SPAKE Pre-Authentication
draft-ietf-kitten-krb-spake-preauth-01
Internet Engineering Task Force N. McCallum
Internet-Draft S. Sorce
Intended status: Standards Track R. Harwood
Expires: March 19, 2018 Red Hat, Inc.
G. Hudson
MIT
September 15, 2017
SPAKE Pre-Authentication
draft-ietf-kitten-krb-spake-preauth-01
Abstract
This document defines a new pre-authentication mechanism for the
Kerberos protocol that uses a password authenticated key exchange.
This document has three goals. First, increase the security of
Kerberos pre-authentication exchanges by making offline brute-force
attacks infeasible. Second, enable the use of second factor
authentication without relying on FAST. This is achieved using the
existing trust relationship established by the shared first factor.
Third, make Kerberos pre-authentication more resilient against time
synchronization errors by removing the need to transfer an encrypted
timestamp from the client.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 19, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
McCallum, et al. Expires March 19, 2018 [Page 1]
Internet-Draft SPAKE Pre-Authentication September 2017
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Properties of PAKE . . . . . . . . . . . . . . . . . . . 3
1.2. PAKE Algorithm Selection . . . . . . . . . . . . . . . . 3
1.3. PAKE and Two-Factor Authentication . . . . . . . . . . . 4
1.4. SPAKE Overview . . . . . . . . . . . . . . . . . . . . . 5
2. Document Conventions . . . . . . . . . . . . . . . . . . . . 5
3. Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. PA-ETYPE-INFO2 . . . . . . . . . . . . . . . . . . . . . 6
3.2. Cookie Support . . . . . . . . . . . . . . . . . . . . . 6
3.3. More Pre-Authentication Data Required . . . . . . . . . . 6
4. SPAKE Pre-Authentication Message Protocol . . . . . . . . . . 6
4.1. First Pass . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Second Pass . . . . . . . . . . . . . . . . . . . . . . . 7
4.3. Third Pass . . . . . . . . . . . . . . . . . . . . . . . 8
4.4. Subsequent Passes . . . . . . . . . . . . . . . . . . . . 10
4.5. Reply Key Strengthening . . . . . . . . . . . . . . . . . 10
4.6. Optimizations . . . . . . . . . . . . . . . . . . . . . . 10
5. SPAKE Parameters and Conversions . . . . . . . . . . . . . . 11
6. Transcript Checksum . . . . . . . . . . . . . . . . . . . . . 11
7. Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 12
8. Second Factor Types . . . . . . . . . . . . . . . . . . . . . 13
9. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9.1. Unauthenticated Plaintext . . . . . . . . . . . . . . . . 13
9.2. Side Channels . . . . . . . . . . . . . . . . . . . . . . 14
9.3. KDC State . . . . . . . . . . . . . . . . . . . . . . . . 14
9.4. Dictionary Attacks . . . . . . . . . . . . . . . . . . . 15
9.5. Brute Force Attacks . . . . . . . . . . . . . . . . . . . 15
9.6. Denial of Service Attacks . . . . . . . . . . . . . . . . 16
9.7. Reply-Key Encryption Type . . . . . . . . . . . . . . . . 16
9.8. KDC Authentication . . . . . . . . . . . . . . . . . . . 16
Show full document text