Network Working Group S. Hollenbeck
Request for Comments: 4310 VeriSign, Inc.
Category: Standards Track November 2005
Domain Name System (DNS) Security Extensions Mapping
for the Extensible Provisioning Protocol (EPP)
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document describes an Extensible Provisioning Protocol (EPP)
extension mapping for the provisioning and management of Domain Name
System security extensions (DNSSEC) for domain names stored in a
shared central repository. Specified in XML, this mapping extends
the EPP domain name mapping to provide additional features required
for the provisioning of DNS security extensions.
Table of Contents
1. Introduction ....................................................2
1.1. Conventions Used in This Document ..........................2
2. Object Attributes ...............................................3
2.1. Delegation Signer Information ..............................3
2.1.1. Public Key Information ..............................3
2.2. Booleans ...................................................3
2.3. Maximum Signature Lifetime Values ..........................4
3. EPP Command Mapping .............................................4
3.1. EPP Query Commands .........................................4
3.1.1. EPP Command .................................4
3.1.2. EPP Command ..................................4
3.1.3. EPP Command ..............................8
3.2. EPP Transform Commands .....................................8
3.2.1. EPP Command ................................8
3.2.2. EPP Command ...............................11
3.2.3. EPP Command ................................11
3.2.4. EPP Command .............................11
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RFC 4310 EPP DNS Security Extensions Mapping November 2005
3.2.5. EPP Command ...............................11
4. Formal Syntax ..................................................15
5. Internationalization Considerations ............................18
6. IANA Considerations ............................................18
7. Security Considerations ........................................18
8. Acknowledgements ...............................................20
9. References .....................................................20
9.1. Normative References ......................................20
9.2. Informative References ....................................21
1. Introduction
This document describes an extension mapping for version 1.0 of the
Extensible Provisioning Protocol (EPP) described in RFC 3730 [1].
This mapping, an extension of the domain name mapping described in
RFC 3731 [2], is specified using the Extensible Markup Language (XML)
1.0 [3] and XML Schema notation ([4], [5]).
The EPP core protocol specification [1] provides a complete
description of EPP command and response structures. A thorough
understanding of the base protocol specification is necessary to
understand the mapping described in this document. Familiarity with
the Domain Name System (DNS) described in RFC 1034 [11] and RFC 1035
[12] and with DNS security extensions described in RFC 4033 [13], RFC
4034 [6], and RFC 4035 [7] is required to understand the DNS security
concepts described in this document.
The EPP mapping described in this document specifies a mechanism for
the provisioning and management of DNS security extensions in a
shared central repository. Information exchanged via this mapping
can be extracted from the repository and used to publish DNSSEC
delegation signer (DS) resource records as described in RFC 4034 [6].
1.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, RFC 2119 [8].
In examples, "C:" represents lines sent by a protocol client, and
"S:" represents lines returned by a protocol server. "////" is used
to note element values that have been shortened to better fit page
boundaries. Indentation and white space in examples is provided only
to illustrate element relationships and is not a mandatory feature of
this protocol.
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XML is case sensitive. Unless stated otherwise, XML specifications
and examples provided in this document MUST be interpreted in the
character case presented in order to develop a conforming
implementation.
2. Object Attributes
This extension adds additional elements to the EPP domain name
mapping [2]. Only new element descriptions are described here.
This document describes operational scenarios in which a client can
create, add, remove, and replace delegation signer (DS) information.
Key data associated with the DS information MAY be provided by the
client, but the server is not obligated to use the key data. The
server operator MAY also issue out-of-band DNS queries to retrieve
the key data from the registered domain's apex in order to evaluate
the received DS information. It is RECOMMENDED that the child zone
operator have this key data online in the DNS tree to allow the
parent zone administrator to validate the data as necessary. The key
data SHOULD have the Secure Entry Point (SEP) bit set as described in
RFC 3757 [9].
2.1. Delegation Signer Information
Delegation signer (DS) information is published by a DNS server to
indicate that a child zone is digitally signed and that the parent
zone recognizes the indicated key as a valid zone key for the child
zone. A DS RR contains four fields: a key tag field, a key algorithm
number octet, an octet identifying the digest algorithm used, and a
digest field. See RFC 4034 [6] for specific field formats.
