draft-ietf-curdle-ssh-modp-dh-sha2-02.txt   draft-ietf-curdle-ssh-modp-dh-sha2-03.txt 
Internet Engineering Task Force M. Baushke Internet Engineering Task Force M. Baushke
Internet-Draft Juniper Networks, Inc. Internet-Draft Juniper Networks, Inc.
Updates: 4253, 4432 (if approved) March 6, 2017 Updates: 4253, 4432 (if approved) March 27, 2017
Intended status: Standards Track Intended status: Standards Track
Expires: September 7, 2017 Expires: September 28, 2017
More Modular Exponential (MODP) Diffie-Hellman (DH) Key Exchange (KEX) More Modular Exponential (MODP) Diffie-Hellman (DH) Key Exchange (KEX)
Groups for Secure Shell (SSH) Groups for Secure Shell (SSH)
draft-ietf-curdle-ssh-modp-dh-sha2-02 draft-ietf-curdle-ssh-modp-dh-sha2-03
Abstract Abstract
This document defines added Modular Exponential (MODP) Groups for the This document defines added Modular Exponential (MODP) Groups for the
Secure Shell (SSH) protocol using SHA-2 hashes. Secure Shell (SSH) protocol using SHA-2 hashes.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 7, 2017. This Internet-Draft will expire on September 28, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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transport of Top Secret information. For this reason, the new MODP transport of Top Secret information. For this reason, the new MODP
groups are being introduced starting with the MODP 3072-bit group 15 groups are being introduced starting with the MODP 3072-bit group 15
are all using SHA2-512 as the hash algorithm. are all using SHA2-512 as the hash algorithm.
The DH 2048-bit MODP group 14 is already present in most SSH The DH 2048-bit MODP group 14 is already present in most SSH
implementations and most implementations already have a SHA2-256 implementations and most implementations already have a SHA2-256
implementation, so diffie-hellman-group14-sha256 is provided as an implementation, so diffie-hellman-group14-sha256 is provided as an
easy to implement and faster to use key exchange for small embedded easy to implement and faster to use key exchange for small embedded
applications. applications.
Please send comments on this draft to ietf-ssh@NetBSD.org and ietf- [TO BE REMOVED: Please send comments on this draft to
curdle@ietf.org. curdle@ietf.org.]
2. Requirements Language 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Key Exchange Algorithms 3. Key Exchange Algorithms
This memo adopts the style and conventions of [RFC4253] in specifying This memo adopts the style and conventions of [RFC4253] in specifying
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Figure 1 Figure 1
The SHA-2 family of secure hash algorithms are defined in The SHA-2 family of secure hash algorithms are defined in
[FIPS-180-4]. [FIPS-180-4].
The method of key exchange used for the name "diffie-hellman- The method of key exchange used for the name "diffie-hellman-
group14-sha256" is the same as that for "diffie-hellman-group14-sha1" group14-sha256" is the same as that for "diffie-hellman-group14-sha1"
except that the SHA2-256 hash algorithm is used. except that the SHA2-256 hash algorithm is used.
The method of key exchange used for the name "gss-group14-sha256-*"
is the same as that for "gss-group14-sha1-*" except that the SHA2-256
hash algorithm is used.
The group15 through group18 names are the same as those specified in The group15 through group18 names are the same as those specified in
[RFC3526] 3071-bit MODP Group 15, 4096-bit MODP Group 16, 6144-bit [RFC3526] 3071-bit MODP Group 15, 4096-bit MODP Group 16, 6144-bit
MODP Group 17, and 8192-bit MODP Group 18. MODP Group 17, and 8192-bit MODP Group 18.
The SHA2-512 algorithm is to be used when "sha512" is specified as a The SHA2-512 algorithm is to be used when "sha512" is specified as a
part of the key exchange method name. part of the key exchange method name.
4. IANA Considerations 4. IANA Considerations
This document augments the Key Exchange Method Names in [RFC4253]. This document augments the Key Exchange Method Names in [RFC4253].
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+--------+----------+----------+----------+----------+----------+ +--------+----------+----------+----------+----------+----------+
| 14 | 2048-bit | 110 | 220- | 160 | 320- | | 14 | 2048-bit | 110 | 220- | 160 | 320- |
| 15 | 3072-bit | 130 | 260- | 210 | 420- | | 15 | 3072-bit | 130 | 260- | 210 | 420- |
| 16 | 4096-bit | 150 | 300- | 240 | 480- | | 16 | 4096-bit | 150 | 300- | 240 | 480- |
| 17 | 6144-bit | 170 | 340- | 270 | 540- | | 17 | 6144-bit | 170 | 340- | 270 | 540- |
| 18 | 8192-bit | 190 | 380- | 310 | 620- | | 18 | 8192-bit | 190 | 380- | 310 | 620- |
+--------+----------+---------------------+---------------------+ +--------+----------+---------------------+---------------------+
Figure 2 Figure 2
Many users seem to be interested in the perceived safety of using
larger MODP groups and hashing with SHA2-based algorithms.
6. References 6. References
6.1. Normative References 6.1. Normative References
[FIPS-180-4] [FIPS-180-4]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard (SHS)", FIPS PUB 180-4, August 2015, Hash Standard (SHS)", FIPS PUB 180-4, August 2015,
<http://nvlpubs.nist.gov/nistpubs/FIPS/ <http://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.180-4.pdf>. NIST.FIPS.180-4.pdf>.
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