< draft-ietf-httpbis-http2-encryption-04.txt   draft-ietf-httpbis-http2-encryption-05.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: September 18, 2016 Mozilla Expires: December 2, 2016 Mozilla
March 17, 2016 May 31, 2016
Opportunistic Security for HTTP Opportunistic Security for HTTP
draft-ietf-httpbis-http2-encryption-04 draft-ietf-httpbis-http2-encryption-05
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 September 18, 2016. This Internet-Draft will expire on December 2, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
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5.1. Opportunistic Commitment . . . . . . . . . . . . . . . . 6 5.1. Opportunistic Commitment . . . . . . . . . . . . . . . . 6
5.2. Client Handling of A Commitment . . . . . . . . . . . . . 6 5.2. Client Handling of A Commitment . . . . . . . . . . . . . 6
5.3. Operational Considerations . . . . . . . . . . . . . . . 7 5.3. Operational Considerations . . . . . . . . . . . . . . . 7
6. The "http-opportunistic" well-known URI . . . . . . . . . . . 7 6. The "http-opportunistic" well-known URI . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8.1. Security Indicators . . . . . . . . . . . . . . . . . . . 8 8.1. Security Indicators . . . . . . . . . . . . . . . . . . . 8
8.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 8 8.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 8
8.3. Privacy Considerations . . . . . . . . . . . . . . . . . 9 8.3. Privacy Considerations . . . . . . . . . . . . . . . . . 9
8.4. Confusion Regarding Request Scheme . . . . . . . . . . . 9 8.4. Confusion Regarding Request Scheme . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.5. Server Controls . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
This document describes a use of HTTP Alternative Services This document describes a use of HTTP Alternative Services [RFC7838]
[I-D.ietf-httpbis-alt-svc] to decouple the URI scheme from the use to decouple the URI scheme from the use and configuration of
and configuration of underlying encryption, allowing a "http" URI underlying encryption, allowing a "http" URI [RFC7230] to be accessed
[RFC7230] to be accessed using TLS [RFC5246] opportunistically. using Transport Layer Security (TLS) [RFC5246] opportunistically.
Serving "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. This document describes a usage model whereby sites can difficult. This document describes a usage model whereby sites can
serve "http" URIs over TLS without being required to support strong serve "http" URIs over TLS without being required to support strong
server authentication. server authentication.
Opportunistic Security [RFC7435] does not provide the same guarantees Opportunistic Security [RFC7435] does not provide the same guarantees
as using TLS with "https" URIs; it is vulnerable to active attacks, as using TLS with "https" URIs; it is vulnerable to active attacks,
and does not change the security context of the connection. 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., Normally, users will not be able to tell 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 A mechanism for partially mitigating active attacks is described in
mechanism for partially mitigating them is described in Section 5. Section 5.
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.
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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 [RFC7838] for a protocol identifier that uses
identifier that uses TLS, such as "h2" [RFC7540]. 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 [RFC7838]).
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 can 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
[I-D.ietf-httpbis-alt-svc] requires that an alternative service only [RFC7838] requires that an alternative service only be used when
be used when there are "reasonable assurances" that it is under there are "reasonable assurances" that it is under control of and
control of and valid for the whole origin. valid for the whole origin.
As defined in that specification, one way of establishing this is As defined in that specification, a client can establish reasonable
using a TLS-based protocol with the certificate checks defined in assurances when using a TLS-based protocol with the certificate
[RFC2818]. Clients MAY impose additional criteria for establishing checks defined in [RFC2818].
reasonable assurances.
For the purposes of this specification, an additional way of For the purposes of this specification, an additional way of
establishing reasonable assurances is available when the alternative establishing reasonable assurances is available when the alternative
is on the same host as the origin, using the "http-opportunistic" is on the same host as the origin, using the "http-opportunistic"
well-known URI defined in Section 6. well-known URI defined in Section 6.
This allows deployment without the use of valid certificates, to This allows deployment without the use of valid certificates, to
encourage deployment of opportunistic security. When it is in use, encourage deployment of opportunistic security. When it is in use,
the alternative service can provide any certificate, or even select the alternative service can provide any certificate, or even select
TLS cipher suites that do not include authentication. TLS cipher suites that do not include authentication.
When the client has a valid http-opportunistic response for an When a client has a valid http-opportunistic response for an origin
origin, it MAY consider there to be reasonable assurances when: (as per Section 6), it MAY consider there to be reasonable assurances
as long as:
o The origin and alternative service's hostnames are the same when o The origin and alternative service's hostnames are the same when
compared in a case-insensitive fashion, and compared in a case-insensitive fashion, and
o The chosen alternative service returns the same response as above. o The origin object of the http-opportunistic response has a `tls-
ports' member, whose value is an array of numbers, one of which
matches the port of the alternative service in question, and
o The chosen alternative service returns the same representation as
the origin did for the http-opportunistic resource.