2.1.1. Public Key Information
Public key information provided by a client maps to the DNSKEY RR
presentation field formats described in section 2.2 of RFC 4034 [6].
A DNSKEY RR contains four fields: flags, a protocol octet, an
algorithm number octet, and a public key.
2.2. Booleans
Boolean values MUST be represented in the XML Schema format described
in Part 2 of the W3C XML Schema recommendation [5].
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2.3. Maximum Signature Lifetime Values
Maximum signature lifetime values MUST be represented in seconds
using an extended XML Schema "int" format. The base "int" format,
which allows negative numbers, is described in Part 2 of the W3C XML
Schema recommendation [5]. This format is further restricted to
enforce a minimum value of one.
3. EPP Command Mapping
A detailed description of the EPP syntax and semantics can be found
in the EPP core protocol specification [1]. The command mappings
described here are specifically for use in provisioning and managing
DNS security extensions via EPP.
3.1. EPP Query Commands
EPP provides three commands to retrieve object information:
to determine if an object is known to the server, to retrieve
detailed information associated with an object, and to
retrieve object transfer status information.
3.1.1. EPP Command
This extension does not add any elements to the EPP command
or response described in the EPP domain mapping [2].
3.1.2. EPP Command
This extension does not add any elements to the EPP command
described in the EPP domain mapping [2]. Additional elements are
defined for the response.
When an command has been processed successfully, the EPP
element MUST contain child elements as described in the EPP
domain mapping [2]. In addition, the EPP element MUST
contain a child element that identifies the
extension namespace and the location of the extension schema. The
element contains the following child elements:
One or more elements that describe the delegation
signer data provided by the client for the domain. The element contains the following child elements:
A element that contains a key tag value as
described in section 5.1.1 of RFC 4034 [6].
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A element that contains an algorithm value as
described in section 5.1.2 of RFC 4034 [6].
A element that contains a digest type value
as described in section 5.1.3 of RFC 4034 [6].
A element that contains a digest value as
described in section 5.1.4 of RFC 4034 [6].
An OPTIONAL element that indicates a
child's preference for the number of seconds after signature
generation when the parent's signature on the DS information
provided by the child will expire. A client SHOULD specify the
same value for all elements
associated with a domain. If the is not
present, or if multiple values are
requested, the default signature expiration policy of the
server operator (as determined using an out-of-band mechanism)
applies.
An OPTIONAL element that describes the key
data used as input in the DS hash calculation. The element contains the following child elements:
A element that contains a flags field value
as described in section 2.1.1 of RFC 4034 [6].
A element that contains a protocol field
value as described in section 2.1.2 of RFC 4034 [6].
A element that contains an algorithm number
field value as described in sections 2.1.3 of RFC 4034 [6].
A element that contains an encoded public
key field value as described in sections 2.1.4 of RFC 4034
[6].
Example Response for a Secure Delegation:
S:
S:
S:
S:
S: Command completed successfully
S:
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S:
S:
S: example.com
S: EXAMPLE1-REP
S: jd1234
S: sh8013
S: sh8013
S:
S: ns1.example.com
S: ns2.example.com
S:
S: ns1.example.com
S: ns2.example.com
S: ClientX
S: ClientY
S: 1999-04-03T22:00:00.0Z
S: ClientX
S: 1999-12-03T09:00:00.0Z
S: 2005-04-03T22:00:00.0Z
S: 2000-04-08T09:00:00.0Z
S:
S: 2fooBAR
S:
S:
S:
S:
S:
S:
S: 12345
S: 3
S: 1
S: 49FD46E6C4B45C55D4AC
S:
S:
S:
S:
S: ABC-12345
S: 54322-XYZ
S:
S:
S:
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Example Response for a Secure Delegation with OPTIONAL Data:
S:
S:
S:
S:
S: Command completed successfully
S:
S:
S:
S: example.com
S: EXAMPLE1-REP
S: jd1234
S: sh8013
S: sh8013
S:
S: ns1.example.com
S: ns2.example.com
S:
S: ns1.example.com
S: ns2.example.com
S: ClientX
S: ClientY
S: 1999-04-03T22:00:00.0Z
S: ClientX
S: 1999-12-03T09:00:00.0Z
S: 2005-04-03T22:00:00.0Z
S: 2000-04-08T09:00:00.0Z
S:
S: 2fooBAR
S:
S:
S:
S:
S:
S:
S: 12345
S: 3
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S: 1
S: 49FD46E6C4B45C55D4AC
S: 604800
S:
S: 256
S: 3
S: 1
S: AQPJ////4Q==
S:
S:
S:
S:
S:
S: ABC-12345
S: 54322-XYZ
S:
S:
S:
An EPP error response MUST be returned if an command can not
be processed for any reason.
