Internet DRAFT - draft-ietf-curdle-dnskey-ed25519
draft-ietf-curdle-dnskey-ed25519
Internet Engineering Task Force O. Sury
Internet-Draft CZ.NIC
Intended status: Standards Track R. Edmonds
Expires: August 19, 2016 Farsight Security, Inc.
February 16, 2016
Ed25519 for DNSSEC
draft-ietf-curdle-dnskey-ed25519-01
Abstract
This document describes how to specify Ed25519 keys and signatures in
DNS Security (DNSSEC). It uses the Edwards-curve Digital Security
Algorithm (EdDSA) with the Ed25519 parameter choice.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
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This Internet-Draft will expire on August 19, 2016.
Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. DNSKEY and RRSIG Resource Records for Ed25519 . . . . . . . . 3
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
DNSSEC, which is broadly defined in [RFC4033], [RFC4034], and
[RFC4035], uses cryptographic keys and digital signatures to provide
authentication of DNS data. Currently, the most popular signature
algorithm in use is RSA. [RFC5933] and [RFC6605] later defined the
use of GOST and NIST specified elliptic curve cryptography in DNSSEC.
This document defines the use of DNSSEC's DS, DNSKEY, and RRSIG
resource records (RRs) with a new signing algorithm, Edwards-curve
Digital Signature Algorithm (EdDSA) with the Ed25519 parameter
choice. A more thorough description of EdDSA and Ed25519 can be
found in [I-D.irtf-cfrg-eddsa].
Concerns about the real-world security of elliptic curve cryptography
have emerged since ECDSA was standardized for DNSSEC. The only two
curves standardized for use with ECDSA in DNSSEC, NIST P-256 and NIST
P-384, fail several of the [SafeCurves] security criteria and are
considered "unsafe". This document adds an additional elliptic curve
algorithm and parameter choice to DNSSEC, allowing additional
flexibility.
There are three main advantages of the EdDSA algorithm: It does not
require the use of a unique random number for each signature, there
are no padding or truncation issues as with ECDSA, and it is more
resilient to side-channel attacks.
Ed25519 has a 128-bit security target, which is considered to be
equivalent in strength to RSA with ~3000-bit keys. Ed25519 public
keys are 256 bits (32 bytes) long while signatures are 512 bits (64
bytes) long.
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The usage of elliptic curve cryptography in DNSSEC has advantages and
disadvantages relative to RSA as already described in [RFC6605].
Even when compared to the use of RSA at reduced relative strengths
(for instance, 1024- or 2048-bit RSA), Ed25519 still requires
substantially smaller keys and signatures. The authors of the study
Making the Case for Elliptic Curves in DNSSEC [ECCSIZE] came to the
conclusion that using elliptic curve cryptography rather than RSA in
DNSSEC can effectively prevent fragmentation of DNSSEC responses as
well as significantly reduce the amplification attack potential in
DNSSEC.
Signing with Ed25519 is significantly faster than signing with either
equivalently strong RSA or the two existing curves standardized for
use with the ECDSA algorithm in DNSSEC, while the validation of RSA
signatures is still significantly faster than the validation of
Ed25519 signatures. However, the authors of the TBD [ECCSPEED] study
came to the conclusion that even if the deployment of elliptic curve
cryptography in DNSSEC grows to cover 100% of the name space, a
resolver will still be able to perform validation using a single CPU
core.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. DNSKEY and RRSIG Resource Records for Ed25519
An Ed25519 public key consists of a 32-byte value, which is encoded
into the Public Key field of a DNSKEY resource record as a simple bit
string. The generation of a public key is defined in Chapter 5.1.5
in [I-D.irtf-cfrg-eddsa].
An Ed25519 signature consists of a 64-byte value, which is encoded
into the Signature field of an RRSIG resource record as a simple bit
string. The Ed25519 signature algorithm is described in Chapter
5.1.6 in [I-D.irtf-cfrg-eddsa].
The algorithm number associated with the use of Ed25519 in DS, DNSKEY
and RRSIG resource records is TBD. This registration is fully
defined in the IANA Considerations section.
4. Examples
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This section needs an update after the algorithm for Ed25519 is
assigned.
