A PFS-preserving protocol for LURK
draft-erb-lurk-rsalg-00

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Network Working Group                                             S. Erb
Internet-Draft                                                   R. Salz
Intended status: Standards Track                     Akamai Technologies
Expires: September 19, 2016                               March 18, 2016

                   A PFS-preserving protocol for LURK
                        draft-erb-lurk-rsalg-00

Abstract

   This document defines a protocol between a content provider and an
   external key owner that enables the provider to act as a TLS
   termination end-point for the key owner, without having the key
   actually being provisioned at the provider.

   The protocol between the two preserves forward secrecy, and is also
   designed to prevent the use of the key owner as a general-purpose
   signing oracle which would make it complicit in attacks against uses
   of the very keys it is trying to protect.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on September 19, 2016.

Copyright Notice

   Copyright (c) 2016 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

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   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Goals and Non-Goals . . . . . . . . . . . . . . . . . . . . .   3
   3.  Protocol Overview . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Server Key Exchange . . . . . . . . . . . . . . . . . . .   3
     3.2.  RSALG . . . . . . . . . . . . . . . . . . . . . . . . . .   3
       3.2.1.  Implementation Note - Modified Bleichenbacher Attack    4
       3.2.2.  Implementation Note - Hash Calculation  . . . . . . .   4
   4.  LURK Message Formats  . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Request Message . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Response Message  . . . . . . . . . . . . . . . . . . . .   6
   5.  Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   Three entities are involved in this protocol, although only two
   actually

   participate in the protocol exchanges:

         Client    <----->    Server    <---->    KeyOwner

   The "KeyOwner" is an entity holding a Certificate and associated
   private Key, typically bound to an identity such as a DNS name.

   The "server" acts on behalf of the KeyOwner, such as terminating TLS
   connections.  From external appearances, such as TLS peer name
   verification, the server is indistinguishable from the KeyOwner.

   The "client" is the end-entity that initiates a connection to the
   server.

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2.  Goals and Non-Goals

   It is not a goal to protect against an active attacker who can
   decrypt or actively MiTM any of the traffic.

   It is not a goal to protect Client-Server traffic in the event of a
   full compromise of a KeyOwner private key.

   This protocol can support Client-Server communications from SSLv3 up
   through TLS 1.2.  (TLS 1.3 will have to be evaluated at a later
   date.)

   Past Client-Server communications must remain private in the event
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