3.1.3. EPP Command
This extension does not add any elements to the EPP
command or response described in the EPP domain mapping
[2].
3.2. EPP Transform Commands
EPP provides five commands to transform objects: to create
an instance of an object, to delete an instance of an
object, to extend the validity period of an object,
to manage object sponsorship changes, and to
change information associated with an object.
3.2.1. EPP Command
This extension defines additional elements for the EPP
command described in the EPP domain mapping [2]. No additional
elements are defined for the EPP response.
The EPP command provides a transform operation that allows a
client to create a domain object. In addition to the EPP command
elements described in the EPP domain mapping [2], the command MUST
contain an element. The element MUST contain
a child element that identifies the extension
namespace and the location of the extension schema. The element MUST contain one or more elements.
Child elements of the element are described in
Section 3.1.2.
The element contains OPTIONAL and
elements. The server MUST abort command processing
and respond with an appropriate EPP error if the values provided by
the client can not be accepted for syntax or policy reasons.
Example Command for a Secure Delegation:
C:
C:
C:
C:
C:
C: example.com
C: 2
C:
C: ns1.example.com
C: ns2.example.com
C:
C: jd1234
C: sh8013
C: sh8013
C:
C: 2fooBAR
C:
C:
C:
C:
C:
C:
C: 12345
C: 3
C: 1
C: 49FD46E6C4B45C55D4AC
C:
C:
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C:
C: ABC-12345
C:
C:
Example Command for a Secure Delegation with OPTIONAL data:
C:
C:
C:
C:
C:
C: example.com
C: 2
C:
C: ns1.example.com
C: ns2.example.com
C:
C: jd1234
C: sh8013
C: sh8013
C:
C: 2fooBAR
C:
C:
C:
C:
C:
C:
C: 12345
C: 3
C: 1
C: 49FD46E6C4B45C55D4AC
C: 604800
C:
C: 256
C: 3
C: 1
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RFC 4310 EPP DNS Security Extensions Mapping November 2005
C: AQPJ////4Q==
C:
C:
C:
C:
C: ABC-12345
C:
C:
When a command has been processed successfully, the EPP
response is as described in the EPP domain mapping [2].
3.2.2. EPP Command
This extension does not add any elements to the EPP command
or response described in the EPP domain mapping [2].
3.2.3. EPP Command
This extension does not add any elements to the EPP command
or response described in the EPP domain mapping [2].
3.2.4. EPP Command
This extension does not add any elements to the EPP
command or response described in the EPP domain mapping
[2].
3.2.5. EPP Command
This extension defines additional elements for the EPP
command described in the EPP domain mapping [2]. No additional
elements are defined for the EPP response.
The EPP command provides a transform operation that allows a
client to modify the attributes of a domain object. In addition to
the EPP command elements described in the EPP domain mapping, the
command MUST contain an element. The element
MUST contain a child element that identifies the
extension namespace and the location of the extension schema. The
element contains a element to add
security information to a delegation, a element to
remove security information from a delegation, or a
element to replace security information with new security
information.
The element also contains an OPTIONAL "urgent"
attribute that a client can use to ask the server operator to
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complete and implement the update request with high priority. This
attribute accepts boolean values as described in Section 2.2; the
default value is boolean false. "High priority" is relative to
standard server operator policies that are determined using an
out-of-band mechanism.
