containing
the IPv6 address 2001:db8::1.
8. Return record set to application
B.2. REDIRECT Example Resolution
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Local Host | Remote
| Storage
|
| +---------+
| / /|
| +---------+ |
+-----------+ (1) +----------+ | | | |
| | | | (4,6,8) | | Record | |
|Application|----------| Resolver |----------------|->| Storage | |
| |<---------| |<---------------|--| |/
+-----------+ (10) +----------+ (5,7,9) | +---------+
A |
| |
(2,3) | |
| |
| |
+---------+ |
/ v /| |
+---------+ | |
| | | |
| Start | | |
| Zones | | |
| |/ |
+---------+ |
Figure 27: Example resolution of an IPv6 address with redirect.
1. Lookup AAAA record for name: www.example.tld.
2. Determine start zone for www.example.tld.
3. Start zone: zk0 - Remainder: www.example.
4. Calculate q0=SHA512(ZKDF(zk0, "example")) and initiate GET(q0).
5. Retrieve and decrypt RRBLOCK consisting of a single REDIRECT
record containing zk1.
6. Calculate q1=SHA512(ZKDF(zk1, "www")) and initiate GET(q1).
7. Retrieve and decrypt RRBLOCK consisting of a single REDIRECT
record containing www2.+.
8. Calculate q2=SHA512(ZKDF(zk1, "www2")) and initiate GET(q2).
9. Retrieve and decrypt RRBLOCK consisting of a single AAAA record
containing the IPv6 address 2001:db8::1.
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10. Return record set to application.
B.3. GNS2DNS Example Resolution
Local Host | Remote
| Storage
|
| +---------+
| / /|
| +---------+ |
+-----------+ (1) +----------+ | | | |
| | | | (4) | | Record | |
|Application|----------| Resolver |------------------|->| Storage | |
| |<---------| |<-----------------|--| |/
+-----------+ (8) +----------+ (5) | +---------+
A A |
| | (6,7) |
(2,3) | +----------+ |
| | |
| v |
+---------+ +------------+ |
/ v /| | System DNS | |
+---------+ | | resolver | |
| | | +------------+ |
| Start | | |
| Zones | | |
| |/ |
+---------+ |
Figure 28: Example resolution of an IPv6 address with DNS handover.
1. Lookup AAAA record for name: www.example.gnu
2. Determine start zone for www.example.gnu.
3. Start zone: zk0 - Remainder: www.example.
4. Calculate q0=SHA512(ZKDF(zk0, "example")) and initiate GET(q0).
5. Retrieve and decrypt RRBLOCK consisting of a single GNS2DNS
record containing the name example.com and the DNS server IPv4
address 192.0.2.1.
6. Use system resolver to lookup an AAAA record for the DNS name
www.example.com.
7. Retrieve a DNS reply consisting of a single AAAA record
containing the IPv6 address 2001:db8::1.
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8. Return record set to application.
Appendix C. Base32GNS
This table defines the encode symbol and decode symbol for a given
symbol value. It can be used to implement the encoding by reading it
as: A character "A" or "a" is decoded to a 5 bit value 10 when
decoding. A 5 bit block with a value of 18 is encoded to the
character "J" when encoding. If the bit length of the byte string to
encode is not a multiple of 5 it is padded to the next multiple with
zeroes. In order to further increase tolerance for failures in
character recognition, the letter "U" MUST be decoded to the same
value as the letter "V" in Base32GNS.
Symbol Decode Encode
Value Symbol Symbol
0 0 O o 0
1 1 I i L l 1
2 2 2
3 3 3
4 4 4
5 5 5
6 6 6
7 7 7
8 8 8
9 9 9
10 A a A
11 B b B
12 C c C
13 D d D
14 E e E
15 F f F
16 G g G
17 H h H
18 J j J
19 K k K
20 M m M
21 N n N
22 P p P
23 Q q Q
24 R r R
25 S s S
26 T t T
27 V v U u V
28 W w W
29 X x X
30 Y y Y
31 Z z Z
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Figure 29: The Base32GNS Alphabet Including the Additional U
Encode Symbol.
Appendix D. Test Vectors
The following are test vectors for the Base32GNS encoding used for
zTLDs. The strings are encoded without the zero terminator.
Base32GNS-Encode:
Input string: "Hello World"
Output string: "91JPRV3F41BPYWKCCG"
Input bytes: 474e55204e616d652053797374656d
Output string: "8X75A82EC5PPA82KF5SQ8SBD"
Base32GNS-Decode:
Input string: "91JPRV3F41BPYWKCCG"
Output string: "Hello World"
Input string: "91JPRU3F41BPYWKCCG"
Output string: "Hello World"
The following test vectors can be used by implementations to test for
conformance with this specification. The test vectors include record
sets with a variety of record types and flags for both PKEY and EDKEY
zones. Unless indicated otherwise, the test vectors are provided as
hex byte values. This includes labels as some test vectors contain
UTF-8 multibyte characters to demonstrate internationalized labels.
