draft-ietf-httpbis-http2-encryption-01.txt   draft-ietf-httpbis-http2-encryption-02.txt 
HTTPbis 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 18, 2015 Mozilla Expires: December 17, 2015 Mozilla
December 15, 2014 June 15, 2015
Opportunistic Security for HTTP Opportunistic Security for HTTP
draft-ietf-httpbis-http2-encryption-01 draft-ietf-httpbis-http2-encryption-02
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.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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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 18, 2015. This Internet-Draft will expire on December 17, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2015 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
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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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Table of Contents Table of Contents
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
3. Server Authentication . . . . . . . . . . . . . . . . . . . . 4 3. Server Authentication . . . . . . . . . . . . . . . . . . . . 4
4. Interaction with "https" URIs . . . . . . . . . . . . . . . . 4 4. Interaction with "https" URIs . . . . . . . . . . . . . . . . 4
5. Requiring Use of TLS . . . . . . . . . . . . . . . . . . . . 5 5. Requiring Use of TLS . . . . . . . . . . . . . . . . . . . . 5
5.1. The HTTP-TLS Header Field . . . . . . . . . . . . . . . . 5 5.1. The HTTP-TLS Header Field . . . . . . . . . . . . . . . . 5
5.2. Operational Considerations . . . . . . . . . . . . . . . 6 5.2. Operational Considerations . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6.1. Security Indicators . . . . . . . . . . . . . . . . . . . 7 6.1. Security Indicators . . . . . . . . . . . . . . . . . . . 7
6.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 7 6.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 7
6.3. Privacy Considerations . . . . . . . . . . . . . . . . . 7 6.3. Privacy Considerations . . . . . . . . . . . . . . . . . 8
6.4. Confusion Regarding Request Scheme . . . . . . . . . . . 8 6.4. Confusion Regarding Request Scheme . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8 7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9 7.2. 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 This document describes a use of HTTP Alternative Services
[I-D.ietf-httpbis-alt-svc] to decouple the URI scheme from the use [I-D.ietf-httpbis-alt-svc] to decouple the URI scheme from the use
and configuration of underlying encryption, allowing a "http" URI to and configuration of underlying encryption, allowing a "http" URI to
be accessed using TLS [RFC5246] opportunistically. be accessed using TLS [RFC5246] opportunistically.
Currently, "https" URIs require acquiring and configuring a valid Serving "https" URIs require acquiring and configuring a valid
certificate, which means that some deployments find supporting TLS certificate, which means that some deployments find supporting TLS
difficult. Therefore, this document describes a usage model whereby difficult. This document describes a usage model whereby sites can
sites can serve "http" URIs over TLS without being required to serve "http" URIs over TLS without being required to support strong
support strong server authentication. server authentication.
Opportunistic Security [I-D.dukhovni-opportunistic-security] does not Opportunistic Security [RFC7435] does not provide the same guarantees
provide the same guarantees as using TLS with "https" URIs; it is as using TLS with "https" URIs; it is vulnerable to active attacks,
vulnerable to active attacks, and does not change the security and does not change the security context of the connection.
context of the connection. Normally, users will not be able to tell Normally, users will not be able to tell that it is in use (i.e.,
that it is in use (i.e., there will be no "lock icon"). there will be no "lock icon").
By its nature, this technique is vulnerable to active attacks. A By its nature, this technique is vulnerable to active attacks. A
mechanism for partially mitigating them is described in Section 5. mechanism for partially mitigating them is described in Section 5.
It does not offer the same level of protection as afforded to "https"
URIs, but increases the likelihood that an active attack be detected.
1.1. Goals and Non-Goals 1.1. Goals and Non-Goals
The immediate goal is to make the use of HTTP more robust in the face The immediate goal is to make the use of HTTP more robust in the face
of pervasive passive monitoring [RFC7258]. of pervasive passive monitoring [RFC7258].
