< draft-ietf-httpbis-http2-encryption-09.txt   draft-ietf-httpbis-http2-encryption-10.txt >
HTTP Working Group M. Nottingham HTTP Working Group M. Nottingham
Internet-Draft Internet-Draft
Intended status: Experimental M. Thomson Intended status: Experimental M. Thomson
Expires: June 24, 2017 Mozilla Expires: August 4, 2017 Mozilla
December 21, 2016 January 31, 2017
Opportunistic Security for HTTP Opportunistic Security for HTTP
draft-ietf-httpbis-http2-encryption-09 draft-ietf-httpbis-http2-encryption-10
Abstract Abstract
This document describes how "http" URIs can be accessed using This document describes how "http" URIs can be accessed using
Transport Layer Security (TLS) to mitigate pervasive monitoring Transport Layer Security (TLS) to mitigate pervasive monitoring
attacks. attacks.
Note to Readers Note to Readers
Discussion of this draft takes place on the HTTP working group Discussion of this draft takes place on the HTTP working group
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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 June 24, 2017. This Internet-Draft will expire on August 4, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2017 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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Goals and Non-Goals . . . . . . . . . . . . . . . . . . . 3 1.1. Goals and Non-Goals . . . . . . . . . . . . . . . . . . . 3
1.2. Notational Conventions . . . . . . . . . . . . . . . . . 3 1.2. Notational Conventions . . . . . . . . . . . . . . . . . 3
2. Using HTTP URIs over TLS . . . . . . . . . . . . . . . . . . 3 2. Using HTTP URIs over TLS . . . . . . . . . . . . . . . . . . 3
2.1. Alternative Server Opt-In . . . . . . . . . . . . . . . . 4 2.1. Alternative Server Opt-In . . . . . . . . . . . . . . . . 4
2.2. Interaction with "https" URIs . . . . . . . . . . . . . . 5 2.2. Interaction with "https" URIs . . . . . . . . . . . . . . 5
2.3. The "http-opportunistic" well-known URI . . . . . . . . . 5 2.3. The "http-opportunistic" well-known URI . . . . . . . . . 5
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4.1. Security Indicators . . . . . . . . . . . . . . . . . . . 6 4.1. Security Indicators . . . . . . . . . . . . . . . . . . . 6
4.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 6 4.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 7
4.3. Privacy Considerations . . . . . . . . . . . . . . . . . 6 4.3. Privacy Considerations . . . . . . . . . . . . . . . . . 7
4.4. Confusion Regarding Request Scheme . . . . . . . . . . . 6 4.4. Confusion Regarding Request Scheme . . . . . . . . . . . 7
4.5. Server Controls . . . . . . . . . . . . . . . . . . . . . 7 4.5. Server Controls . . . . . . . . . . . . . . . . . . . . . 7
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Normative References . . . . . . . . . . . . . . . . . . 7 5.1. Normative References . . . . . . . . . . . . . . . . . . 8
5.2. Informative References . . . . . . . . . . . . . . . . . 8 5.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
This document describes a use of HTTP Alternative Services [RFC7838] This document describes a use of HTTP Alternative Services [RFC7838]
to decouple the URI scheme from the use and configuration of to decouple the URI scheme from the use and configuration of
underlying encryption, allowing a "http" URI [RFC7230] to be accessed underlying encryption, allowing a "http" URI [RFC7230] to be accessed
using Transport Layer Security (TLS) [RFC5246] opportunistically. using Transport Layer Security (TLS) [RFC5246] opportunistically.
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A client can also explicitly probe for an alternative service A client can also explicitly probe for an alternative service
advertisement by sending a request that bears little or no sensitive advertisement by sending a request that bears little or no sensitive
information, such as one with the OPTIONS method. Likewise, clients information, such as one with the OPTIONS method. Likewise, clients
with existing alternative services information could make such a with existing alternative services information could make such a
request before they expire, in order minimize the delays that might request before they expire, in order minimize the delays that might
be incurred. be incurred.
Client certificates are not meaningful for URLs with the "http" Client certificates are not meaningful for URLs with the "http"
scheme, and therefore clients creating new TLS connections to scheme, and therefore clients creating new TLS connections to
alternative services for the purposes of this specification MUST NOT alternative services for the purposes of this specification MUST NOT
present them. Connections that use client certificates for other present them. A server that also provides "https" resources on the
reasons MAY be reused, though client certificates MUST NOT affect the same port can request a certificate during the TLS handshake, but it
responses to requests for "http" resources. MUST NOT abort the handshake if the client does not provide one.
2.1. Alternative Server Opt-In 2.1. Alternative Server Opt-In
It is possible that the server might become confused about whether It is possible that the server might become confused about whether
requests' URLs have a "http" or "https" scheme, for various reasons; requests' URLs have a "http" or "https" scheme, for various reasons;
see Section 4.4. To ensure that the alternative service has opted see Section 4.4. To ensure that the alternative service has opted
into serving "http" URLs over TLS, clients are required to perform into serving "http" URLs over TLS, clients are required to perform
additional checks before directing "http" requests to it. additional checks before directing "http" requests to it.
