Network Working Group S. Blake-Wilson

Network Working Group S. Blake-Wilson
Request for Comments: 3278 D. Brown
Category: Informational Certicom Corp
P. Lambert
Cosine Communications
April 2002

Use of Elliptic Curve Cryptography (ECC) Algorithms
in Cryptographic Message Syntax (CMS)

Status of this Memo

This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2002). All Rights Reserved.

Abstract

This document describes how to use Elliptic Curve Cryptography (ECC)
public-key algorithms in the Cryptographic Message Syntax (CMS). The
ECC algorithms support the creation of digital signatures and the
exchange of keys to encrypt or authenticate content. The definition
of the algorithm processing is based on the ANSI X9.62 standard,
developed by the ANSI X9F1 working group, the IEEE 1363 standard, and
the SEC 1 standard.

The readers attention is called to the Intellectual Property Rights
section at the end of this document.

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Table of Contents

1 Introduction ................................................... 2
1.1 Requirements terminology .................................. 3
2 SignedData using ECC .......................................... 3
2.1 SignedData using ECDSA ................................... 3
2.1.1 Fields of the SignedData .......................... 3
2.1.2 Actions of the sending agent ...................... 4
2.1.3 Actions of the receiving agent .................... 4
3 EnvelopedData using ECC ....................................... 4
3.1 EnvelopedData using ECDH ................................. 5
3.1.1 Fields of KeyAgreeRecipientInfo ................... 5
3.1.2 Actions of the sending agent ...................... 5
3.1.3 Actions of the receiving agent .................... 6
3.2 EnvelopedData using 1-Pass ECMQV ......................... 6
3.2.1 Fields of KeyAgreeRecipientInfo ................... 6
3.2.2 Actions of the sending agent ...................... 7
3.2.3 Actions of the receiving agent .................... 7
4 AuthenticatedData using ECC ............ ...................... 8
4.1 AuthenticatedData using 1-pass ECMQV ..................... 8
4.1.1 Fields of KeyAgreeRecipientInfo ................... 8
4.1.2 Actions of the sending agent ...................... 8
4.1.3 Actions of the receiving agent .................... 8
5 Recommended Algorithms and Elliptic Curves .................... 9
6 Certificates using ECC ........................................ 9
7 SMIMECapabilities Attribute and ECC ........................... 9
8 ASN.1 Syntax .................................................. 10
8.1 Algorithm identifiers .................................... 10
8.2 Other syntax ............................................. 11
9 Summary ....................................................... 12
References ....................................................... 13
Security Considerations .......................................... 14
Intellectual Property Rights ..................................... 14
Acknowledgments .................................................. 15
Authors' Addresses ............................................... 15
Full Copyright Statement ......................................... 16

1 Introduction

The Cryptographic Message Syntax (CMS) is cryptographic algorithm
independent. This specification defines a profile for the use of
Elliptic Curve Cryptography (ECC) public key algorithms in the CMS.
The ECC algorithms are incorporated into the following CMS content
types:

- 'SignedData' to support ECC-based digital signature methods
(ECDSA) to sign content

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- 'EnvelopedData' to support ECC-based public-key agreement
methods (ECDH and ECMQV) to generate pairwise key-encryption
keys to encrypt content-encryption keys used for content
encryption

- 'AuthenticatedData' to support ECC-based public-key agreement
methods (ECMQV) to generate pairwise key-encryption keys to
encrypt MAC keys used for content authentication and integrity

Certification of EC public keys is also described to provide public-
key distribution in support of the specified techniques.

1.1 Requirements terminology

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
[MUST].

2 SignedData using ECC

This section describes how to use ECC algorithms with the CMS
SignedData format to sign data.

2.1 SignedData using ECDSA

This section describes how to use the Elliptic Curve Digital
Signature Algorithm (ECDSA) with SignedData. ECDSA is specified in
[X9.62]. The method is the elliptic curve analog of the Digital
Signature Algorithm (DSA) [FIPS 186-2].

In an implementation that uses ECDSA with CMS SignedData, the
following techniques and formats MUST be used.

2.1.1 Fields of the SignedData

When using ECDSA with SignedData, the fields of SignerInfo are as in
[CMS], but with the following restrictions:

digestAlgorithm MUST contain the algorithm identifier sha-1 (see
Section 8.1) which identifies the SHA-1 hash algorithm.

signatureAlgorithm contains the algorithm identifier ecdsa-with-
SHA1 (see Section 8.1) which identifies the ECDSA signature
algorithm.

signature MUST contain the DER encoding (as an octet string) of a
value of the ASN.1 type ECDSA-Sig-Value (see Section 8.2).