Zone private key (d, big-endian):
50d7b652a4efeadf
f37396909785e595
2171a02178c8e7d4
50fa907925fafd98
Zone identifier (ztype|zkey):
00010000677c477d
2d93097c85b195c6
f96d84ff61f5982c
2c4fe02d5a11fedf
b0c2901f
zTLD:
000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W
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Label:
7465737464656c65
676174696f6e
Number of records (integer): 1
Record #0 := (
EXPIRATION:
0008c06fb9281580
DATA_SIZE:
0020
TYPE:
00010000
FLAGS: 0001
DATA:
21e3b30ff93bc6d3
5ac8c6e0e13afdff
794cb7b44bbbc748
d259d0a0284dbe84
)
RDATA:
0008c06fb9281580
0020000100010000
21e3b30ff93bc6d3
5ac8c6e0e13afdff
794cb7b44bbbc748
d259d0a0284dbe84
Encryption NONCE|EXPIRATION|BLOCK COUNTER:
e90a00610008c06f
b928158000000001
Encryption key (K):
864e7138eae7fd91
a30136899c132b23
acebdb2cef43cb19
f6bf55b67db9b3b3
Storage key (q):
4adc67c5ecee9f76
986abd71c2224a3d
ce2e917026c9a09d
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fd44cef3d20f55a2
7332725a6c8afbbb
b0f7ec9af1cc4264
1299406b04fd9b5b
5791f86c4b08d5f4
BDATA:
41dc7b5f2176ba59
1998afb9e3c82579
5050afc4b53d68e4
1ed921da89de51e7
da35a295b59c2b8a
aea4399148d50cff
RRBLOCK:
000000a000010000
182bb636eda79f79
5711bc2708adbb24
2a60446ad3c30803
121d03d348b7ceb6
01beab944aff7ccc
51bffb212779c341
87660c625d1ceb59
d5a0a9a2dfe4072d
0f08cd2ab1e9ed63
d3898ff732521b57
317a6c4950e1984d
74df015f9eb72c4a
0008c06fb9281580
41dc7b5f2176ba59
1998afb9e3c82579
5050afc4b53d68e4
1ed921da89de51e7
da35a295b59c2b8a
aea4399148d50cff
Zone private key (d, big-endian):
50d7b652a4efeadf
f37396909785e595
2171a02178c8e7d4
50fa907925fafd98
Zone identifier (ztype|zkey):
00010000677c477d
2d93097c85b195c6
f96d84ff61f5982c
2c4fe02d5a11fedf
b0c2901f
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zTLD:
000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W
Label:
e5a4a9e4b88be784
a1e695b5
Number of records (integer): 3
Record #0 := (
EXPIRATION:
0008c06fb9281580
DATA_SIZE:
0010
TYPE:
0000001c
FLAGS: 0000
DATA:
0000000000000000
00000000deadbeef
)
Record #1 := (
EXPIRATION:
00b00f81b7449b40
DATA_SIZE:
0006
TYPE:
00010001
FLAGS: 8000
DATA:
e6849be7a7b0
)
Record #2 := (
EXPIRATION:
000000016b597108
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DATA_SIZE:
000b
TYPE:
00000010
FLAGS: 4004
DATA:
48656c6c6f20576f
726c64
)
RDATA:
0008c06fb9281580
001000000000001c
0000000000000000
00000000deadbeef
00b00f81b7449b40
0006800000010001
e6849be7a7b00000
00016b597108000b
4004000000104865
6c6c6f20576f726c
6400000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
Encryption NONCE|EXPIRATION|BLOCK COUNTER:
ee9633c10005db3b
cdbd617c00000001
Encryption key (K):
fb3ab5de23bddae1
997aaf7b92c2d271
51408b77af7a41ac
79057c4df5383d01
Storage key (q):
aff0ad6a44097368
429ac476dfa1f34b
ee4c36e7476d07aa
6463ff20915b1005
c0991def91fc3e10
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909f8702c0be4043
6778c711f2ca47d5
5cf0b54d235da977
BDATA:
f8c5e4badf1649d4
04da64df7d9d285f
4072a5f7a2547d56
74227e9b188eb2bb
6b34532f61e08ffb
d5bdea3741e60967
b687f8d8c44c8f6f
120a0f980f393b21
60407be128a74a51
51d6370be56a86ea
e32fdc217596b13f
6fea3fcfea0f4deb
881a25458f505a8f