For example, this request/response pair would constitute reasonable For example, this request/response pair would constitute reasonable
assurances for the origin "http://www.example.com" for any assurances for the origin "http://www.example.com" for an alternative
alternative service also on "www.example.com": service on port 443 or 8000 of the host "www.example.com":
GET /.well-known/http-opportunistic HTTP/1.1 GET /.well-known/http-opportunistic HTTP/1.1
Host: www.example.com Host: www.example.com
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Connection: close Connection: close
{ {
"origins": ["http://example.com", "http://www.example.com:81"] "http://www.example.com": {
"tls-ports": [443, 8000]
}
} }
Note that this mechanism is only defined to establish reasonable Note that this mechanism is only defined to establish reasonable
assurances for the purposes of this specification; it does not apply assurances for the purposes of this specification; it does not apply
to other uses of alternative services unless they explicitly invoke to other uses of alternative services unless they explicitly invoke
it. it.
4. Interaction with "https" URIs 4. Interaction with "https" URIs
When using alternative services, requests for resources identified by When using alternative services, requests for resources identified by
both "http" and "https" URIs might use the same connection, because both "http" and "https" URIs might use the same connection, because
HTTP/2 permits requests for multiple 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. Section 2.1 of [RFC7838] 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)
suites), cannot be used for "https" URIs. cannot be used for "https" URIs.
5. Requiring Use of TLS 5. Requiring Use of TLS
Even when the alternative service is strongly authenticated, Even when the alternative service is strongly authenticated,
opportunistically upgrading cleartext HTTP connections to use TLS is opportunistically upgrading cleartext HTTP connections to use TLS is
subject to active attacks. In particular: subject to active attacks. In particular:
o Because the original HTTP connection is in cleartext, it is o Because the original HTTP connection is in cleartext, it is
vulnerable to man-in-the-middle attacks, and vulnerable to man-in-the-middle attacks, and
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When an origin is able to commit to providing service for a When an origin is able to commit to providing service for a
particular origin over TLS for a bounded period of time, clients can particular origin over TLS for a bounded period of time, clients can
choose to rely upon its availability, failing when it cannot be choose to rely upon its availability, failing when it cannot be
contacted. Effectively, this makes the choice to use a secured contacted. Effectively, this makes the choice to use a secured
protocol "sticky". protocol "sticky".
5.1. Opportunistic Commitment 5.1. Opportunistic Commitment
An origin can reduce the risk of attacks on opportunistically secured An origin can reduce the risk of attacks on opportunistically secured
connections by committing to provide an secured, authenticated connections by committing to provide a secured, authenticated
alternative service. This is done by including the optional "commit" alternative service. This is done by including the optional "tls-
member in the http-opportunistic well-known resource (see Section 6). commit" member in the origin object of the http-opportunistic well-
known response (see Section 6).
This feature is optional due to the requirement for server This feature is optional due to the requirement for server
authentication and the potential risk entailed (see Section 5.3). authentication and the potential risk entailed (see Section 5.3).
The value of the "commit" member is a number ([RFC7159], Section 6) The value of the "tls-commit" member is a number ([RFC7159],
indicating the duration of the commitment interval in seconds. Section 6) indicating the duration of the commitment interval in
seconds.
{ {
"origins": ["http://example.com", "http://www.example.com:81"], "http://www.example.com": {
"commit": 86400 "tls-ports": [443,8080],
"tls-commit": 3600
}
} }
Including "commit" creates a commitment to provide a secured Including "tls-commit" creates a commitment to provide a secured
alternative service for the advertised period. Clients that receive alternative service for the advertised period. Clients that receive
this commitment can assume that a secured alternative service will be this commitment can assume that a secured alternative service will be
available for the indicated period. Clients might however choose to available for the indicated period. Clients might however choose to
limit this time (see Section 5.3). limit this time (see Section 5.3).
5.2. Client Handling of A Commitment 5.2. Client Handling of A Commitment
The value of the "commit" member MUST be ignored unless the The value of the "tls-commit" member MUST be ignored unless the
alternative service can be strongly authenticated. The same alternative service can be strongly authenticated. The same
authentication requirements that apply to "https://" resources SHOULD authentication requirements that apply to "https://" resources SHOULD
be applied to authenticating the alternative. Minimum authentication be applied to authenticating the alternative. Minimum authentication
requirements for HTTP over TLS are described in Section 2.1 of requirements for HTTP over TLS are described in Section 2.1 of
[I-D.ietf-httpbis-alt-svc] and Section 3.1 of [RFC2818]. As noted in
[I-D.ietf-httpbis-alt-svc], clients can impose other checks in [RFC7838] and Section 3.1 of [RFC2818]. As noted in [RFC7838],
addition to this minimum set. For instance, a client might choose to clients can impose other checks in addition to this minimum set. For
apply key pinning [RFC7469]. instance, a client might choose to apply key pinning [RFC7469].
