< draft-ietf-jose-cfrg-curves-03.txt   draft-ietf-jose-cfrg-curves-06.txt >
Network Working Group I. Liusvaara Network Working Group I. Liusvaara
Internet-Draft Independent Internet-Draft Independent
Intended status: Standards Track July 1, 2016 Intended status: Standards Track August 18, 2016
Expires: January 2, 2017 Expires: February 19, 2017
CFRG ECDH and signatures in JOSE CFRG ECDH and signatures in JOSE
draft-ietf-jose-cfrg-curves-03 draft-ietf-jose-cfrg-curves-06
Abstract Abstract
This document defines how to use the Diffie-Hellman algorithms This document defines how to use the Diffie-Hellman algorithms
"X25519" and "X448" as well as the signature algorithms "Ed25519" and "X25519" and "X448" as well as the signature algorithms "Ed25519" and
"Ed448" from the IRTF CFRG elliptic curves work in JOSE. "Ed448" from the IRTF CFRG elliptic curves work in JOSE.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 1, line 32 skipping to change at page 1, line 32
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 2, 2017. This Internet-Draft will expire on February 19, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Terminology . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Key type "OKP" . . . . . . . . . . . . . . . . . . . . . . . 3 2. Key type "OKP" . . . . . . . . . . . . . . . . . . . . . . . 3
3. Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Signatures . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Signatures . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Algorithms . . . . . . . . . . . . . . . . . . . . . 3 3.1.1. Signing . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.2. Signing . . . . . . . . . . . . . . . . . . . . . . . 4 3.1.2. Verification . . . . . . . . . . . . . . . . . . . . 4
3.1.3. Verification . . . . . . . . . . . . . . . . . . . . 4
3.2. ECDH-ES . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. ECDH-ES . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2.1. Performing the ECDH Operation . . . . . . . . . . . . 4 3.2.1. Performing the ECDH Operation . . . . . . . . . . . . 5
4. Security considerations . . . . . . . . . . . . . . . . . . . 5 4. Security considerations . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8 7.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 8 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 8
A.1. Ed25519 Private Key . . . . . . . . . . . . . . . . . . . 8 A.1. Ed25519 Private Key . . . . . . . . . . . . . . . . . . . 8
A.2. Ed25519 Public Key . . . . . . . . . . . . . . . . . . . 8 A.2. Ed25519 Public Key . . . . . . . . . . . . . . . . . . . 9
A.3. JWK Thumbprint Canonicalization . . . . . . . . . . . . . 8 A.3. JWK Thumbprint Canonicalization . . . . . . . . . . . . . 9
A.4. Ed25519 Signing . . . . . . . . . . . . . . . . . . . . . 9 A.4. Ed25519 Signing . . . . . . . . . . . . . . . . . . . . . 9
A.5. Ed25519 Validation . . . . . . . . . . . . . . . . . . . 10 A.5. Ed25519 Validation . . . . . . . . . . . . . . . . . . . 10
A.6. ECDH-ES with X25519 . . . . . . . . . . . . . . . . . . . 10 A.6. ECDH-ES with X25519 . . . . . . . . . . . . . . . . . . . 11
A.7. ECDH-ES with X448 . . . . . . . . . . . . . . . . . . . . 11 A.7. ECDH-ES with X448 . . . . . . . . . . . . . . . . . . . . 12
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
Internet Research Task Force (IRTF) Crypto Forum Research Group Internet Research Task Force (IRTF) Crypto Forum Research Group
(CFRG) selected new Diffie-Hellman algorithms ("X25519" and "X448"; (CFRG) selected new Diffie-Hellman algorithms ("X25519" and "X448";
[RFC7748]) and signature algorithms ("Ed25519" and "Ed448"; [RFC7748]) and signature algorithms ("Ed25519" and "Ed448";
[I-D.irtf-cfrg-eddsa]) for asymmetric key cryptography. This [I-D.irtf-cfrg-eddsa]) for asymmetric key cryptography. This
document defines how those algorithms are to be used in JOSE in document defines how to use those algorithms in JOSE in interoperable
interoperable manner. manner.
This document defines the conventions to be used in the context of This document defines the conventions to use in the context of
[RFC7517] and [RFC7518]. [RFC7515], [RFC7516], and [RFC7517].
While the CFRG also defined two pairs of isogenous elliptic curves While the CFRG also defined two pairs of isogenous elliptic curves
that underlie these algorithms, these curves are not directly that underlie these algorithms, these curves are not directly
exposed, as the algorithms laid on top are sufficient for the exposed, as the algorithms laid on top are sufficient for the
purposes of JOSE and are much easier to use. (Trying to apply ECDSA purposes of JOSE and are much easier to use.
to those curves leads to nasty corner-cases and produces odd
results.)
