Quantum-Resistant GSS-API Key Exchange for SSH
draft-kario-gss-qr-kex-00

Document Type Active Internet-Draft (individual)
Author Hubert Kario 
Last updated 2020-10-01
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Internet Engineering Task Force                                 H. Kario
Internet-Draft                                             Red Hat, Inc.
Updates: 4462 (if approved)                                 Sep 30, 2020
Intended status: Standards Track
Expires: April 3, 2021

             Quantum-Resistant GSS-API Key Exchange for SSH
                       draft-kario-gss-qr-kex-00

Abstract

   This document specifies additions and amendments to RFC4462.  It
   defines a new key exchange method that uses GSS-API in a way to
   provide key exchange method that is resistant to attacks by quantum
   computers.  The purpose of this specification is to provide an easy-
   to-implement upgrade to environments that require resistance against
   quantum computers before widely accepted post-quantum cryptography
   algorithms are established.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 3, 2021.

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

Kario                     Expires April 3, 2021                 [Page 1]
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   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
   2.  Rationale . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Document Conventions  . . . . . . . . . . . . . . . . . . . .   3
   4.  New Quantum Resistant Key Exchange Methods  . . . . . . . . .   3
     4.1.  Generic Quantum Resistant GSS-API key Exchange  . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
     6.1.  Symmetric cipher security . . . . . . . . . . . . . . . .   7
     6.2.  User authentication . . . . . . . . . . . . . . . . . . .   8
     6.3.  Used GSSAPI Mechanisms  . . . . . . . . . . . . . . . . .   8
     6.4.  GSSAPI Delegation . . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   SSH GSS-API Methods [RFC4462] allows the use of GSSAPI for
   authentication and key exchange in SSH.  Unfortunately for resistance
   against quantum computers all of the methods in RFC 4462 as well as
   all of the new methods introduced in SSH GSS-API SHA-2 Methods
   [RFC8732] derive their security from Finite-Field Diffie-Hellman or
   Elliptic Curve Diffie-Hellman key exchanges.  Both FFDH and ECDH are
   believed to be vulnerable to Shor's algorithm running on quantum
   computers.  This document updates RFC4462 with new methods intended
   for use in environments where use of quantum resistant algorithms is
   more important that the forward secrecy provided by FFDH and ECDH.

2.  Rationale

   Due to security concerns with FFDH and ECDH against attacks using
   quantum computers, we propose a new key exchange method that does not
   use FFDH or ECDH to agree on a shared secret to derive later
   encryption keys but rather uses GSS-API as a secure communication
   channel to exchange secrets that are then used to derive encryption
   keys.

   To provide resistance against quantum computer attacks the connection
   needs to also carefully select encryption ciphers, and host
   authentication methods.

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3.  Document Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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