Network Working Group A. Milne
Internet-Draft
Intended status: Standards Track M. Blaser
Expires: September 23, 2007 D. Brown
E. Chin
Certicom Corp.
L. Dondeti
QUALCOMM, Inc.
March 22, 2007
ECC Algorithms for MIKEY
draft-ietf-msec-mikey-ecc-02
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Copyright (C) The IETF Trust (2007).
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Abstract
This document proposes extensions to the authentication, encryption
and digital signature methods described for use in MIKEY, employing
elliptic-curve cryptography (ECC). These extensions are defined to
align MIKEY with other ECC implementations and standards.
It should be noted that this document is not self-contained; it uses
the notations and definitions of [RFC3830].
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. MIKEY-DHSIGN with ECDSA or ECGDSA . . . . . . . . . . . . . . 5
3. MIKEY-DHSIGN with ECDH . . . . . . . . . . . . . . . . . . . . 6
4. MIKEY-ECIES . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. MIKEY-ECMQV . . . . . . . . . . . . . . . . . . . . . . . . . 10
6. Additional Payload Encoding . . . . . . . . . . . . . . . . . 11
6.1. ECC Point payload (ECCPT) . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
Intellectual Property and Copyright Statements . . . . . . . . . . 18
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1. Introduction
This document describes additional algorithms for use in MIKEY. The
document assumes that the reader is familiar with the MIKEY protocol.
The MIKEY protocol [RFC3830] defines three methods for transporting
or establishing keys: with the use of a pre-shared key, public-key
encryption (MIKEY-RSA), and Diffie-Hellman (DH) key exchange (MIKEY-
DHSIGN). This document extends MIKEY-DHSIGN to use Elliptic Curve
Digital Signature Algorithm (ECDSA) or Elliptic Curve German Digital
Signature Algorithm (ECGDSA) as the signature algorithm and further
extends MIKEY-DHSIGN to use Elliptic Curve Diffie-Hellman (ECDH)
groups. In addition, this document introduces two new methods based
on the the Elliptic Curve Integrated Encryption Scheme (ECIES) and
Elliptic Curve Menezes-Qu-Vanstone (ECMQV) in exchanges similar to
those of MIKEY-RSA, and name these methods MIKEY-ECIES and MIKEY-
ECMQV respectively.
Implementations have shown that elliptic curve algorithms can
significantly improve performance and security-per-bit over other
recommended algorithms. The purpose of this document is to expand
the options available to implementers of MIKEY to take advantage of
these benefits.
In addition, elliptic curve algorithms are capable of providing
security consistent with AES keys of 128, 192, and 256 bits without
extensive growth in asymmetric key sizes. The following table, taken
from [HOF] and [LEN], gives approximate comparable key sizes for
symmetric systems, ECC systems, and DH/DSA/RSA systems. The
estimates are based on the running times of the best algorithms known
today.
Symmetric | ECC2N | ECP | DH/DSA/RSA
80 | 163 | 192 | 1024
128 | 283 | 256 | 3072
192 | 409 | 384 | 7680
256 | 571 | 521 | 15360
Table 1: Comparable key sizes
Thus, for example, when securing a 192-bit symmetric key, it is
prudent to use either 409-bit ECC2N, 384-bit ECP, or 7680-bit DH/DSA/
RSA. With smaller key sizes the symmetric keys would be
underprotected.
Section 2 describes the extension of MIKEY-DHSIGN to use the ECDSA or
ECGDSA signature algorithm. Section 3 describes the extension of
MIKEY-DHSIGN to use ECDH groups. Section 4 describes the MIKEY-ECIES
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method. Section 5 describes the MIKEY-ECMQV method. Section 6
describes additional payloads required to support these new methods.
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].
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2. MIKEY-DHSIGN with ECDSA or ECGDSA
MIKEY-DHSIGN is described in Section 3.3 of [RFC3830]. The
Initiator's message includes SIGNi, a signature covering the
Initiator's message. As well, the Responder's message includes
SIGNr, a signature covering the Responder's message. According to
Section 4.2.6 of [RFC3830], the signature algorithm applied is
defined by, and dependent on the certificate used. It is MANDATORY
to support RSA PKCS#1, v1.5, and it is RECOMMENDED to support RSA
PSS. Instead of these signature algorithms, ECDSA or ECGDSA may be
used to allow shorter and more efficient signatures.
ECDSA signatures are detailed in [ANSI-X9.62] and ECGDSA signatures
are detailed in [ISO-IEC-15946-2]. Curve selection and other
parameters will be defined by, and dependent on the certificate used.
