SHA-2 Data Integrity Verification for the Secure Shell (SSH) Transport Layer Protocol
RFC 6668
Document | Type |
RFC - Proposed Standard
(July 2012; No errata)
Updates RFC 4253
Was draft-dbider-sha2-mac-for-ssh (individual in sec area)
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Authors | Mark Baushke , denis bider | ||
Last updated | 2015-10-14 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6668 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Sean Turner | ||
IESG note | Jeffrey Hutzelman (jhutz@cmu.edu) is the document shepherd. | ||
Send notices to | jhutz@cmu.edu |
Internet Engineering Task Force (IETF) D. Bider Request for Comments: 6668 Bitvise Limited Updates: 4253 M. Baushke Category: Standards Track Juniper Networks, Inc. ISSN: 2070-1721 July 2012 SHA-2 Data Integrity Verification for the Secure Shell (SSH) Transport Layer Protocol Abstract This memo defines algorithm names and parameters for use in some of the SHA-2 family of secure hash algorithms for data integrity verification in the Secure Shell (SSH) protocol. It also updates RFC 4253 by specifying a new RECOMMENDED data integrity algorithm. 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 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6668. Copyright Notice Copyright (c) 2012 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 (http://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. Bider & Baushke Standards Track [Page 1] RFC 6668 Sha2-Transport Layer Protocol July 2012 1. Overview and Rationale The Secure Shell (SSH) [RFC4251] is a very common protocol for secure remote login on the Internet. Currently, SSH defines data integrity verification using SHA-1 and MD5 algorithms [RFC4253]. Due to recent security concerns with these two algorithms ([RFC6194] and [RFC6151], respectively), implementors and users request support for data integrity verification using some of the SHA-2 family of secure hash algorithms. 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 [RFC2119]. 2. Data Integrity Algorithms This memo adopts the style and conventions of [RFC4253] in specifying how the use of new data integrity algorithms are indicated in SSH. The following new data integrity algorithms are defined: hmac-sha2-256 RECOMMENDED HMAC-SHA2-256 (digest length = 32 bytes, key length = 32 bytes) hmac-sha2-512 OPTIONAL HMAC-SHA2-512 (digest length = 64 bytes, key length = 64 bytes) Figure 1 The Hashed Message Authentication Code (HMAC) mechanism was originally defined in [RFC2104] and has been updated in [RFC6151]. The SHA-2 family of secure hash algorithms is defined in [FIPS-180-3]. Sample code for the SHA-based HMAC algorithms are available in [RFC6234]. The variants, HMAC-SHA2-224 and HMAC-SHA2-384 algorithms, were considered but not added to this list as they have the same computational requirements of HMAC-SHA2-256 and HMAC-SHA2-512, respectively, and do not seem to be much used in practice. Bider & Baushke Standards Track [Page 2] RFC 6668 Sha2-Transport Layer Protocol July 2012 Test vectors for use of HMAC with SHA-2 are provided in [RFC4231]. Users, implementors, and administrators may choose to put these new MACs into the proposal ahead of the REQUIRED hmac-sha1 algorithm defined in [RFC4253] so that they are negotiated first. 3. IANA Considerations This document augments the MAC Algorithm Names in [RFC4253] and [RFC4250]. IANA has updated the "Secure Shell (SSH) Protocol Parameters" registry with the following entries: MAC Algorithm Name Reference Note hmac-sha2-256 RFC 6668 Section 2 hmac-sha2-512 RFC 6668 Section 2 Figure 2 4. Security Considerations The security considerations of RFC 4253 [RFC4253] apply to thisShow full document text