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When using ECDSA, the SignedData certificates field MAY include the
certificate(s) for the EC public key(s) used in the generation of the
ECDSA signatures in SignedData. ECC certificates are discussed in
Section 6.

2.1.2 Actions of the sending agent

When using ECDSA with SignedData, the sending agent uses the message
digest calculation process and signature generation process for
SignedData that are specified in [CMS]. To sign data, the sending
agent uses the signature method specified in [X9.62, Section 5.3]
with the following exceptions:

- In [X9.62, Section 5.3.1], the integer "e" is instead
determined by converting the message digest generated according
to [CMS, Section 5.4] to an integer using the data conversion
method in [X9.62, Section 4.3.2].

The sending agent encodes the resulting signature using the ECDSA-
Sig-Value syntax (see Section 8.2) and places it in the SignerInfo
signature field.

2.1.3 Actions of the receiving agent

When using ECDSA with SignedData, the receiving agent uses the
message digest calculation process and signature verification process
for SignedData that are specified in [CMS]. To verify SignedData,
the receiving agent uses the signature verification method specified
in [X9.62, Section 5.4] with the following exceptions:

- In [X9.62, Section 5.4.1] the integer "e'" is instead
determined by converting the message digest generated according
to [CMS, Section 5.4] to an integer using the data conversion
method in [X9.62, Section 4.3.2].

In order to verify the signature, the receiving agent retrieves the
integers r and s from the SignerInfo signature field of the received
message.

3 EnvelopedData using ECC Algorithms

This section describes how to use ECC algorithms with the CMS
EnvelopedData format.

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3.1 EnvelopedData using (ephemeral-static) ECDH

This section describes how to use the ephemeral-static Elliptic Curve
Diffie-Hellman (ECDH) key agreement algorithm with EnvelopedData.
Ephemeral-static ECDH is specified in [SEC1] and [IEEE1363].
Ephemeral-static ECDH is the the elliptic curve analog of the
ephemeral-static Diffie-Hellman key agreement algorithm specified
jointly in the documents [CMS, Section 12.3.1.1] and [CMS-DH].

In an implementation that uses ECDH with CMS EnvelopedData with key
agreement, the following techniques and formats MUST be used.

3.1.1 Fields of KeyAgreeRecipientInfo

When using ephemeral-static ECDH with EnvelopedData, the fields of
KeyAgreeRecipientInfo are as in [CMS], but with the following
restrictions:

originator MUST be the alternative originatorKey. The
originatorKey algorithm field MUST contain the id-ecPublicKey
object identifier (see Section 8.1) with NULL parameters. The
originatorKey publicKey field MUST contain the DER-encoding of a
value of the ASN.1 type ECPoint (see Section 8.2), which
represents the sending agent's ephemeral EC public key.

keyEncryptionAlgorithm MUST contain the dhSinglePass-stdDH-
sha1kdf-scheme object identifier (see Section 8.1) if standard
ECDH primitive is used, or the dhSinglePass-cofactorDH-sha1kdf-
scheme object identifier (see Section 8.1) if the cofactor ECDH
primitive is used. The parameters field contains
KeyWrapAlgorithm. The KeyWrapAlgorithm is the algorithm
identifier that indicates the symmetric encryption algorithm used
to encrypt the content-encryption key (CEK) with the key-
encryption key (KEK).

3.1.2 Actions of the sending agent

When using ephemeral-static ECDH with EnvelopedData, the sending
agent first obtains the recipient's EC public key and domain
parameters (e.g. from the recipient's certificate). The sending
agent then determines an integer "keydatalen", which is the
KeyWrapAlgorithm symmetric key-size in bits, and also a bit string
"SharedInfo", which is the DER encoding of ECC-CMS-SharedInfo (see
Section 8.2). The sending agent then performs the key deployment and
the key agreement operation of the Elliptic Curve Diffie-Hellman
Scheme specified in [SEC1, Section 6.1]. As a result the sending
agent obtains:

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- an ephemeral public key, which is represented as a value of the
type ECPoint (see Section 8.2), encapsulated in a bit string
and placed in the KeyAgreeRecipientInfo originator field, and

- a shared secret bit string "K", which is used as the pairwise
key-encryption key for that recipient, as specified in [CMS].