The element is used to add DS information to an existing
set. The element MUST contain one or more elements as described in Section 3.1.2.
The element contains one or more
elements that are used to remove DS data from a delegation. The
element MUST contain a key tag value as described in
section 5.1.1 of RFC 4034 [6]. Removing all DS information can
remove the ability of the parent to secure the delegation to the
child zone.
The element is used to replace existing DS information
with new DS information. The element MUST contain one
or more elements as described in Section 3.1.2. The
data in these elements is used to replace whatever other data is
currently archived for the delegation.
The element contains an OPTIONAL "urgent" attribute.
In addition, the element contains OPTIONAL and elements. The server MUST abort
command processing and respond with an appropriate EPP error if the
values provided by the client can not be accepted for syntax or
policy reasons.
Example Command, Adding DS Data:
C:
C:
C:
C:
C:
C: example.com
C:
C:
C:
C:
C:
C:
C: 12346
C: 3
C: 1
C: 38EC35D5B3A34B44C39B
C:
C:
C:
C:
C: ABC-12345
C:
C:
Example Command, Removing DS Data:
C:
C:
C:
C:
C:
C: example.com
C:
C:
C:
C:
C:
C: 12345
C:
C:
C:
C: ABC-12345
C:
C:
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Example Urgent Command, Changing DS Data:
C:
C:
C:
C:
C:
C: example.com
C:
C:
C:
C:
C:
C:
C: 12345
C: 3
C: 1
C: 49FD46E6C4B45C55D4AC
C:
C:
C:
C:
C: ABC-12345
C:
C:
Example Command, Changing Data to Include OPTIONAL Data:
C:
C:
C:
C:
C:
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RFC 4310 EPP DNS Security Extensions Mapping November 2005
C: example.com
C:
C:
C:
C:
C:
C:
C: 12345
C: 3
C: 1
C: 49FD46E6C4B45C55D4AC
C: 604800
C:
C: 256
C: 3
C: 1
C: AQPJ////4Q==
C:
C:
C:
C:
C:
C: ABC-12345
C:
C:
When an extended command has been processed successfully,
the EPP response is as described in the EPP domain mapping [2]. A
server operator MUST return an EPP error result code of 2306 if an
urgent update (noted with an "urgent" attribute value of boolean
true) can not be completed with high priority.
4. Formal Syntax
An EPP object mapping is specified in XML Schema notation. The
formal syntax presented here is a complete schema representation of
the object mapping suitable for automated validation of EPP XML
instances. The BEGIN and END tags are not part of the schema; they
are used to note the beginning and ending of the schema for URI
registration purposes.
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RFC 4310 EPP DNS Security Extensions Mapping November 2005
BEGIN
Extensible Provisioning Protocol v1.0
domain name extension schema for provisioning
DNS security (DNSSEC) extensions.
END
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5. Internationalization Considerations
EPP is represented in XML, which provides native support for encoding
information using the Unicode character set and its more compact
representations including UTF-8 [14]. Conformant XML processors
recognize both UTF-8 and UTF-16 [15]. Though XML includes provisions
to identify and use other character encodings through use of an
"encoding" attribute in an declaration, use of UTF-8 is
RECOMMENDED in environments where parser encoding support
incompatibility exists.
As an extension of the EPP domain mapping [2], the elements, element
content, attributes, and attribute values described in this document
MUST inherit the internationalization conventions used to represent
higher-layer domain and core protocol structures present in an XML
instance that includes this extension.
6. IANA Considerations
This document uses URNs to describe XML namespaces and XML schemas
conforming to a registry mechanism described in RFC 3688 [10]. Two
URI assignments have been completed by the IANA.
Registration request for the extension namespace:
URI: urn:ietf:params:xml:ns:secDNS-1.0
Registrant Contact: IESG
XML: None. Namespace URIs do not represent an XML specification.
Registration request for the extension XML schema:
URI: urn:ietf:params:xml:schema:secDNS-1.0
Registrant Contact: IESG
XML: See the "Formal Syntax" section of this document.
7. Security Considerations
The mapping extensions described in this document do not provide any
security services beyond those described by EPP [1], the EPP domain
name mapping [2], and protocol layers used by EPP. The security
considerations described in these other specifications apply to this
specification as well.