A secondary goal is to limit the potential for active attacks. It is A secondary goal is to limit the potential for active attacks. It is
not intended to offer the same level of protection as afforded to not intended to offer the same level of protection as afforded to
"https" URIs, but instead to increase the likelihood that an active "https" URIs, but instead to increase the likelihood that an active
attack can be detected. attack can be detected.
A final (but significant) goal is to provide for ease of A final (but significant) goal is to provide for ease of
implementation, deployment and operation. This mechanism should have implementation, deployment and operation. This mechanism is expected
a minimal impact upon performance, and should not require extensive to have a minimal impact upon performance, and a trivial
administrative effort to configure. administrative effort to configure.
1.2. Notational Conventions 1.2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Using HTTP URIs over TLS 2. Using HTTP URIs over TLS
An origin server that supports the resolution of "http" URIs can An origin server that supports the resolution of "http" URIs can
indicate support for this specification by providing an alternative indicate support for this specification by providing an alternative
service advertisement [I-D.ietf-httpbis-alt-svc] for a protocol service advertisement [I-D.ietf-httpbis-alt-svc] for a protocol
identifier that uses TLS, such as "h2" [I-D.ietf-httpbis-http2]. identifier that uses TLS, such as "h2" [RFC7540].
A client that receives such an advertisement MAY make future requests A client that receives such an advertisement MAY make future requests
intended for the associated origin ([RFC6454]) to the identified intended for the associated origin ([RFC6454]) to the identified
service (as specified by [I-D.ietf-httpbis-alt-svc]). service (as specified by [I-D.ietf-httpbis-alt-svc]).
A client that places the importance of protection against passive A client that places the importance of protection against passive
attacks over performance might choose to withhold requests until an attacks over performance might choose to withhold requests until an
encrypted connection is available. However, if such a connection encrypted connection is available. However, if such a connection
cannot be successfully established, the client MAY resume its use of cannot be successfully established, the client can resume its use of
the cleartext connection. the cleartext connection.
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.
3. Server Authentication 3. Server Authentication
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operational challenges. For these reasons, server authentication is operational challenges. For these reasons, server authentication is
not mandatory for "http" URIs when using the mechanism described in not mandatory for "http" URIs when using the mechanism described in
this specification. this specification.
When connecting to an alternative service for an "http" URI, clients When connecting to an alternative service for an "http" URI, clients
are not required to perform the server authentication procedure are not required to perform the server authentication procedure
described in Section 3.1 of [RFC2818]. The server certificate, if described in Section 3.1 of [RFC2818]. The server certificate, if
one is proffered by the alternative service, is not necessarily one is proffered by the alternative service, is not necessarily
checked for validity, expiration, issuance by a trusted certificate checked for validity, expiration, issuance by a trusted certificate
authority or matched against the name in the URI. Therefore, the authority or matched against the name in the URI. Therefore, the
alternative service MAY provide any certificate, or even select TLS alternative service can provide any certificate, or even select TLS
cipher suites that do not include authentication. cipher suites that do not include authentication.
A client MAY perform additional checks on the offered certificate if A client MAY perform additional checks on the offered certificate if
the server does not select an unauthenticated TLS cipher suite. This the server does not select an unauthenticated TLS cipher suite. This
document doesn't define any such checks, though clients could be document doesn't define any such checks, though clients could be
configured with a policy that defines what is acceptable. configured with a policy that defines what is acceptable.
As stipulated by [I-D.ietf-httpbis-alt-svc], clients MUST NOT use As stipulated by [I-D.ietf-httpbis-alt-svc], clients MUST NOT use
alternative services with a host other than the origin's, unless the alternative services with a host other than the origin's, unless the
alternative service itself is strongly authenticated (as the origin's alternative service itself is strongly authenticated (as the origin's
host); for example, using TLS with a certificate that validates as host); for example, using TLS with a certificate that validates as
per [RFC2818]. per [RFC2818].
4. Interaction with "https" URIs 4. Interaction with "https" URIs
When using alternative services, both "http" and "https" URIs might When using alternative services, requests for resources identified by
use the same connection, because HTTP/2 permits requests for multiple both "http" and "https" URIs might use the same connection, because
origins on the same connection. HTTP/2 permits requests for multiple origins on the same connection.