3.1.3 Actions of the receiving agent

When using ephemeral-static ECDH with EnvelopedData, the receiving
agent determines the bit string "SharedInfo", which is the DER
encoding of ECC-CMS-SharedInfo (see Section 8.2), and the integer
"keydatalen" from the key-size, in bits, of the KeyWrapAlgorithm.
The receiving agent retrieves the ephemeral EC public key from the
bit string KeyAgreeRecipientInfo originator, with a value of the type
ECPoint (see Section 8.2) encapsulated as a bit string. The
receiving agent performs the key agreement operation of the Elliptic
Curve Diffie-Hellman Scheme specified in [SEC1, Section 6.1]. As a
result, the receiving agent obtains a shared secret bit string "K",
which is used as the pairwise key-encryption key to unwrap the CEK.

3.2 EnvelopedData using 1-Pass ECMQV

This section describes how to use the 1-Pass elliptic curve MQV
(ECMQV) key agreement algorithm with EnvelopedData. ECMQV is
specified in [SEC1] and [IEEE1363]. Like the KEA algorithm [CMS-
KEA], 1-Pass ECMQV uses three key pairs: an ephemeral key pair, a
static key pair of the sending agent, and a static key pair of the
receiving agent. An advantage of using 1-Pass ECMQV is that it can
be used with both EnvelopedData and AuthenticatedData.

In an implementation that uses 1-Pass ECMQV with CMS EnvelopedData
with key agreement, the following techniques and formats MUST be
used.

3.2.1 Fields of KeyAgreeRecipientInfo

When using 1-Pass ECMQV with EnvelopedData, the fields of
KeyAgreeRecipientInfo are:

originator identifies the static EC public key of the sender. It
SHOULD be one of the alternatives, issuerAndSerialNumber or
subjectKeyIdentifier, and point to one of the sending agent's
certificates.

ukm MUST be present. The ukm field MUST contain an octet string
which is the DER encoding of the type MQVuserKeyingMaterial (see
Section 8.2). The MQVuserKeyingMaterial ephemeralPublicKey

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algorithm field MUST contain the id-ecPublicKey object identifier
(see Section 8.1) with NULL parameters field. The
MQVuserKeyingMaterial ephemeralPublicKey publicKey field MUST
contain the DER-encoding of the ASN.1 type ECPoint (see Section
8.2) representing sending agent's ephemeral EC public key. The
MQVuserKeyingMaterial addedukm field, if present, SHOULD contain
an octet string of additional user keying material of the sending
agent.

keyEncryptionAlgorithm MUST be the mqvSinglePass-sha1kdf-scheme
algorithm identifier (see Section 8.1), with the parameters field
KeyWrapAlgorithm. The KeyWrapAlgorithm indicates the symmetric
encryption algorithm used to encrypt the CEK with the KEK
generated using the 1-Pass ECMQV algorithm.

3.2.2 Actions of the sending agent

When using 1-Pass ECMQV with EnvelopedData, the sending agent first
obtains the recipient's EC public key and domain parameters, (e.g.
from the recipient's certificate) and checks that the domain
parameters are the same. The sending agent then determines an
integer "keydatalen", which is the KeyWrapAlgorithm symmetric key-
size in bits, and also a bit string "SharedInfo", which is the DER
encoding of ECC-CMS-SharedInfo (see Section 8.2). The sending agent
then performs the key deployment and key agreement operations of the
Elliptic Curve MQV Scheme specified in [SEC1, Section 6.2]. As a
result, the sending agent obtains:

- an ephemeral public key, which is represented as a value of
type ECPoint (see Section 8.2), encapsulated in a bit string,
placed in an MQVuserKeyingMaterial ephemeralPublicKey publicKey
field (see Section 8.2), and

- a shared secret bit string "K", which is used as the pairwise
key-encryption key for that recipient, as specified in [CMS].

The ephemeral public key can be re-used with an AuthenticatedData for
greater efficiency.

