Internet DRAFT - draft-kuehlewind-crypto-sep
draft-kuehlewind-crypto-sep
Network Working Group M. Kuehlewind
Internet-Draft ETH Zurich
Intended status: Informational March 13, 2017
Expires: September 14, 2017
Separating Crypto Negotiation and Communication
draft-kuehlewind-crypto-sep-00
Abstract
Based on the increasing deployment of session resumption mechanisms
where cryptographic context can be resumed to transmit application
data with the first packet without delay for connection setup and
negotiation, this draft proposes a split to separate connections used
to set up encryption context and negotiate capabilities from
connections used to transmit application data. While cryptographic
context and endpoint capabilities need to be be known before
encrypted application data can be sent, there is otherwise no
technical constraint that the crypto handshake has to be performed on
the same transport connection. This document discusses requirements
on the cryptographic protocol to establish medium- to long-lived
association that can be used by different transport protocols that
implement different transport services.
Status of This Memo
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This Internet-Draft will expire on September 14, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Support for different transport services . . . . . . . . 3
2.2. Cryptographic context lifetime management . . . . . . . . 3
3. Crypto-Transport Interface . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4
7. Informative References . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
New cryptographic and transport protocols increasingly rely on
session resumption mechanisms where cryptographic context can be
resumed to transmit application data with the first packet without
delay for connection setup and negotiation. This draft proposed a
split to separate connections that are used to set up encryption
context and negotiate capabilities from the connection that is used
to transmit application data. In this draft we assume the use of TCP
with a TLS-like protocol for cryptographic handshake and negotiation
of endpoint capabilities, where TCP provides a fully reliable stream-
based transport and the message framing is realized by TLS. However,
instead of using the same transport TCP connection for TLS or any new
TLS-like protocol, the connection will be closed after the
cryptographic handshake and a new transport connection that might not
use TCP is open at anytime to transmit the actual application data.
In the case where there is no cryptographic context available when an
application expressed the wish to transmit data to a certain
endpoint, the connection for crypto negotiation must be established
first, immediately before the actual payload connection will be used.
In this case, as today for approaches that integrate both the
cryptographic handshake and the payload transmission, the application
data transmission is delayed until the needed cryptographic context
is available. Just using a separate transport connection for these
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two actions does not generally introduce any extra delay. However,
given that these steps don't have to be performed at the same time,
crypto negotiation could even be performed (long) before the
application expresses a desire to send data. E.g. an integrated or
independent software system could maintain knowledge about endpoints
that are likely to be communication points and set up or refresh
state any time triggered by external events such as the start up of
this system or periodically.
This document discusses high-level requirements for a future TLS-like
crypto protocol that provides support for this connection separation
as well as possible interfaces between the cryptographic protocol and
the transport protocol that is used for the transmission of the
application data.
[I-D.moskowitz-sse] proposes a similar approach. However while
[I-D.moskowitz-sse] proposes a new protocol to negotiate and maintain
long-term cryptographic sessions, this document relies on the use of
existing protocols and only discusses requirements for the evolution
of these protocols and exchange of information within one endpoint
locally.
2. Requirements
2.1. Support for different transport services
[editor's note: this section will discuss requirement for crypto
protocols to provide cryptographic context that can support different
transport feature e.g. partial or non-reliable transports]
2.2. Cryptographic context lifetime management
[editor's note: this section will discuss lifetime management of
long-lived cryptographic associations, e.g. when to set up or
refresh state for which endpoint and which transport protocols]
3. Crypto-Transport Interface
There are two basic approaches: either the transport protocol can
provide data to the crypto engine and get back an encrypted version
of the data to be sent, or the crypto protocol can provide keying
material and inform the transport about the negotiated capabilities
of the far end and the transport is responsible to perform the
encryption set.
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4. IANA Considerations
This docuement has on request to IANA.
5. Security Considerations
[editor's note: this section will be added later. However, this
document discusses the use of cryptograohic context for transport
connections and as such it has security relevant consideration within
the whole document.]
6. Acknowledgments
This work is partially supported by the European Commission under
Horizon 2020 grant agreement no. 688421 Measurement and Architecture
for a Middleboxed Internet (MAMI), and by the Swiss State Secretariat
for Education, Research, and Innovation under contract no. 15.0268.
This support does not imply endorsement.
7. Informative References
[I-D.moskowitz-sse]
Moskowitz, R., Faynberg, I., Lu, H., Hares, S., and P.
Giacomin, "Session Security Envelope", draft-moskowitz-
sse-04 (work in progress), October 2016.
Author's Address
Mirja Kuehlewind
ETH Zurich
Gloriastrasse 35
8092 Zurich
Switzerland
Email: mirja.kuehlewind@tik.ee.ethz.ch
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