Since "https" URIs rely on server authentication, a connection that Since "https" URIs rely on server authentication, a connection that
is initially created for "http" URIs without authenticating the is initially created for "http" URIs without authenticating the
server cannot be used for "https" URIs until the server certificate server cannot be used for "https" URIs until the server certificate
is successfully authenticated. Section 3.1 of [RFC2818] describes is successfully authenticated. Section 3.1 of [RFC2818] describes
the basic mechanism, though the authentication considerations in the basic mechanism, though the authentication considerations in
[I-D.ietf-httpbis-alt-svc] also apply. [I-D.ietf-httpbis-alt-svc] also apply.
Connections that are established without any means of server Connections that are established without any means of server
authentication (for instance, the purely anonymous TLS cipher authentication (for instance, the purely anonymous TLS cipher
suites), cannot be used for "https" URIs. suites), cannot be used for "https" URIs.
5. Requiring Use of TLS 5. Requiring Use of TLS
Editors' Note: this is a very rough take on an approach that would Editors' Note: this is a very rough take on an approach that would
provide a limited form of protection against downgrade attack. It's provide a limited form of protection against downgrade attack. It's
unclear at this point whether the additional effort (and modest unclear at this point whether the additional effort (and modest
operational cost) is worthwhile. operational cost) is worthwhile.
The mechanism described in this specification is trival to mount an The mechanism described in this specification is trivial to mount an
active attack against, for two reasons: active attack against, for two reasons:
o A client that doesn't perform authentication an easy victim of o A client that doesn't perform authentication is an easy victim of
server impersonation, through man-in-the-middle attacks. server impersonation, through man-in-the-middle attacks.
o A client that is willing to use cleartext to resolve the resource o A client that is willing to use HTTP over cleartext to resolve the
will do so if access to any TLS-enabled alternative services is resource will do so if access to any TLS-enabled alternative
blocked at the network layer. services is blocked at the network layer.
Given that the primary goal of this specification is to prevent Given that the primary goal of this specification is to prevent
passive attacks, these are not critical failings (especially passive attacks, these are not critical failings (especially
considering the alternative - HTTP over cleartext). However, a considering the alternative - HTTP over cleartext). However, a
modest form of protection against active attacks can be provided for modest form of protection against active attacks can be provided for
clients on subsequent connections. clients on subsequent connections.
When an alternative service is able to commit to providing service When an alternative service is able to commit to providing service
for a particular origin over TLS for a bounded period of time, for a particular origin over TLS for a bounded period of time,
clients can choose to rely upon its avilability, failing when it clients can choose to rely upon its availability, failing when it
cannot be contacted. Effectively, this makes the choice to use a cannot be contacted. Effectively, this makes the choice to use a
secured protocol "sticky" in the client. secured protocol "sticky" in the client.
5.1. The HTTP-TLS Header Field 5.1. The HTTP-TLS Header Field
A alternative service can make this commitment by sending a "HTTP- A alternative service can make this commitment by sending a "HTTP-
TLS" header field: TLS" header field, described here using the '#' ABNF extension
defined in Section 7 of [RFC7230]:
HTTP-TLS = 1#parameter HTTP-TLS = 1#parameter
When it appears in a HTTP response from a strongly authenticated When it appears in a HTTP response from a strongly authenticated
alternative service, this header field indicates that the alternative service, this header field indicates that the
availability of the origin through TLS-protected alternative services availability of the origin through TLS-protected alternative services
is "sticky", and that the client MUST NOT fall back to cleartext is "sticky", and that the client MUST NOT fall back to cleartext
protocols while this information is considered fresh. protocols while this information is considered fresh.