3.2.3 Actions of the receiving agent

When using 1-Pass ECMQV with EnvelopedData, the receiving agent
determines the bit string "SharedInfo", which is the DER encoding of
ECC-CMS-SharedInfo (see Section 8.2), and the integer "keydatalen"
from the key-size, in bits, of the KeyWrapAlgorithm. The receiving
agent then retrieves the static and ephemeral EC public keys of the
originator, from the originator and ukm fields as described in
Section 3.2.1, and its static EC public key identified in the rid

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field and checks that the domain parameters are the same. The
receiving agent then performs the key agreement operation of the
Elliptic Curve MQV Scheme [SEC1, Section 6.2]. As a result, the
receiving agent obtains a shared secret bit string "K" which is used
as the pairwise key-encryption key to unwrap the CEK.

4 AuthenticatedData using ECC

This section describes how to use ECC algorithms with the CMS
AuthenticatedData format. AuthenticatedData lacks non-repudiation,
and so in some instances is preferable to SignedData. (For example,
the sending agent might not want the message to be authenticated when
forwarded.)

4.1 AuthenticatedData using 1-pass ECMQV

This section describes how to use the 1-Pass elliptic curve MQV
(ECMQV) key agreement algorithm with AuthenticatedData. ECMQV is
specified in [SEC1]. An advantage of using 1-Pass ECMQV is that it
can be used with both EnvelopedData and AuthenticatedData.

4.1.1 Fields of the KeyAgreeRecipientInfo

The AuthenticatedData KeyAgreeRecipientInfo fields are used in the
same manner as the fields for the corresponding EnvelopedData
KeyAgreeRecipientInfo fields of Section 3.2.1 of this document.

4.1.2 Actions of the sending agent

The sending agent uses the same actions as for EnvelopedData with 1-
Pass ECMQV, as specified in Section 3.2.2 of this document.

The ephemeral public key can be re-used with an EnvelopedData for
greater efficiency.

Note: if there are multiple recipients, an attack is possible where
one recipient modifies the content without other recipients noticing
[BON]. A sending agent who is concerned with such an attack SHOULD
use a separate AuthenticatedData for each recipient.

4.1.3 Actions of the receiving agent

The receiving agent uses the same actions as for EnvelopedData with
1-Pass ECMQV, as specified in Section 3.2.3 of this document.

Note: see Note in Section 4.1.2.

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5 Recommended Algorithms and Elliptic Curves

Implementations of this specification MUST implement either
SignedData with ECDSA or EnvelopedData with ephemeral-static ECDH.
Implementations of this specification SHOULD implement both
SignedData with ECDSA and EnvelopedData with ephemeral-static ECDH.
Implementations MAY implement the other techniques specified, such as
AuthenticatedData and 1-Pass ECMQV.

Furthermore, in order to encourage interoperability, implementations
SHOULD use the elliptic curve domain parameters specified by ANSI
[X9.62], NIST [FIPS-186-2] and SECG [SEC2].

6 Certificates using ECC

Internet X.509 certificates [PKI] can be used in conjunction with
this specification to distribute agents' public keys. The use of ECC
algorithms and keys within X.509 certificates is specified in [PKI-
ALG].

7 SMIMECapabilities Attribute and ECC

A sending agent MAY announce to receiving agents that it supports one
or more of the ECC algorithms in this document by using the
SMIMECapabilities signed attribute [MSG, Section 2.5.2].

The SMIMECapability value to indicate support for the ECDSA signature
algorithm is the SEQUENCE with the capabilityID field containing the
object identifier ecdsa-with-SHA1 with NULL parameters. The DER
encoding is:

30 0b 06 07 2a 86 48 ce 3d 04 01 05 00

The SMIMECapability capabilityID object identifiers for the supported
key agreement algorithms in this document are dhSinglePass-stdDH-
sha1kdf-scheme, dhSinglePass-cofactorDH-sha1kdf-scheme, and
mqvSinglePass-sha1kdf-scheme. For each of these SMIMECapability
SEQUENCEs, the parameters field is present and indicates the
supported key-encryption algorithm with the KeyWrapAlgorithm
algorithm identifier. The DER encodings that indicate capability of
the three key agreement algorithms with CMS Triple-DES key wrap are:

30 1c 06 09 2b 81 05 10 86 48 3f 00 02 30 0f 06
0b 2a 86 48 86 f7 0d 01 09 10 03 06 05 00

for ephemeral-static ECDH,

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30 1c 06 09 2b 81 05 10 86 48 3f 00 03 30 0f 06
0b 2a 86 48 86 f7 0d 01 09 10 03 06 05 00

for ephemeral-static ECDH with cofactor method, and

30 1c 06 09 2b 81 05 10 86 48 3f 00 10 30 0f 06
0b 2a 86 48 86 f7 0d 01 09 10 03 06 05 00

for ECMQV.

