Use of the Elliptic Curve Diffie-Hellman Key Agreement Algorithm with X25519 and X448 in the Cryptographic Message Syntax (CMS)
RFC 8418
Internet Engineering Task Force (IETF) R. Housley
Request for Comments: 8418 Vigil Security
Category: Standards Track August 2018
ISSN: 2070-1721
Use of the Elliptic Curve Diffie-Hellman Key Agreement Algorithm
with X25519 and X448 in the Cryptographic Message Syntax (CMS)
Abstract
This document describes the conventions for using the Elliptic Curve
Diffie-Hellman (ECDH) key agreement algorithm with curve25519 and
curve448 in the Cryptographic Message Syntax (CMS).
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by
the Internet Engineering Steering Group (IESG). Further
information on Internet Standards is available in Section 2 of
RFC 7841.
Information about the current status of this document, any
errata, and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8418.
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Housley Standards Track [Page 1]
RFC 8418 Using X25519 and X448 with CMS August 2018
Table of Contents
1. Introduction ....................................................2
1.1. Terminology ................................................3
1.2. ASN.1 ......................................................3
2. Key Agreement ...................................................3
2.1. ANSI-X9.63-KDF .............................................4
2.2. HKDF .......................................................5
3. Enveloped-data Conventions ......................................5
3.1. EnvelopedData Fields .......................................6
3.2. KeyAgreeRecipientInfo Fields ...............................6
4. Authenticated-data Conventions ..................................7
4.1. AuthenticatedData Fields ...................................8
4.2. KeyAgreeRecipientInfo Fields ...............................8
5. Authenticated-enveloped-data Conventions ........................8
5.1. AuthEnvelopedData Fields ...................................8
5.2. KeyAgreeRecipientInfo Fields ...............................8
6. Certificate Conventions .........................................9
7. Key Agreement Algorithm Identifiers .............................9
8. SMIMECapabilities Attribute Conventions ........................10
9. Security Considerations ........................................11
10. IANA Considerations ...........................................12
11. References ....................................................13
11.1. Normative References .....................................13
11.2. Informative References ...................................14
Appendix A. ASN.1 Module ..........................................16
Acknowledgements ..................................................18
Author's Address ..................................................18
1. Introduction
This document describes the conventions for using Elliptic Curve
Diffie-Hellman (ECDH) key agreement using curve25519 and curve448
[CURVES] in the Cryptographic Message Syntax (CMS) [CMS]. Key
agreement is supported in three CMS content types: the enveloped-data
content type [CMS], authenticated-data content type [CMS], and the
authenticated-enveloped-data content type [AUTHENV].
The conventions for using some Elliptic Curve Cryptography (ECC)
algorithms in CMS are described in [CMSECC]. These conventions cover
the use of ECDH with some curves other than curve25519 and curve448
[CURVES]. Those other curves are not deprecated.
Using curve25519 with Diffie-Hellman key agreement is referred to as
"X25519". Using curve448 with Diffie-Hellman key agreement is
referred to as "X448".
Housley Standards Track [Page 2]
RFC 8418 Using X25519 and X448 with CMS August 2018
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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