For example: For example:
GET /index.html HTTP/1.1 GET /index.html HTTP/1.1
Host: example.com Host: example.com
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: text/html Content-Type: text/html
Cache-Control: 600 Cache-Control: max-age=600
Age: 30 Age: 30
Date: Thu, 1 May 2014 16:20:09 GMT Date: Thu, 1 May 2014 16:20:09 GMT
HTTP-TLS: ma=3600 HTTP-TLS: ma=3600
This header field creates a commitment from the origin [RFC6454] of This header field creates a commitment from the origin [RFC6454] of
the associated resource (in the example, "http://example.com"). For the associated resource (in the example, "http://example.com"). For
the duration of the commitment, clients SHOULD strongly authenticate the duration of the commitment, clients SHOULD strongly authenticate
the server for all subsequent requests made to that origin, though the server for all subsequent requests made to that origin, though
this creates some risks for clients Section 5.2. this creates some risks for clients (see Section 5.2).
Authentication for HTTP over TLS is described in Section 3.1 of Authentication for HTTP over TLS is described in Section 3.1 of
[RFC2818], noting the additional requirements in [RFC2818], noting the additional requirements in Section 2.1 of
[I-D.ietf-httpbis-alt-svc]. The header field MUST be ignored if [I-D.ietf-httpbis-alt-svc]. The header field MUST be ignored if
strong authentication fails; otherwise, an attacker could create a strong authentication fails; otherwise, an attacker could create a
persistent denial of service by falsifying a commitment. persistent denial of service by falsifying a commitment.
The commitment to use authenticated TLS persists for a period The commitment to use authenticated TLS persists for a period
determined by the value of the "ma" parameter. See Section 4.2.3 of determined by the value of the "ma" parameter. See Section 4.2.3 of
[RFC7234] for details of determining response age. [RFC7234] for details of determining response age.
ma-parameter = delta-seconds ma-parameter = delta-seconds
The commitment made by the "HTTP-TLS" header field applies only to The commitment made by the "HTTP-TLS" header field applies only to
the origin of the resource that generates the "HTTP-TLS" header the origin of the resource that generates the "HTTP-TLS" header
field. Requests for an origin that has a persisted, unexpired value field.
for "HTTP-TLS" MUST fail if they cannot be made over an authenticated
TLS connection. Requests for an origin that has a persisted, unexpired value for
"HTTP-TLS" MUST fail if they cannot be made over an authenticated TLS
connection.
Note that the commitment is not bound to a particular alternative Note that the commitment is not bound to a particular alternative
service. Clients SHOULD use alternative services that they become service. Clients SHOULD use alternative services that they become
aware of. However, clients MUST NOT use an unauthenticated aware of. However, clients MUST NOT use an unauthenticated
alternative service for an origin with this commitment. Where there alternative service for an origin with this commitment. Where there
is an active commitment, clients MAY instead ignore advertisements is an active commitment, clients MAY instead ignore advertisements
for unsecured alternatives services. for unsecured alternatives services.
5.2. Operational Considerations 5.2. Operational Considerations
To avoid situations where a persisted value of "HTTP-TLS" causes a To avoid situations where a persisted value of "HTTP-TLS" causes a
client to be unable to contact a site, clients SHOULD limit the time client to be unable to contact a site, clients SHOULD limit the time
that a value is persisted for a given origin. A lower limit might be that a value is persisted for a given origin. A lower limit might be
appropriate for initial observations of "HTTP-TLS"; the certainty appropriate for initial observations of "HTTP-TLS"; the certainty
that a site has set a correct value - and the corresponding limit on that a site has set a correct value - and the corresponding limit on
persistence - can increase as the value is seen more over time. persistence - can increase as the value is seen more over time.
Once a server has indicated that it will support authenticated TLS, a Once a server has indicated that it will support authenticated TLS, a
client MAY use key pinning [I-D.ietf-websec-key-pinning] or any other client MAY use key pinning [RFC7469] or any other mechanism that
mechanism that would otherwise be restricted to use with "https" would otherwise be restricted to use with "https" URIs, provided that
URIs, provided that the mechanism can be restricted to a single HTTP the mechanism can be restricted to a single HTTP origin.
origin.