cfca62d6da56073f
497698613475a1ad
14b7877f9455b0ec
RRBLOCK:
000000f000010000
a51296df757ee275
ca118d4f07fa7aae
5508bcf512aa4112
1429d4a0de9d057e
05c095040b10c7f8
187aa5da12287d1c
2910ff04d6f50af1
fa95382e9f007f75
098f620d1ff7c971
28f40d7458a2d3c7
f048ca3820064bdd
ee9413e9548ec994
0005db3bcdbd617c
f8c5e4badf1649d4
04da64df7d9d285f
4072a5f7a2547d56
74227e9b188eb2bb
6b34532f61e08ffb
d5bdea3741e60967
b687f8d8c44c8f6f
120a0f980f393b21
60407be128a74a51
51d6370be56a86ea
e32fdc217596b13f
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6fea3fcfea0f4deb
881a25458f505a8f
cfca62d6da56073f
497698613475a1ad
14b7877f9455b0ec
Zone private key (d):
5af7020ee1916032
8832352bbc6a68a8
d71a7cbe1b929969
a7c66d415a0d8f65
Zone identifier (ztype|zkey):
000100143cf4b924
032022f0dc505814
53b85d93b047b63d
446c5845cb48445d
db96688f
zTLD:
000G051WYJWJ80S04BRDRM2R2H9VGQCKP13VCFA4DHC4BJT88HEXQ5K8HW
Label:
7465737464656c65
676174696f6e
Number of records (integer): 1
Record #0 := (
EXPIRATION:
0008c06fb9281580
DATA_SIZE:
0020
TYPE:
00010000
FLAGS: 0001
DATA:
21e3b30ff93bc6d3
5ac8c6e0e13afdff
794cb7b44bbbc748
d259d0a0284dbe84
)
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RDATA:
0008c06fb9281580
0020000100010000
21e3b30ff93bc6d3
5ac8c6e0e13afdff
794cb7b44bbbc748
d259d0a0284dbe84
Encryption NONCE|EXPIRATION:
98132ea86859d35c
88bfd317fa991bcb
0008c06fb9281580
Encryption key (K):
85c429a9567aa633
411a9691e9094c45
281672be586034aa
e4a2a2cc716159e2
Storage key (q):
abaabac0e1249459
75988395aac0241e
5559c41c4074e255
7b9fe6d154b614fb
cdd47fc7f51d786d
c2e0b1ece76037c0
a1578c384ec61d44
5636a94e880329e9
BDATA:
9cc455a129331943
5993cb3d67179ec0
6ea8d8894e904a0c
35e91c5c2ff2ed93
9cc2f8301231f44e
592a4ac87e4998b9
4625c64af51686a2
b36a2b2892d44f2d
RRBLOCK:
000000b000010014
9bf233198c6d53bb
dbac495cabd91049
a684af3f4051baca
b0dcf21c8cf27a1a
44d240d07902f490
b7c43ef00758abce
8851c18c70ac6df9
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7a88f79211cf875f
784885ca3e349ec4
ca892b9ff084c535
8965b8e74a231595
2d4c8c06521c2f0c
0008c06fb9281580
9cc455a129331943
5993cb3d67179ec0
6ea8d8894e904a0c
35e91c5c2ff2ed93
9cc2f8301231f44e
592a4ac87e4998b9
4625c64af51686a2
b36a2b2892d44f2d
Zone private key (d):
5af7020ee1916032
8832352bbc6a68a8
d71a7cbe1b929969
a7c66d415a0d8f65
Zone identifier (ztype|zkey):
000100143cf4b924
032022f0dc505814
53b85d93b047b63d
446c5845cb48445d
db96688f
zTLD:
000G051WYJWJ80S04BRDRM2R2H9VGQCKP13VCFA4DHC4BJT88HEXQ5K8HW
Label:
e5a4a9e4b88be784
a1e695b5
Number of records (integer): 3
Record #0 := (
EXPIRATION:
0008c06fb9281580
DATA_SIZE:
0010
TYPE:
0000001c
FLAGS: 0000
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DATA:
0000000000000000
00000000deadbeef
)
Record #1 := (
EXPIRATION:
00b00f81b7449b40
DATA_SIZE:
0006
TYPE:
00010001
FLAGS: 8000
DATA:
e6849be7a7b0
)
Record #2 := (
EXPIRATION:
000000016b597108
DATA_SIZE:
000b
TYPE:
00000010
FLAGS: 4004
DATA:
48656c6c6f20576f
726c64
)
RDATA:
0008c06fb9281580
001000000000001c
0000000000000000
00000000deadbeef
00b00f81b7449b40
0006800000010001
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e6849be7a7b00000
00016b597108000b
4004000000104865
6c6c6f20576f726c
