draft-ietf-kitten-pkinit-freshness-03.txt   draft-ietf-kitten-pkinit-freshness-04.txt 
Kitten Working Group M. Short, Ed. Kitten Working Group M. Short, Ed.
Internet-Draft S. Moore Internet-Draft S. Moore
Intended status: Standards Track P. Miller Intended status: Standards Track P. Miller
Expires: August 27, 2016 Microsoft Corporation Expires: September 22, 2016 Microsoft Corporation
February 24, 2016 March 21, 2016
Public Key Cryptography for Initial Authentication in Kerberos (PKINIT) Public Key Cryptography for Initial Authentication in Kerberos (PKINIT)
Freshness Extension Freshness Extension
draft-ietf-kitten-pkinit-freshness-03 draft-ietf-kitten-pkinit-freshness-04
Abstract Abstract
This document describes how to further extend the Public Key This document describes how to further extend the Public Key
Cryptography for Initial Authentication in Kerberos (PKINIT) Cryptography for Initial Authentication in Kerberos (PKINIT)
extension [RFC4556] to exchange an opaque data blob that a KDC can extension [RFC4556] to exchange an opaque data blob that a KDC can
validate to ensure that the client is currently in possession of the validate to ensure that the client is currently in possession of the
private key during a PKINIT AS exchange. private key during a PKINIT AS exchange.
Status of This Memo Status of This Memo
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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 August 27, 2016. This Internet-Draft will expire on September 22, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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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2.1. Generation of KRB_AS_REQ Message 2.1. Generation of KRB_AS_REQ Message
The client indicates support of freshness tokens by adding a padata The client indicates support of freshness tokens by adding a padata
element with padata-type PA_AS_FRESHNESS and padata-value of an empty element with padata-type PA_AS_FRESHNESS and padata-value of an empty
octet string. octet string.
2.2. Generation of KRB_ERROR Message 2.2. Generation of KRB_ERROR Message
The KDC will respond with a KRB_ERROR [RFC4120] message with the The KDC will respond with a KRB_ERROR [RFC4120] message with the
error-code KDC_ERR_PREAUTH_REQUIRED [RFC4120] and adding a padata error-code KDC_ERR_PREAUTH_REQUIRED [RFC4120] adding a padata element
element with padata-type PA_AS_FRESHNESS and padata-value of the with padata-type PA_AS_FRESHNESS and padata-value of the freshness
freshness token to the METHOD-DATA object. token to the METHOD-DATA object.
2.3. Generation of KRB_AS_REQ Message 2.3. Generation of KRB_AS_REQ Message
After the client receives the KRB-ERROR message containing a After the client receives the KRB-ERROR message containing a
freshness token, it extracts the PA_AS_FRESHNESS padata-value field freshness token, it extracts the PA_AS_FRESHNESS padata-value field
of the PA-DATA structure as an opaque data blob. The PA_AS_FRESHNESS of the PA-DATA structure as an opaque data blob. The PA_AS_FRESHNESS
padata-value field of the PA-DATA structure SHALL then be added as an padata-value field of the PA-DATA structure SHALL then be added as an
opaque blob in the freshnessToken field when the client generates the opaque blob in the freshnessToken field when the client generates the
PKAuthenticator for the PA_PK_AS_REQ message. This ensures that the PKAuthenticator for the PA_PK_AS_REQ message. This ensures that the
freshness token value will be included in the signed data portion of freshness token value will be included in the signed data portion of
the KRB_AS_REQ value. the KRB_AS_REQ value.
2.4. Receipt of KRB_AS_REQ Message 2.4. Receipt of KRB_AS_REQ Message
If the realm requires freshness and the PA_PK_AS_REQ message does not If the realm requires freshness and the PA_PK_AS_REQ message does not
contain the freshness token, the KDC MUST return a KRB_ERROR contain the freshness token, the KDC MUST return a KRB_ERROR
[RFC4120] message with the error-code KDC_ERR_PREAUTH_REQUIRED [RFC4120] message with the error-code KDC_ERR_PREAUTH_FAILED
[RFC4120] with a padata element with padata-type PA_AS_FRESHNESS and [RFC6113] with a padata element with padata-type PA_AS_FRESHNESS and
padata-value of the freshness token to the METHOD-DATA object. padata-value of the freshness token to the METHOD-DATA object.
When the PA_PK_AS_REQ message contains a freshness token, after When the PA_PK_AS_REQ message contains a freshness token, after
validating the PA_PK_AS_REQ message normally, the KDC will validate validating the PA_PK_AS_REQ message normally, the KDC will validate
the freshnessToken value in the PKAuthenticator in an implementation- the freshnessToken value in the PKAuthenticator in an implementation-
specific way. If the freshness token is not valid, the KDC MUST specific way. If the freshness token is not valid, the KDC MUST
return a KRB_ERROR [RFC4120] message with the error-code return a KRB_ERROR [RFC4120] message with the error-code
KDC_ERR_PREAUTH_EXPIRED [RFC6113]. The e-data field of the error KDC_ERR_PREAUTH_EXPIRED [RFC6113]. The e-data field of the error
contains a METHOD-DATA object [RFC4120] which specifies a valid contains a METHOD-DATA object [RFC4120] which specifies a valid
PA_AS_FRESHNESS padata-value. Since the freshness tokens are PA_AS_FRESHNESS padata-value. Since the freshness tokens are
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