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As with other domain object transforms, the EPP transform operations
described in this document MUST be restricted to the sponsoring
client as authenticated using the mechanisms described in sections
2.9.1.1 and 7 of RFC 3730 [1]. Any attempt to perform a transform
operation on a domain object by any client other than the sponsoring
client MUST be rejected with an appropriate EPP authorization error.
The provisioning service described in this document involves the
exchange of information that can have an operational impact on the
DNS. A trust relationship MUST exist between the EPP client and
server, and provisioning of public key information MUST only be done
after the identities of both parties have been confirmed using a
strong authentication mechanism.
An EPP client might be acting as an agent for a zone administrator
who wants to send delegation information to be signed and published
by the server operator. Man-in-the-middle attacks are thus possible
as a result of direct client activity or inadvertent client data
manipulation.
Acceptance of a false key by a server operator can produce
significant operational consequences. The child and parent zones
MUST be consistent to secure the delegation properly. In the absence
of consistent signatures, the delegation will not appear in the
secure name space, yielding untrustworthy query responses. If a key
is compromised, a client can either remove the compromised
information or update the delegation information via EPP commands
using the "urgent" attribute.
Operational scenarios requiring quick removal of a secure domain
delegation can be implemented using a two-step process. First,
security credentials can be removed using an "urgent" update as just
described. The domain can then be removed from the parent zone by
changing the status of the domain to either of the EPP "clientHold"
or "serverHold" domain status values. The domain can also be removed
from the zone using the EPP command, but this is a more
drastic step that needs to be considered carefully before use.
Data validity checking at the server requires computational
resources. A purposeful or inadvertent denial-of-service attack is
possible if a client requests some number of update operations that
exceed a server's processing capabilities. Server operators SHOULD
take steps to manage command load and command processing requirements
to minimize the risk of a denial-of-service attack.
The signature lifetime values provided by clients are requests that
can be rejected. Blind acceptance by a server operator can have an
adverse impact on a server's processing capabilities. Server
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operators SHOULD seriously consider adopting implementation rules to
limit the range of acceptable signature lifetime values to counter
potential adverse situations.
8. Acknowledgements
The author would like to thank the following people who have provided
significant contributions to the development of this document:
David Blacka, Olafur Gudmundsson, Mark Kosters, Ed Lewis, Dan Massey,
Marcos Sanz, Sam Weiler, and Ning Zhang.
9. References
9.1. Normative References
[1] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
RFC 3730, March 2004.
[2] Hollenbeck, S., "Extensible Provisioning Protocol (EPP) Domain
Name Mapping", RFC 3731, March 2004.
[3] Paoli, J., Sperberg-McQueen, C., Bray, T., and E. Maler,
"Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
FirstEdition REC-xml-20001006, October 2000.
[4] Maloney, M., Beech, D., Mendelsohn, N., and H. Thompson, "XML
Schema Part 1: Structures", W3C REC REC-xmlschema-1-20010502,
May 2001.
[5] Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes", W3C
REC REC-xmlschema-2-20010502, May 2001.
[6] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"Resource Records for the DNS Security Extensions", RFC 4034,
March 2005.
[7] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"Protocol Modifications for the DNS Security Extensions",
RFC 4035, March 2005.
[8] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[9] Kolkman, O., Schlyter, J., and E. Lewis, "Domain Name System
KEY (DNSKEY) Resource Record (RR) Secure Entry Point (SEP)
Flag", RFC 3757, April 2004.
Hollenbeck Standards Track [Page 20]
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[10] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
9.2. Informative References
[11] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[12] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[13] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"DNS Security Introduction and Requirements", RFC 4033,
March 2005.
[14] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
STD 63, RFC 3629, November 2003.
[15] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO 10646",
RFC 2781, February 2000.
Author's Address
Scott Hollenbeck
VeriSign, Inc.
21345 Ridgetop Circle
Dulles, VA 20166-6503
US
EMail: shollenbeck@verisign.com
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Full Copyright Statement
Copyright (C) The Internet Society (2005).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
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OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
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