6. Security Considerations 6. Security Considerations
6.1. Security Indicators 6.1. Security Indicators
User Agents MUST NOT provide any special security indicia when an User Agents MUST NOT provide any special security indicia when an
"http" resource is acquired using TLS. In particular, indicators "http" resource is acquired using TLS. In particular, indicators
that might suggest the same level of security as "https" MUST NOT be that might suggest the same level of security as "https" MUST NOT be
used (e.g., using a "lock device"). used (e.g., using a "lock device").
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based state (i.e., cookies). based state (i.e., cookies).
6.4. Confusion Regarding Request Scheme 6.4. Confusion Regarding Request Scheme
Many existing HTTP/1.1 implementations use the presence or absence of Many existing HTTP/1.1 implementations use the presence or absence of
TLS in the stack to determine whether requests are for "http" or TLS in the stack to determine whether requests are for "http" or
"https" resources. This is necessary in many cases because the most "https" resources. This is necessary in many cases because the most
common form of an HTTP/1.1 request does not carry an explicit common form of an HTTP/1.1 request does not carry an explicit
indication of the URI scheme. indication of the URI scheme.
HTTP/1.1 MUST NOT be sent over HTTP/1.1 or earlier versions of the HTTP/1.1 MUST NOT be used for opportunistically secured requests.
protocol. Opportunistically secured HTTP requests MUST include an
explicit scheme identifier.
7. References 7. References
7.1. Normative References 7.1. Normative References
[I-D.ietf-httpbis-alt-svc] [I-D.ietf-httpbis-alt-svc]
Nottingham, M., McManus, P., and J. Reschke, "HTTP mnot, m., McManus, P., and J. Reschke, "HTTP Alternative
Alternative Services", draft-ietf-httpbis-alt-svc-05 (work Services", draft-ietf-httpbis-alt-svc-07 (work in
in progress), December 2014. progress), May 2015.
[I-D.ietf-httpbis-http2]
Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
Protocol version 2", draft-ietf-httpbis-http2-16 (work in
progress), November 2014.
[I-D.ietf-websec-key-pinning]
Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
Extension for HTTP", draft-ietf-websec-key-pinning-21
(work in progress), October 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/
RFC2818, May 2000,
<http://www.rfc-editor.org/info/rfc2818>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/
RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, December [RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, DOI 10
2011. .17487/RFC6454, December 2011,
<http://www.rfc-editor.org/info/rfc6454>.
[RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10
.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7234] Fielding, R., Nottingham, M., and J. Reschke, "Hypertext [RFC7234] Fielding, R., Nottingham, M., and J. Reschke, "Hypertext
Transfer Protocol (HTTP/1.1): Caching", RFC 7234, June Transfer Protocol (HTTP/1.1): Caching", RFC 7234, DOI 10
2014. .17487/RFC7234, June 2014,
<http://www.rfc-editor.org/info/rfc7234>.
7.2. Informative References [RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April
2015, <http://www.rfc-editor.org/info/rfc7469>.
[I-D.dukhovni-opportunistic-security] [RFC7540] Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
Dukhovni, V., "Opportunistic Security: Some Protection Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/
Most of the Time", draft-dukhovni-opportunistic- RFC7540, May 2015,
security-06 (work in progress), November 2014. <http://www.rfc-editor.org/info/rfc7540>.
7.2. Informative References
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an [RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
Attack", BCP 188, RFC 7258, May 2014. Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <http://www.rfc-editor.org/info/rfc7258>.
[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
December 2014, <http://www.rfc-editor.org/info/rfc7435>.
Appendix A. Acknowledgements Appendix A. Acknowledgements
Thanks to Patrick McManus, Eliot Lear, Stephen Farrell, Guy Podjarny, Thanks to Patrick McManus, Eliot Lear, Stephen Farrell, Guy Podjarny,
Stephen Ludin, Erik Nygren, Paul Hoffman, Adam Langley, Eric Rescorla Stephen Ludin, Erik Nygren, Paul Hoffman, Adam Langley, Eric Rescorla
and Richard Barnes for their feedback and suggestions. and Richard Barnes for their feedback and suggestions.
Authors' Addresses Authors' Addresses
Mark Nottingham Mark Nottingham
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