When generating signatures, the hash function that MUST be used
depends on the key size, as follows:
ECC2N | ECP | Hash To Use
163 | 192 | SHA-1
233 | 224 | SHA-224
283 | 256 | SHA-256
409 | 384 | SHA-384
571 | 521 | SHA-512
Table 2: Hash to use with ECDSA and ECGDSA
The signature payload (SIGN) specified in Section 6.5 of [RFC3830]
can be used without modification. Two additional S types for ECDSA
and ECGDSA is defined as follows:
S type | Value | Comments
-------------------------------------
ECDSA | 2 | ECDSA signature [ANSI_X9.62]
ECGDSA | 3 | ECGDSA signature [ISO/IEC_15946-2]
[RFC3279] describes algorithms and identifiers for Internet X.509
certificates and CRLs. It includes ECC algorithms and identifiers.
To use the ECDSA or ECGDSA signature algorithm with Elliptic Curve
Diffie-Hellman, this extension to MIKEY-DHSIGN may be combined with
the extension described in Section 3.
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3. MIKEY-DHSIGN with ECDH
MIKEY-DHSIGN is described in Section 3.3 of [RFC3830]. According to
Section 4.2.7 of [RFC3830], the support for OAKLEY 5 is MANDATORY and
support for OAKLEY 1 and OAKLEY 2 is OPTIONAL. Instead of these
Diffie-Hellman (DH) groups, elliptic curve Diffie-Hellman (ECDH)
groups may significantly improve performance and security.
The ECDH groups to be used by MIKEY are the groups recommended by
NIST in FIPS 186-2 [FIPS-186-2]. Detailed descriptions of the ECDH
groups can be found in each of FIPS 186-2 [FIPS-186-2] and SEC 2
[SEC2]. The ECDH groups use elliptic curves over GF[2^N] with N
prime or over GF[P] with P prime. Eleven of the groups proposed here
have been assigned identifiers by IANA [IANA] and the remaining five
might later be assigned identifiers by IANA. The group with IANA
number 6 is described in [ANSI-X9.62] and [SEC2], with object
identifier sect163r1, but it is not one of the fifteen curves that
NIST recommends [FIPS-186-2]. The remaining NIST recommended groups
are suggested and anticipated to be assigned IANA numbers as
specified in Table 3.
id Group Type Group Description NIST Name SEC 2 OID
-- ---------- ----------------- --------- ---------
22 2 ECP ECPRGF192Random P-192 secp192r1
23 3 EC2N EC2NGF163Random B-163 sect163r2
7 3 EC2N EC2NGF163Koblitz K-163 sect163k1
6 3 EC2N EC2NGF163Random2 none sect163r1
24 2 ECP ECPRGF224Random P-224 secp224r1
25 3 EC2N EC2NGF233Random B-233 sect233r1
26 3 EC2N EC2NGF233Koblitz K-233 sect233k1
19 2 ECP ECPRGF256Random P-256 secp256r1
8 3 EC2N EC2NGF283Random B-283 sect283r1
9 3 EC2N EC2NGF283Koblitz K-283 sect283k1
20 2 ECP ECPRGF384Random P-384 secp384r1
10 3 EC2N EC2NGF409Random B-409 sect409r1
11 3 EC2N EC2NGF409Koblitz K-409 sect409k1
21 2 ECP ECPRGF521Random P-521 secp521r1
12 3 EC2N EC2NGF571Random B-571 sect571r1
13 3 EC2N EC2NGF571Koblitz K-571 sect571k1
Table 3: Recommended Groups and Names
The ECDH groups in Table 3 are arranged into 5 classes, corresponding
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to approximately equivalent security strengths. To encourage
interoperability, implementations that support one of these classes,
SHOULD support the one group in that class that is defined over a
prime field (which will be one of P-192, P-224, P-256, P-384, or
P-521). Implementations SHOULD support one of P-256 or P-384.
Implementations MAY support any set of groups.