All inputs to and outputs from the the ECDH and signature functions
are defined to be octet strings, with the exception of outputs of
verification function, which are booleans.
1.1. Requirements Terminology All inputs to and outputs from the ECDH and signature functions are
defined to be octet strings, with the exception of outputs of
verification functions, which are booleans.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
"JWS Signing Input" and "JWS Signature" are defined by [RFC7515].
"Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static"
is defined by [RFC7518], section 4.6.
The JOSE key format ("JSON Web Key (JWK)") is defined by [RFC7517]
and thumbprints for it ("JSON Web Key (JWK) Thumbprint") in
[RFC7638].
2. Key type "OKP" 2. Key type "OKP"
A new key type (kty) value "OKP" (Octet Key Pair) is defined for A new key type (kty) value "OKP" (Octet Key Pair) is defined for
public key algorithms that use octet strings as private and public public key algorithms that use octet strings as private and public
keys. It has the following parameters: keys. It has the following parameters:
o The parameter "kty" MUST be "OKP". o The parameter "kty" MUST be "OKP".
o The parameter "crv" MUST be present and contain the subtype of the o The parameter "crv" MUST be present and contain the subtype of the
key (from "JSON Web Elliptic Curve" registry). key (from the "JSON Web Elliptic Curve" registry).
o The parameter "x" MUST be present and contain the public key o The parameter "x" MUST be present and contain the public key
encoded using the base64url [RFC4648] encoding. encoded using the base64url [RFC4648] encoding.
o The parameter "d" MUST be present for private keys and contain the o The parameter "d" MUST be present for private keys and contain the
private key encoded using the base64url encoding. This parameter private key encoded using the base64url encoding. This parameter
MUST NOT be present for public keys. MUST NOT be present for public keys.
Note: Do not assume that there is an underlying elliptic curve, Note: Do not assume that there is an underlying elliptic curve,
despite the existence of the "crv" and "x" parameters. (For despite the existence of the "crv" and "x" parameters. (For
instance, this key type could be extended to represent DH algorithms instance, this key type could be extended to represent DH algorithms
based on hyperelliptic surfaces.) based on hyperelliptic surfaces.)
When calculating JWK Thumbprints [RFC7638], the three public key When calculating JWK Thumbprints [RFC7638], the three public key
fields are included in the hash input lexicographic order: "crv", fields are included in the hash input in lexicographic order: "crv",
"kty", and "x". "kty", and "x".
3. Algorithms 3. Algorithms
3.1. Signatures 3.1. Signatures
3.1.1. Algorithms For purpose of using EdDSA for signing data using "JSON Web Signature
(JWS)" ([RFC7515]), algorithm "EdDSA" is defined here, to be applied
For EdDSA signatures, algorithm "EdDSA" is defined here, to be as the value of the "alg" parameter.
applied as value of "alg" parameter.
The key type for these keys is "OKP" and key subtype for these keys The following key subtypes are defined here for use with EdDSA:
MUST be "Ed25519" for Ed25519 and "Ed448" for Ed448. The keys of
these subtypes MUST NOT be used for ECDH-ES.
"crv" EdDSA Variant "crv" EdDSA Variant
Ed25519 Ed25519 Ed25519 Ed25519
Ed448 Ed448 Ed448 Ed448
3.1.2. Signing The key type used with these keys is "OKP" and the algorithm used for
signing is "EdDSA". These subtypes MUST NOT be used for ECDH-ES.
The EdDSA variant used is determined by the subtype of the key
(Ed25519 for "Ed25519" and Ed448 for "Ed448").
3.1.1. Signing
Signing for these is preformed by applying the signing algorithm Signing for these is preformed by applying the signing algorithm
defined in [I-D.irtf-cfrg-eddsa] to the private key (as private key), defined in [I-D.irtf-cfrg-eddsa] to the private key (as private key),
public key (as public key) and the JWS Signing Input (as message). public key (as public key) and the JWS Signing Input (as message).
The resulting signature is the JWS Signature value. All inputs and The resulting signature is the JWS Signature. All inputs and outputs
outputs are octet strings. are octet strings.
3.1.3. Verification 3.1.2. Verification
Verification is performed by applying the verification algorithm Verification is performed by applying the verification algorithm
defined in [I-D.irtf-cfrg-eddsa] to the public key (as public key), defined in [I-D.irtf-cfrg-eddsa] to the public key (as public key),
the JWS Signing Input (as message) and the JWS Signature value (as the JWS Signing Input (as message) and the JWS Signature (as
signature). All inputs are octet strings. If the algorithm accepts, signature). All inputs are octet strings. If the algorithm accepts,
the signature is valid; otherwise, the signature is invalid. the signature is valid; otherwise, the signature is invalid.