8 ASN.1 Syntax

The ASN.1 syntax used in this document is gathered in this section
for reference purposes.

8.1 Algorithm identifiers

The algorithm identifiers used in this document are taken from
[X9.62], [SEC1] and [SEC2].

The following object identifier indicates the hash algorithm used in
this document:

sha-1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
oiw(14) secsig(3) algorithm(2) 26 }

The following object identifier is used in this document to indicate
an elliptic curve public key:

id-ecPublicKey OBJECT IDENTIFIER ::= { ansi-x9-62 keyType(2) 1 }

where

ansi-x9-62 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
10045 }

When the object identifier id-ecPublicKey is used here with an
algorithm identifier, the associated parameters contain NULL.

The following object identifier indicates the digital signature
algorithm used in this document:

ecdsa-with-SHA1 OBJECT IDENTIFIER ::= { ansi-x9-62 signatures(4)
1 }

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When the object identifier ecdsa-with-SHA1 is used within an
algorithm identifier, the associated parameters field contains NULL.

The following object identifiers indicate the key agreement
algorithms used in this document:

dhSinglePass-stdDH-sha1kdf-scheme OBJECT IDENTIFIER ::= {
x9-63-scheme 2}

dhSinglePass-cofactorDH-sha1kdf-scheme OBJECT IDENTIFIER ::= {
x9-63-scheme 3}

mqvSinglePass-sha1kdf-scheme OBJECT IDENTIFIER ::= {
x9-63-scheme 16}

where

x9-63-scheme OBJECT IDENTIFIER ::= { iso(1)
identified-organization(3) tc68(133) country(16) x9(840)
x9-63(63) schemes(0) }

When the object identifiers are used here within an algorithm
identifier, the associated parameters field contains the CMS
KeyWrapAlgorithm algorithm identifier.

8.2 Other syntax

The following additional syntax is used here.

When using ECDSA with SignedData, ECDSA signatures are encoded using
the type:

ECDSA-Sig-Value ::= SEQUENCE {
r INTEGER,
s INTEGER }

ECDSA-Sig-Value is specified in [X9.62]. Within CMS, ECDSA-Sig-Value
is DER-encoded and placed within a signature field of SignedData.

When using ECDH and ECMQV with EnvelopedData and AuthenticatedData,
ephemeral and static public keys are encoded using the type ECPoint.

ECPoint ::= OCTET STRING

When using ECMQV with EnvelopedData and AuthenticatedData, the
sending agent's ephemeral public key and additional keying material
are encoded using the type:

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MQVuserKeyingMaterial ::= SEQUENCE {
ephemeralPublicKey OriginatorPublicKey,
addedukm [0] EXPLICIT UserKeyingMaterial OPTIONAL }

The ECPoint syntax in used to represent the ephemeral public key and
placed in the ephemeralPublicKey field. The additional user keying
material is placed in the addedukm field. Then the
MQVuserKeyingMaterial value is DER-encoded and placed within a ukm
field of EnvelopedData or AuthenticatedData.

When using ECDH or ECMQV with EnvelopedData or AuthenticatedData, the
key-encryption keys are derived by using the type:

ECC-CMS-SharedInfo ::= SEQUENCE {
keyInfo AlgorithmIdentifier,
entityUInfo [0] EXPLICIT OCTET STRING OPTIONAL,
suppPubInfo [2] EXPLICIT OCTET STRING }

The fields of ECC-CMS-SharedInfo are as follows:

keyInfo contains the object identifier of the key-encryption
algorithm (used to wrap the CEK) and NULL parameters.

entityUInfo optionally contains additional keying material
supplied by the sending agent. When used with ECDH and CMS, the
entityUInfo field contains the octet string ukm. When used with
ECMQV and CMS, the entityUInfo contains the octet string addedukm
(encoded in MQVuserKeyingMaterial).

suppPubInfo contains the length of the generated KEK, in bits,
represented as a 32 bit number, as in [CMS-DH]. (E.g. for 3DES it
would be 00 00 00 c0.)

Within CMS, ECC-CMS-SharedInfo is DER-encoded and used as input to
the key derivation function, as specified in [SEC1, Section 3.6.1].
Note that ECC-CMS-SharedInfo differs from the OtherInfo specified in
[CMS-DH]. Here, a counter value is not included in the keyInfo field
because the key derivation function specified in [SEC1, Section
3.6.1] ensures that sufficient keying data is provided.