Clients MUST NOT send "http" requests over a secured connection, Clients MUST NOT send "http" requests over a secured connection,
unless the chosen alternative service presents a certificate that is unless the chosen alternative service presents a certificate that is
valid for the origin - as per [RFC2818] (this also establishes valid for the origin as defined in [RFC2818]. Using an authenticated
"reasonable assurances" for the purposes of {RFC7838}}) - and they alternative service establishes "reasonable assurances" for the
have obtained a valid http-opportunistic response for an origin (as purposes of {RFC7838}}. In addition to authenticating the server,
per Section 2.3). the client MUST have obtained a valid http-opportunistic response for
an origin (as per Section 2.3) using the authenticated connection.
An exception to the latter restriction is made for requests for the
"http-opportunistic" well-known URI.
For example, assuming the following request is made over a TLS For example, assuming the following request is made over a TLS
connection that is successfully authenticated for those origins, the connection that is successfully authenticated for those origins, the
following request/response pair would allow requests for the origins following request/response pair would allow requests for the origins
"http://www.example.com" or "http://example.com" to be sent using a "http://www.example.com" or "http://example.com" to be sent using a
secured connection: secured connection:
HEADERS HEADERS
+ END_STREAM + END_STREAM
+ END_HEADERS + END_HEADERS
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:path = /.well-known/http-opportunistic :path = /.well-known/http-opportunistic
host: example.com host: example.com
HEADERS HEADERS
:status = 200 :status = 200
content-type = application/json content-type = application/json
DATA DATA
+ END_STREAM + END_STREAM
[ "http://www.example.com", "http://example.com" ] [ "http://www.example.com", "http://example.com" ]
Though this document describes multiple origins, this is only for
operational convenience. Only a request made to an origin (over an
authenticated connection) can be used to acquire this resource for
that origin. Thus in the example, the request to
"http://example.com" cannot be assumed to also provide an http-
opportunistic response for "http://www.example.com".
2.2. Interaction with "https" URIs 2.2. Interaction with "https" URIs
Clients MUST NOT send "http" requests and "https" requests on the Clients MUST NOT send "http" requests and "https" requests on the
same connection. Similarly, clients MUST NOT send "http" requests same connection. Similarly, clients MUST NOT send "http" requests
for multiple origins on the same connection. for multiple origins on the same connection.
2.3. The "http-opportunistic" well-known URI 2.3. The "http-opportunistic" well-known URI
This specification defines the "http-opportunistic" well-known URI This specification defines the "http-opportunistic" well-known URI
[RFC5785]. A client is said to have a valid http-opportunistic [RFC5785]. A client is said to have a valid http-opportunistic
response for a given origin when: response for a given origin when:
o The client has obtained a 200 (OK) response for the well-known URI o The client has requested the well-known URI from the origin over
from the origin, and it is fresh [RFC7234] (potentially through an authenticated connection and a 200 (OK) response was provided,
revalidation [RFC7232]), and and
o That response is fresh [RFC7234] (potentially through revalidation
[RFC7232]), and
o That response has the media type "application/json", and o That response has the media type "application/json", and
o That response's payload, when parsed as JSON [RFC7159], contains o That response's payload, when parsed as JSON [RFC7159], contains
an array as the root, and an array as the root, and
o The array contains a string that is a case-insensitive character- o The array contains a string that is a case-insensitive character-
for-character match for the origin in question, serialised into for-character match for the origin in question, serialised into
Unicode as per Section 6.1 of [RFC6454]. Unicode as per Section 6.1 of [RFC6454].
A client MAY treat an "http-opportunistic" resource as invalid if the A client MAY treat an "http-opportunistic" resource as invalid if
contains values that are not strings. values it contains are not strings.
This document does not define semantics for "http-opportunistic" This document does not define semantics for "http-opportunistic"
resources on an "https" origin, nor does it define semantics if the resources on an "https" origin, nor does it define semantics if the
resource includes "https" origins. resource includes "https" origins.
Allowing clients to cache the http-opportunistic resource means that
all alternative services need to be able to respond to requests for
"http" resources. A client is permitted to use an alternative
service without acquiring the http-opportunistic resource from that
service.
A client MUST NOT use any cached copies of an http-opportunistic
resource that was acquired (or revalidated) over an unauthenticated
connection. To avoid potential errors, a client can request or
revalidate the http-opportunistic resource before using any
connection to an alternative service.
Clients that use cached http-opportunistic responses MUST ensure that
their cache is cleared of any responses that were acquired over an
unauthenticated connection. Revalidating an unauthenticated response
using an authenticated connection does not ensure the integrity of
the response.
3. IANA Considerations 3. IANA Considerations
This specification registers a Well-Known URI [RFC5785]: This specification registers a Well-Known URI [RFC5785]:
o URI Suffix: http-opportunistic o URI Suffix: http-opportunistic
o Change Controller: IETF o Change Controller: IETF
o Specification Document(s): Section 2.3 of [this specification] o Specification Document(s): Section 2.3 of [this specification]
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