Public Key Cryptography for Initial Authentication in Kerberos (PKINIT) Freshness Extension
RFC 8070
Document | Type | RFC - Proposed Standard (February 2017; No errata) | |
---|---|---|---|
Authors | Michiko Short , Seth Moore , Paul Miller | ||
Last updated | 2017-02-16 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Matt Rogers | ||
Shepherd write-up | Show (last changed 2016-10-18) | ||
IESG | IESG state | RFC 8070 (Proposed Standard) | |
Action Holders |
(None)
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Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Stephen Farrell | ||
Send notices to | mrogers@redhat.com | ||
IANA | IANA review state | IANA OK - Actions Needed | |
IANA action state | RFC-Ed-Ack |
Internet Engineering Task Force (IETF) M. Short, Ed. Request for Comments: 8070 S. Moore Category: Standards Track P. Miller ISSN: 2070-1721 Microsoft Corporation February 2017 Public Key Cryptography for Initial Authentication in Kerberos (PKINIT) Freshness Extension Abstract This document describes how to further extend the Public Key Cryptography for Initial Authentication in Kerberos (PKINIT) extension (defined in RFC 4556) to exchange an opaque data blob that a Key Distribution Center (KDC) can validate to ensure that the client is currently in possession of the private key during a PKINIT Authentication Service (AS) exchange. 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 http://www.rfc-editor.org/info/rfc8070. Copyright Notice Copyright (c) 2017 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. Short, et al. Standards Track [Page 1] RFC 8070 PKINIT Freshness February 2017 Table of Contents 1. Introduction ....................................................2 1.1. Kerberos Message Flow Using KRB_AS_REQ without Pre-authentication .........................................3 1.2. Requirements Language ......................................3 2. Message Exchanges ...............................................4 2.1. Generation of KRB_AS_REQ Message ...........................4 2.2. Generation of KRB_ERROR Message ............................4 2.3. Generation of KRB_AS_REQ Message ...........................4 2.4. Receipt of KRB_AS_REQ Message ..............................5 2.5. Receipt of Second KRB_ERROR Message ........................5 3. PreAuthentication Data Types ....................................5 4. Extended PKAuthenticator ........................................6 5. IANA Considerations .............................................6 6. Security Considerations .........................................7 7. Interoperability Considerations .................................7 8. Normative References ............................................8 Acknowledgements ...................................................8 Authors' Addresses .................................................9 1. Introduction The Kerberos PKINIT extension [RFC4556] defines two schemes for using asymmetric cryptography in a Kerberos pre-authenticator. One uses Diffie-Hellman key exchange and the other depends on public key encryption. The public key encryption scheme is less commonly used for two reasons: o Elliptic Curve Cryptography (ECC) Support for PKINIT [RFC5349] only specified Elliptic Curve Diffie-Hellman (ECDH) key agreement, so it cannot be used for public key encryption. o Public key encryption requires certificates with an encryption key, which is not deployed on many existing smart cards. In the Diffie-Hellman exchange, the client uses its private key only to sign the AuthPack structure (specified in Section 3.2.1 of [RFC4556]), which is performed before any traffic is sent to the KDC. Thus, a client can generate requests with future times in the PKAuthenticator, and then send those requests at those future times. Unless the time is outside the validity period of the client's certificate, the KDC will validate the PKAuthenticator and return a Ticket-Granting Ticket (TGT) the client can use without possessing the private key. Short, et al. Standards Track [Page 2] RFC 8070 PKINIT Freshness February 2017Show full document text