Generic Security Service Application Program Interface (GSS-API) Key Exchange with SHA-2
RFC 8732
Document | Type |
RFC - Proposed Standard
(February 2020; No errata)
Updates RFC 4462
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|
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Authors | Simo Sorce , Hubert Kario | ||
Last updated | 2020-02-28 | ||
Replaces | draft-ssorce-gss-keyex-sha2 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html xml pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Daniel Migault | ||
Shepherd write-up | Show (last changed 2018-02-23) | ||
IESG | IESG state | RFC 8732 (Proposed Standard) | |
Action Holders |
(None)
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||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Benjamin Kaduk | ||
Send notices to | Daniel Migault <daniel.migault@ericsson.com> | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | RFC-Ed-Ack |
Internet Engineering Task Force (IETF) S. Sorce Request for Comments: 8732 H. Kario Updates: 4462 Red Hat, Inc. Category: Standards Track February 2020 ISSN: 2070-1721 Generic Security Service Application Program Interface (GSS-API) Key Exchange with SHA-2 Abstract This document specifies additions and amendments to RFC 4462. It defines a new key exchange method that uses SHA-2 for integrity and deprecates weak Diffie-Hellman (DH) groups. The purpose of this specification is to modernize the cryptographic primitives used by Generic Security Service (GSS) key exchanges. 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/rfc8732. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction 2. Rationale 3. Document Conventions 4. New Diffie-Hellman Key Exchange Methods 5. New Elliptic Curve Diffie-Hellman Key Exchange Methods 5.1. Generic GSS-API Key Exchange with ECDH 5.2. ECDH Key Exchange Methods 6. Deprecated Algorithms 7. IANA Considerations 8. Security Considerations 8.1. New Finite Field DH Mechanisms 8.2. New Elliptic Curve DH Mechanisms 8.3. GSS-API Delegation 9. References 9.1. Normative References 9.2. Informative References Authors' Addresses 1. Introduction Secure Shell (SSH) Generic Security Service Application Program Interface (GSS-API) methods [RFC4462] allow the use of GSS-API [RFC2743] for authentication and key exchange in SSH. [RFC4462] defines three exchange methods all based on DH groups and SHA-1. This document updates [RFC4462] with new methods intended to support environments that desire to use the SHA-2 cryptographic hash functions. 2. Rationale Due to security concerns with SHA-1 [RFC6194] and with modular exponentiation (MODP) groups with less than 2048 bits [NIST-SP-800-131Ar2], we propose the use of hashes based on SHA-2 [RFC6234] with DH group14, group15, group16, group17, and group18 [RFC3526]. Additionally, we add support for key exchange based on Elliptic Curve Diffie-Hellman with the NIST P-256, P-384, and P-521 [SEC2v2], as well as the X25519 and X448 [RFC7748] curves. Following the practice of [RFC8268], only SHA-256 and SHA-512 hashes are used for DH groups. For NIST curves, the same curve-to-hashing algorithm pairing used in [RFC5656] is adopted for consistency. 3. Document Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 4. New Diffie-Hellman Key Exchange Methods This document adopts the same naming convention defined in [RFC4462] to define families of methods that cover any GSS-API mechanism used with a specific Diffie-Hellman group and SHA-2 hash combination. +--------------------------+--------------------------------+ | Key Exchange Method Name | Implementation Recommendations | +==========================+================================+ | gss-group14-sha256-* | SHOULD/RECOMMENDED | +--------------------------+--------------------------------+ | gss-group15-sha512-* | MAY/OPTIONAL | +--------------------------+--------------------------------+ | gss-group16-sha512-* | SHOULD/RECOMMENDED | +--------------------------+--------------------------------+ | gss-group17-sha512-* | MAY/OPTIONAL |Show full document text