Opportunistic Security for HTTP/2
RFC 8164
Internet Engineering Task Force (IETF) M. Nottingham
Request for Comments: 8164
Category: Experimental M. Thomson
ISSN: 2070-1721 Mozilla
May 2017
Opportunistic Security for HTTP/2
Abstract
This document describes how "http" URIs can be accessed using
Transport Layer Security (TLS) and HTTP/2 to mitigate pervasive
monitoring attacks. This mechanism not a replacement for "https"
URIs; it is vulnerable to active attacks.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for examination, experimental implementation, and
evaluation.
This document defines an Experimental Protocol for the Internet
community. 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). Not
all documents approved by the IESG are a candidate for any level of
Internet Standard; see 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/rfc8164.
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.
Nottingham & Thomson Experimental [Page 1]
RFC 8164 Opportunistic HTTP/2 Security May 2017
Table of Contents
1. Introduction ....................................................2
1.1. Goals and Non-goals ........................................3
1.2. Notational Conventions .....................................3
2. Using HTTP URIs over TLS ........................................3
2.1. Alternative Server Opt-In ..................................4
2.2. Interaction with "https" URIs ..............................5
2.3. The "http-opportunistic" Well-Known URI ....................5
3. IANA Considerations .............................................6
4. Security Considerations .........................................7
4.1. Security Indicators ........................................7
4.2. Downgrade Attacks ..........................................7
4.3. Privacy Considerations .....................................7
4.4. Confusion regarding Request Scheme .........................7
4.5. Server Controls ............................................8
5. References ......................................................8
5.1. Normative References .......................................8
5.2. Informative References .....................................9
Acknowledgements ...................................................9
Authors' Addresses ................................................10
1. Introduction
This document describes a use of HTTP Alternative Services [RFC7838]
to decouple the URI scheme from the use and configuration of
underlying encryption. It allows an "http" URI [RFC7230] to be
accessed using HTTP/2 and Transport Layer Security (TLS) [RFC5246]
with Opportunistic Security [RFC7435].
This document describes a usage model whereby sites can serve "http"
URIs over TLS, thereby avoiding the problem of serving Mixed Content
(described in [W3C.CR-mixed-content-20160802]) while still providing
protection against passive attacks.
Opportunistic Security does not provide the same guarantees as using
TLS with "https" URIs, because it is vulnerable to active attacks,
and does not change the security context of the connection.
Normally, users will not be able to tell that it is in use (i.e.,
there will be no "lock icon").
Nottingham & Thomson Experimental [Page 2]
RFC 8164 Opportunistic HTTP/2 Security May 2017
1.1. Goals and Non-goals
The immediate goal is to make the use of HTTP more robust in the face
of pervasive passive monitoring [RFC7258].
A secondary (but significant) goal is to provide for ease of
implementation, deployment, and operation. This mechanism is
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