9 Summary

This document specifies how to use ECC algorithms with the S/MIME
CMS. Use of ECC algorithm within CMS can result in reduced
processing requirements for S/MIME agents, and reduced bandwidth for
CMS messages.

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References

[X9.62] ANSI X9.62-1998, "Public Key Cryptography For The
Financial Services Industry: The Elliptic Curve Digital
Signature Algorithm (ECDSA)", American National
Standards Institute, 1999.

[PKI-ALG] Bassham, L., Housley R. and W. Polk, "Algorithms and
Identifiers for the Internet X.509 Public Key
Infrastructure Certificate and CRL Profile", RFC 3279,
April 2002.

[BON] D. Boneh, "The Security of Multicast MAC", Presentation
at Selected Areas of Cryptography 2000, Center for
Applied Cryptographic Research, University of Waterloo,
2000. Paper version available from
http://crypto.stanford.edu/~dabo/papers/mmac.ps

[MUST] Bradner, S., "Key Words for Use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[FIPS-180] FIPS 180-1, "Secure Hash Standard", National Institute
of Standards and Technology, April 17, 1995.

[FIPS-186-2] FIPS 186-2, "Digital Signature Standard", National
Institute of Standards and Technology, 15 February 2000.

[PKI] Housley, R., Polk, W., Ford, W. and D. Solo, "Internet
X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile", RFC 3280,
April 2002.

[CMS] Housley, R., "Cryptographic Message Syntax", RFC 2630,
June 1999.

[IEEE1363] IEEE P1363, "Standard Specifications for Public Key
Cryptography", Institute of Electrical and Electronics
Engineers, 2000.

[K] B. Kaliski, "MQV Vulnerabilty", Posting to ANSI X9F1 and
IEEE P1363 newsgroups, 1998.

[LMQSV] L. Law, A. Menezes, M. Qu, J. Solinas and S. Vanstone,
"An efficient protocol for authenticated key agreement",
Technical report CORR 98-05, University of Waterloo,
1998.

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RFC 3278 Use of ECC Algorithms in CMS April 2002

[CMS-KEA] Pawling, J., "CMS KEA and SKIPJACK Conventions", RFC
2876, July 2000.

[MSG] Ramsdell, B., "S/MIME Version 3 Message Specification",
RFC 2633, June 1999.

[CMS-DH] Rescorla, E., "Diffie-Hellman Key Agreement Method", RFC
2631, June 1999.

[SEC1] SECG, "Elliptic Curve Cryptography", Standards for
Efficient Cryptography Group, 2000. Available from
www.secg.org/collateral/sec1.pdf.

[SEC2] SECG, "Recommended Elliptic Curve Domain Parameters",
Standards for Efficient Cryptography Group, 2000.
Available from www.secg.org/collateral/sec2.pdf.

Security Considerations

This specification is based on [CMS], [X9.62] and [SEC1] and the
appropriate security considerations of those documents apply.

In addition, implementors of AuthenticatedData should be aware of the
concerns expressed in [BON] when using AuthenticatedData to send
messages to more than one recipient. Also, users of MQV should be
aware of the vulnerability in [K].

When 256, 384, and 512 bit hash functions succeed SHA-1 in future
revisions of [FIPS], [FIPS-186-2], [X9.62] and [SEC1], then they can
similarly succeed SHA-1 in a future revision of this document.

Intellectual Property Rights

The IETF has been notified of intellectual property rights claimed in
regard to the specification contained in this document. For more
information, consult the online list of claimed rights
(http://www.ietf.org/ipr.html).

The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP 11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to

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obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.

Acknowledgments

The methods described in this document are based on work done by the
ANSI X9F1 working group. The authors wish to extend their thanks to
ANSI X9F1 for their assistance. The authors also wish to thank Peter
de Rooij for his patient assistance. The technical comments of
Francois Rousseau were valuable contributions.

Authors' Addresses

Simon Blake-Wilson
Certicom Corp
5520 Explorer Drive #400
Mississauga, ON L4W 5L1

EMail: [email protected]

Daniel R. L. Brown
pCerticom Corp
5520 Explorer Drive #400
Mississauga, ON L4W 5L1

EMail: [email protected]

Paul Lambert

EMail: [email protected]

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Full Copyright Statement

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