6400000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
Encryption NONCE|EXPIRATION:
bb0d3f0fbd224277
50da5d691216e6c9
0005db3bcdbd7769
Encryption key (K):
3df805bd6687aa14
209628c244b11191
88c3925637a41e5d
76496c2945dc377b
Storage key (q):
baf82177eec081e0
74a7da47ffc64877
58fb0df01a6c7fbb
52fc8a31bef029af
74aa0dc15ab8e2fa
7a54b4f5f637f615
8fa7f03c3fcebe78
d3f9d640aac0d1ed
BDATA:
6f79a9fd28bc5e38
2fc931ed22931797
326fdd698129fc47
8a639e902b411088
0a45037c667ff769
5f09c4a7f4f3471a
b2365bf3af79e953
697f1e35f93bd1ad
876971ce70527a3b
82c098d23fffd4a4
0057b694bec43416
4fb83c12b1f4570f
69a28f3bc3b7d838
b2619f6b8e1723ba
78c4b7ce19ef3f39
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0405b63f7ce00216
1bdd7f5e9b3622bc
1af2d4ca84fd5fc5
RRBLOCK:
0000010000010014
74f90068f1676953
52a8a6c2eb984898
c53acca0980470c6
c81264cbdd78ad11
13b6b78358a88de7
3c5d22f73f1ad588
ee6f07d13410a2f5
15a074872608ec02
ef9020fdeb4266bf
1177c7e57e786059
97032a3f71f7216c
894e073ac77f2a0d
0005db3bcdbd7769
6f79a9fd28bc5e38
2fc931ed22931797
326fdd698129fc47
8a639e902b411088
0a45037c667ff769
5f09c4a7f4f3471a
b2365bf3af79e953
697f1e35f93bd1ad
876971ce70527a3b
82c098d23fffd4a4
0057b694bec43416
4fb83c12b1f4570f
69a28f3bc3b7d838
b2619f6b8e1723ba
78c4b7ce19ef3f39
0405b63f7ce00216
1bdd7f5e9b3622bc
1af2d4ca84fd5fc5
The following is an example revocation for a zone:
Zone private key (d, big-endian scalar):
6fea32c05af58bfa
979553d188605fd5
7d8bf9cc263b78d5
f7478c07b998ed70
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Zone identifier (ztype|zkey):
000100002ca223e8
79ecc4bbdeb5da17
319281d63b2e3b69
55f1c3775c804a98
d5f8ddaa
Encoded zone identifier (zTLD):
000G001CM8HYGYFCRJXXXDET2WRS50EP7CQ3PTANY71QEQ409ACDBY6XN8
Difficulty (5 base difficulty + 2 epochs): 7
Signed message:
0000003400000003
0005d66da3598127
000100002ca223e8
79ecc4bbdeb5da17
319281d63b2e3b69
55f1c3775c804a98
d5f8ddaa
Proof:
0005d66da3598127
0000395d1827c000
3ab877d07570f2b8
3ab877d07570f332
3ab877d07570f4f5
3ab877d07570f50f
3ab877d07570f537
3ab877d07570f599
3ab877d07570f5cd
3ab877d07570f5d9
3ab877d07570f66a
3ab877d07570f69b
3ab877d07570f72f
3ab877d07570f7c3
3ab877d07570f843
3ab877d07570f8d8
3ab877d07570f91b
3ab877d07570f93a
3ab877d07570f944
3ab877d07570f98a
3ab877d07570f9a7
3ab877d07570f9b0
3ab877d07570f9df
3ab877d07570fa05
3ab877d07570fa3e
3ab877d07570fa63
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3ab877d07570fa84
3ab877d07570fa8f
3ab877d07570fa91
3ab877d07570fad6
3ab877d07570fb0a
3ab877d07570fc0f
3ab877d07570fc43
3ab877d07570fca5
000100002ca223e8
79ecc4bbdeb5da17
319281d63b2e3b69
55f1c3775c804a98
d5f8ddaa053b0259
700039187d1da461
3531502bc4a4eecc
c69900d24f8aac54
30f28fc509270133
1f178e290fe06e82
ce2498ce7b23a340
58e3d6a2f247e92b
c9d7b9ab
Authors' Addresses
Martin Schanzenbach
Fraunhofer AISEC
Lichtenbergstrasse 11
85748 Garching
Germany
Email: martin.schanzenbach@aisec.fraunhofer.de
Christian Grothoff
Berner Fachhochschule
Hoeheweg 80
CH-2501 Biel/Bienne
Switzerland
Email: grothoff@gnunet.org
Bernd Fix
GNUnet e.V.
Boltzmannstrasse 3
85748 Garching
Germany
Email: fix@gnunet.org
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