3.2. ECDH-ES 3.2. ECDH-ES
The following key subtypes defined here for purpose of "Key Agreement The following key subtypes are defined here for purpose of "Key
with Elliptic Curve Diffie-Hellman Ephemeral Static" (ECDH-ES). Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static" (ECDH-
ES):
"crv" ECDH Function Applied "crv" ECDH Function Applied
X25519 X25519 X25519 X25519
X448 X448 X448 X448
The key type used with these keys is "OKP". These subtypes MUST NOT The key type used with these keys is "OKP". These subtypes MUST NOT
be used for signing. be used for signing.
[RFC7518] Section 4.6 defines the ECDH-ES algorithms "ECDH- [RFC7518] Section 4.6 defines the ECDH-ES algorithms "ECDH-
ES+A128KW", "ECDH-ES+A192KW", "ECDH-ES+A256KW" and "ECDH-ES". ES+A128KW", "ECDH-ES+A192KW", "ECDH-ES+A256KW" and "ECDH-ES".
skipping to change at page 6, line 5 skipping to change at page 6, line 14
The nominal security strengths of X25519 and X448 are ~126 and ~223 The nominal security strengths of X25519 and X448 are ~126 and ~223
bits. Therefore, using 256-bit symmetric encryption (especially key bits. Therefore, using 256-bit symmetric encryption (especially key
wrapping and encryption) with X448 is RECOMMENDED. wrapping and encryption) with X448 is RECOMMENDED.
5. Acknowledgements 5. Acknowledgements
Thanks to Michael B. Jones for his comments on an initial pre-draft Thanks to Michael B. Jones for his comments on an initial pre-draft
and editorial help. and editorial help.
Thanks to Matt Miller for some editorial help.
6. IANA considerations 6. IANA considerations
The following is added to the "JSON Web Key Types" registry: The following is added to the "JSON Web Key Types" registry:
o "kty" Parameter Value: "OKP" o "kty" Parameter Value: "OKP"
o Key Type Description: Octet string key pairs o Key Type Description: Octet string key pairs
o JOSE Implementation Requirements: Optional o JOSE Implementation Requirements: Optional
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 2 of [RFC-THIS] o Specification Document(s): Section 2 of [RFC-THIS]
skipping to change at page 7, line 44 skipping to change at page 8, line 5
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<http://www.rfc-editor.org/info/rfc4648>. <http://www.rfc-editor.org/info/rfc4648>.
[RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
for Security", RFC 7748, DOI 10.17487/RFC7748, January Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2016, <http://www.rfc-editor.org/info/rfc7748>. 2015, <http://www.rfc-editor.org/info/rfc7515>.
[I-D.irtf-cfrg-eddsa]
Josefsson, S. and I. Liusvaara, "Edwards-curve Digital
Signature Algorithm (EdDSA)", draft-irtf-cfrg-eddsa-05
(work in progress), March 2016.
7.2. Informative References
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517, [RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015, DOI 10.17487/RFC7517, May 2015,
<http://www.rfc-editor.org/info/rfc7517>. <http://www.rfc-editor.org/info/rfc7517>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, [RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015, DOI 10.17487/RFC7518, May 2015,
<http://www.rfc-editor.org/info/rfc7518>. <http://www.rfc-editor.org/info/rfc7518>.
[RFC7638] Jones, M. and N. Sakimura, "JSON Web Key (JWK) [RFC7638] Jones, M. and N. Sakimura, "JSON Web Key (JWK)
Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September
2015, <http://www.rfc-editor.org/info/rfc7638>. 2015, <http://www.rfc-editor.org/info/rfc7638>.
[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>.
[I-D.irtf-cfrg-eddsa]
Josefsson, S. and I. Liusvaara, "Edwards-curve Digital
Signature Algorithm (EdDSA)", draft-irtf-cfrg-eddsa-06
(work in progress), August 2016.
7.2. Informative References
[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
RFC 7516, DOI 10.17487/RFC7516, May 2015,
<http://www.rfc-editor.org/info/rfc7516>.
Appendix A. Examples Appendix A. Examples
To the extent possible, the examples use material taken from test To the extent possible, the examples use material taken from test
vectors of [RFC7748] and [I-D.irtf-cfrg-eddsa]. vectors of [RFC7748] and [I-D.irtf-cfrg-eddsa].
A.1. Ed25519 Private Key A.1. Ed25519 Private Key
{"kty":"OKP","crv":"Ed25519", {"kty":"OKP","crv":"Ed25519",
"d":"nWGxne_9WmC6hEr0kuwsxERJxWl7MmkZcDusAxyuf2A" "d":"nWGxne_9WmC6hEr0kuwsxERJxWl7MmkZcDusAxyuf2A"
"x":"11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo"} "x":"11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo"}
 End of changes. 27 change blocks. 
53 lines changed or deleted 73 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/