Private-key-format: v1.2
Algorithm: TBD (ED25519)
PrivateKey: ODIyNjAzODQ2MjgwODAxMjI2NDUxOTAyMDQxNDIyNjI=
# corresponding to 82260384628080122645190204142262 INT
example.com. 3600 IN DNSKEY 257 3 TBD (
l02Woi0iS8Aa25FQkUd9RMzZHJpBoRQwAQEX1SxZJA4= )
example.com. 3600 IN DS 3613 TBD 2 (
3aa5ab37efce57f737fc1627013fee07bdf241bd10f3
b1964ab55c78e79a304b )
www.example.com. 3600 IN A 192.0.2.1
www.example.com. 3600 IN RRSIG A TBD 3 3600 (
20150820000000 20150730000000 3613 example.com.
cvTRVrU7dwnemQuBq9/E4tlIiRpvWcEmYdzqs6SCQxw6
qmczBBQGldssMx1TCJnwsEs9ZuA2phPzuJNoon9BCA== )
Private-key-format: v1.2
Algorithm: TBD (ED25519)
PrivateKey: DSSF3o0s0f+ElWzj9E/Osxw8hLpk55chkmx0LYN5WiY=
example.com. 3600 IN DNSKEY 257 3 TBD (
zPnZ/QwEe7S8C5SPz2OfS5RR40ATk2/rYnE9xHIEijs= )
example.com. 3600 IN DS 55648 TBD 2 (
96401675bc7ecdd541ec0f70d69238c7b95d3bd4de1e
231a068ceb214d02a4ed )
www.example.com. 3600 IN A 192.0.2.1
www.example.com. 3600 IN RRSIG A TBD 3 3600 (
20150820000000 20150730000000 35452 example.com.
yuGb9rCNIuhDaRJbuhYHj89Y/3Pi8KWUm7lOt00ivVRGvgulmVX8DgpE
AFyMP2MKXJrqYJr+ViiCIDwcOIbPAQ==)
5. Acknowledgements
Some of the material in this document is copied liberally from
[RFC6605].
The authors of this document wish to thank Jan Vcelak, Pieter Lexis
and Kees Monshouwer for a review of this document.
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6. IANA Considerations
This document updates the IANA registry "Domain Name System Security
(DNSSEC) Algorithm Numbers". The following entry has been added to
the registry:
+--------------+---------------+
| Number | TBD |
| Description | Ed25519 |
| Mnemonic | ED25519 |
| Zone Signing | Y |
| Trans. Sec. | * |
| Reference | This document |
+--------------+---------------+
* There has been no determination of standardization of the use of
this algorithm with Transaction Security.
7. Implementation Status
(Note to the RFC Editor: please remove this entire section as well as
the reference to RFC 6982 before publication.)
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC6982].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC6982], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
TODO: Fill out this section.
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8. Security Considerations
The security level of Ed25519 is slightly under the standard 128-bit
level ([RFC7748]). Security considerations listed in [RFC7748] also
apply to the usage of Ed25519 in DNSSEC. Such an assessment could,
of course, change in the future if new attacks that work better than
the ones known today are found.
9. References
9.1. Normative References
[I-D.irtf-cfrg-eddsa]
Josefsson, S. and I. Liusvaara, "Edwards-curve Digital
Signature Algorithm (EdDSA)", draft-irtf-cfrg-eddsa-02
(work in progress), January 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[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,
<http://www.rfc-editor.org/info/rfc4033>.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, DOI 10.17487/RFC4034, March 2005,
<http://www.rfc-editor.org/info/rfc4034>.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
<http://www.rfc-editor.org/info/rfc4035>.
[RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
for Security", RFC 7748, DOI 10.17487/RFC7748, January
2016, <http://www.rfc-editor.org/info/rfc7748>.
9.2. Informative References
[ECCSIZE] van Rijswijk-Deij, R., Speroto, A., and A. Pras, "Making
the Case for Elliptic Curves in DNSSEC", 2015,
<http://www.sigcomm.org/ccr/papers/2015/
October/0000000.0000002>.
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[ECCSPEED]
van Rijswijk-Deij, R. and K. Hageman, "TBD", 2016, <TBD>.
[RFC5933] Dolmatov, V., Ed., Chuprina, A., and I. Ustinov, "Use of
GOST Signature Algorithms in DNSKEY and RRSIG Resource
Records for DNSSEC", RFC 5933, DOI 10.17487/RFC5933, July
2010, <http://www.rfc-editor.org/info/rfc5933>.
[RFC6605] Hoffman, P. and W. Wijngaards, "Elliptic Curve Digital
Signature Algorithm (DSA) for DNSSEC", RFC 6605,
DOI 10.17487/RFC6605, April 2012,
<http://www.rfc-editor.org/info/rfc6605>.
[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", RFC 6982,
DOI 10.17487/RFC6982, July 2013,
<http://www.rfc-editor.org/info/rfc6982>.
[SafeCurves]
Bernstein, D. and T. Lange, "SafeCurves: choosing safe
curves for elliptic-curve cryptography", 2016,
<http://safecurves.cr.yp.to/>.
Authors' Addresses
Ondrej Sury
CZ.NIC
Milesovska 1136/5
Praha 130 00
CZ
Phone: +420 222 745 111
Email: ondrej.sury@nic.cz
Robert Edmonds
Farsight Security, Inc.
177 Bovet Rd #180
San Mateo, California 94402
US
Phone: +1 650 489 7919
Email: edmonds@fsi.io
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