The DH data payload (DH) specified in Section 6.4 of [RFC3830] can be
used without modification. Additional DH-Group identifiers are
required as follows:
DH-Group | Value
--------------------------------------|-------
ECPRGF192Random / P-192 / secp192r1 | 3
EC2NGF163Random / B-163 / sect163r2 | 4
EC2NGF163Koblitz / K-163 / sect163k1 | 5
EC2NGF163Random2 / none / sect163r1 | 6
|
ECPRGF224Random / P-224 / secp224r1 | 7
EC2NGF233Random / B-233 / sect233r1 | 8
EC2NGF233Koblitz / K-233 / sect233k1 | 9
|
ECPRGF256Random / P-256 / secp256r1 | 10
EC2NGF283Random / B-283 / sect283r1 | 11
EC2NGF283Koblitz / K-283 / sect283k1 | 12
|
ECPRGF384Random / P-384 / secp384r1 | 13
EC2NGF409Random / B-409 / sect409r1 | 14
EC2NGF409Koblitz / K-409 / sect409k1 | 15
|
ECPRGF521Random / P-521 / secp521r1 | 16
EC2NGF571Random / B-571 / sect571r1 | 17
EC2NGF571Koblitz / K-571 / sect571k1 | 18
When using the ECDH groups, the DH-value in the DH data payload (DH)
is the octet string representation specified in ANSI X9.62
[ANSI-X9.62] and [SEC1].
If the initiator chooses secret i and the responder chooses secret r,
then the raw shared secret is the x-coordinate(only) of (ir)*G.
To use ECDH and ECDSA signature algorithm or to use ECDH and ECGDSA
signature algorithm, this extension to MIKEY-DHSIGN may be combined
with the extension described in Section 2.
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4. MIKEY-ECIES
The Elliptic Curve Integrated Encryption Scheme (ECIES) is a public-
key encryption scheme based on ECC. Section 3.2 of [RFC3830] already
specifies a public-key encryption method (MIKEY-RSA). Here we
describe the new MIKEY-ECIES method.
Initiator Responder
I_MESSAGE =
HDR, T, RAND, [IDi|CERTi], [IDr], {SP},
ECCPT, KEMAC, [CHASH], SIGNi --->
R_MESSAGE =
[<---] HDR, T, [IDr], V
As with the MIKEY-RSA case, the main objective of the Initiator's
message is to transport one or more TGKs and a set of security
parameters to the Responder in a secure manner.
With MIKEY-RSA, the TGKs are encrypted with an "envelope key".
However, ECIES uses a symmetric encapsulation algorithm, so
encrypting an envelope key (to be used with another symmetric method
to decrypt the actual payload) would be redundant. As a result, the
PKE payload is not used.
The ECCPT contains the elliptic curve point that represents the
ephemeral public key required for ECIES.
As in MIKEY-RSA, the KEMAC contains a set of encrypted sub-payloads
and a MAC:
KEMAC = E(encr_key, IDi || {TGK}) || MAC
The encr_key and auth_key are derived from the ECIES-derived key by
using the algorithm described in Section 4.1.4 of [RFC3830], in
identical fashion as the envelope key used in the MIKEY-RSA.
Both SIGNi and SIGNr will use either ECDSA or ECGDSA as a signature
algorithm, as described in Section 2.
As in MIKEY-RSA, it is possible to cache the ECIES-derived key, so
that it can be used as a pre-shared key.
ECIES is described in detail in [SEC1]. For ECIES, the key
derivation function that MUST be used is ANSI-X9.63-KDF as described
in [SEC1]. As well, the MAC scheme that MUST be used is HMAC-SHA-1-
160. The 'standard' elliptic curve Diffie-Hellman primitive MUST be
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used (as opposed to 'cofactor'). The symmetric encryption scheme
that MUST be used depends on the key size, as follows:
ECC2N | ECP | Symmetric Cipher To Use
163 | 192 | 3DES-CBC
233 | 224 | AES-128-CBC
283 | 256 | AES-128-CBC
409 | 384 | AES-256-CBC
571 | 521 | AES-256-CBC
Table 4: Symmetric cipher to use with ECIES
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5. MIKEY-ECMQV
ECMQV (Elliptic Curve Menezes-Qu-Vanstone) is a 3-pass or 1-pass
protocol that has been standardized in ANSI X9.63 [ANSI-X9.63]. Both
modes of ECMQV provide mutual authentication between the
communicating parties and key establishment for the secure transport
of data. Here we describe the new MIKEY-ECMQV method based on the
1-pass protocol.
Initiator Responder
I_MESSAGE =
HDR, T, RAND, [IDi|CERTi], [IDr], {SP},
ECCPT, KEMAC, [CHASH], SIGNi --->
R_MESSAGE =
[<---] HDR, T, [IDr], V
The ECCPT contains the elliptic curve point that represents the
ephemeral public key contributed by the Initiator.
As in MIKEY-RSA, the KEMAC contains a set of encrypted sub-payloads
and a MAC:
KEMAC = E(encr_key, IDi || {TGK}) || MAC
The encr_key and auth_key are derived from the ECMQV-derived key by
using the algorithm described in Section 4.1.4 of [RFC3830], in
identical fashion as the envelope key used in the MIKEY-RSA.
1-pass ECMQV is described in detail in ANSI X9.63 [ANSI-X9.63].
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6. Additional Payload Encoding
6.1. ECC Point payload (ECCPT)
The ECCPT payload carries a point on the elliptic curve used in
MIKEY-ECIES and MIKEY-ECMQV. The payload identifier is 22.
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next payload ! Point length ! Pt data ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Point data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Next payload (8 bits): identifies the payload that is added after
this payload. See Section 6.1 for values.
* Point length (16 bits): length of the Point data field (in *bits*).
* Point data (variable length): point data, padded to end on a 32-bit
boundary, encoded in octet string representation specified in
ANSI X9.62 [ANSI-X9.62] and [SEC1]. Uncompressed format MUST be
supported. Hybrid and compressed formats MAY be supported.
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7. Security Considerations
Since this document proposes new methods for use within MIKEY, many
of the security considerations contained within [RFC3830] apply here
as well. Some of the methods proposed in this document offer higher
cryptographic strength than those proposed in [RFC3830]. In
particular, there are elliptic curves corresponding to each of the
symmetric key sizes 80 bits, 128 bits, 192 bits, and 256 bits. This
allows the MIKEY key exchange to offer security comparable with
higher-strength AES algorithms and SHA implementations. The methods
proposed in this document are among those standardized by NIST in
FIPS 186-2 [FIPS-186-2], by the SECG in SEC2 [SEC2], and by ANSI in
ANSI X9.62 [ANSI-X9.62] and X9.63 [ANSI-X9.63].
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8. IANA Considerations
This document adds entries to existing MIKEY namespaces in Section 2
(S types in signature payloads), Section 3 (DH Group identifier in DH
payloads), and Section 6.1 (ECCPT payload identifier).
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9. References
9.1. Normative References
[ANSI-X9.62]
American National Standards Institute, "ANSI X9.62: Public
Key Cryptography For The Financial Services Industry: The
Elliptic Curve Digital Signature Algorithm (ECDSA)", 2005.
[ANSI-X9.63]
American National Standards Institute, "ANSI X9.63: Public
Key Cryptography For The Financial Services Industry: Key
Agreement and Key Transport using Elliptic Curve
Cryptography", 2001.
[FIPS-186-2]
National Institute of Standards and Technology, "FIPS
186-2 Digital Signature Standard", 2000.
[IANA] Internet Assigned Numbers Authority, "Attribute Assigned
Numbers.", <http://www.isi.edu/in-notes/iana/assignments/
ipsec-registry>.
[ISO-IEC-15946-2]
International Organization for Standardization and
International Electrotechnical Commission, "ISO/IEC
15946-2: Information technology -- Security techniques --
Cryptographic techniques based on elliptic curves -- Part
2: Digital signatures", 2002.
[RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and
Identifiers for the Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 3279, April 2002.
[RFC3830] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K.
Norrman, "MIKEY: Multimedia Internet KEYing", RFC 3830,
August 2004.
[SEC1] Standards for Efficient Crytopgraphy Group, "Elliptic
Curve Cryptography", September 2000.
[SEC2] Standards for Efficient Crytopgraphy Group, "Recommended
Elliptic Curve Domain Parameters", September 2000.
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9.2. Informative References
[HOF] Hoffman, P. and H. Orman, "Determining strengths for
public keys used for exchanging symmetric keys",
August 2000.
[LEN] Lenstra, A. and E. Verhuel, "Selecting cryptographic key
sizes", <http://www.cryptosavvy.com>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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Authors' Addresses
Andrew Milne
Mitch Blaser
Certicom Corp.
5520 Explorer Drive
Mississauga, Ontario L4W 5L1
CANADA
Phone: +1-905-507-4220
Fax: +1-905-507-4230
Email: mblaser@certicom.com
URI: http://www.certicom.com
Daniel R. L. Brown
Certicom Corp.
5520 Explorer Drive
Mississauga, Ontario L4W 5L1
CANADA
Phone: +1-905-507-4220
Fax: +1-905-507-4230
Email: dbrown@certicom.com
URI: http://www.certicom.com
Eugene Chin
Certicom Corp.
5520 Explorer Drive
Mississauga, Ontario L4W 5L1
CANADA
Phone: +1-905-507-4220
Fax: +1-905-507-4230
Email: echin@certicom.com
URI: http://www.certicom.com
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Lakshminath Dondeti
QUALCOMM, Inc.
5775 Morehouse Drive
San Diego, CA
USA
Phone: +1-858-845-1267
Email: ldondeti@qualcomm.com
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