A client that receives a commitment and that successfully A client that receives a commitment and that successfully
authenticates the alternative service can assume that a secured authenticates the alternative service can assume that a secured
alternative will remain available for the commitment interval. The alternative will remain available for the commitment interval. The
commitment interval starts when the commitment is received and commitment interval starts when the commitment is received and
authenticated and runs for a number of seconds equal to value of the authenticated and runs for a number of seconds equal to value of the
"commit" member, less the current age of the http-opportunistic "tls-commit" member, less the current age of the http-opportunistic
response (as defined in Section 4.2.3 of [RFC7234]). A client SHOULD response (as defined in Section 4.2.3 of [RFC7234]). Note that the
avoid sending requests via cleartext protocols or to unauthenticated commitment interval MAY exceed the freshness lifetime of the "http-
alternative services for the duration of the commitment interval, opportunistic" resource.
except to discover new potential alternatives.
A commitment only applies to the origin of the http-opportunistic A client SHOULD avoid sending requests via cleartext protocols or to
well-known resource that was retrieved; other origins listed in the unauthenticated alternative services for the duration of the
"origins" member MUST be independently discovered and authenticated. commitment interval, except to discover new potential alternatives.
A commitment is not bound to a particular alternative service. A commitment is not bound to a particular alternative service.
Clients are able to use alternative services that they become aware Clients are able to use alternative services that they become aware
of. However, once a valid and authenticated commitment has been of. However, once a valid and authenticated commitment has been
received, clients SHOULD NOT use an unauthenticated alternative received, clients SHOULD NOT use an unauthenticated alternative
service. Where there is an active commitment, clients SHOULD ignore service. Where there is an active commitment, clients SHOULD ignore
advertisements for unsecured alternative services. A client MAY send advertisements for unsecured alternative services. A client MAY send
requests to an unauthenticated origin in an attempt to discover requests to an unauthenticated origin in an attempt to discover
potential alternative services, but these requests SHOULD be entirely potential alternative services, but these requests SHOULD be entirely
generic and avoid including credentials. generic and avoid including credentials.
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To avoid situations where a commitment causes errors, clients MAY To avoid situations where a commitment causes errors, clients MAY
limit the time over which a commitment is respected for a given limit the time over which a commitment is respected for a given
origin. A lower limit might be appropriate for initial commitments; origin. A lower limit might be appropriate for initial commitments;
the certainty that a site has set a correct value - and the the certainty that a site has set a correct value - and the
corresponding limit on persistence - might increase as a commitment corresponding limit on persistence - might increase as a commitment
is renewed multiple times. is renewed multiple times.
6. The "http-opportunistic" well-known URI 6. 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]. An origin is said to have a valid http-opportunistic [RFC5785]. A client is said to have a valid http-opportunistic
resource 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 obtained a 200 (OK) response for the well-known URI
from the origin, or refreshed one in cache [RFC7234], and from the origin, and it 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 object as the root. an object as the root.
o The "origins" member of the root object has a value of an array of o The root object contains a member whose name is a case-insensitive
strings, one of which is a case-insensitive character-for- character-for-character match for the origin in question,
character match for the origin in question, serialised into serialised into Unicode as per Section 6.1 of [RFC6454], and whose
Unicode as per [RFC6454], Section 6.1, and value is an object (hereafter, the "origin object").
This specification defines one additional, optional member of the
root object, "commit" in Section 5. Unrecognised members MUST be
ignored.
7. IANA Considerations 7. 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): [this specification] o Specification Document(s): Section 6 of [this specification]
o Related Information: o Related Information:
8. Security Considerations 8. Security Considerations
8.1. Security Indicators 8.1. 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., a "lock device"). used (e.g., a "lock device").
8.2. Downgrade Attacks 8.2. Downgrade Attacks
A downgrade attack against the negotiation for TLS is possible. With A downgrade attack against the negotiation for TLS is possible. With
commitment Section 5, this is limited to occasions where clients have commitment (see Section 5), this is limited to occasions where
no prior information (see Section 8.3), or when persisted commitments clients have no prior information (see Section 8.3), or when
have expired. persisted commitments have expired.
For example, because the "Alt-Svc" header field For example, because the "Alt-Svc" header field [RFC7838] likely
[I-D.ietf-httpbis-alt-svc] likely appears in an unauthenticated and appears in an unauthenticated and unencrypted channel, it is subject
unencrypted channel, it is subject to downgrade by network attackers. to downgrade by network attackers. In its simplest form, an attacker
In its simplest form, an attacker that wants the connection to remain that wants the connection to remain in the clear need only strip the
in the clear need only strip the "Alt-Svc" header field from "Alt-Svc" header field from responses.
responses.
Downgrade attacks can be partially mitigated using the "commit" Downgrade attacks can be partially mitigated using the "tls-commit"
member of the http-opportunistic well-known resource, because when it member of the http-opportunistic well-known resource, because when it
is used, a client can avoid using cleartext to contact a supporting is used, a client can avoid using cleartext to contact a supporting
server. However, this only works when a previous connection has been server. However, this only works when a previous connection has been
established without an active attacker present; a continuously established without an active attacker present; a continuously
present active attacker can either prevent the client from ever using present active attacker can either prevent the client from ever using
TLS, or offer its own certificate. TLS, or offer its own certificate.
8.3. Privacy Considerations 8.3. Privacy Considerations
Cached alternative services can be used to track clients over time; Cached alternative services can be used to track clients over time;
e.g., using a user-specific hostname. Clearing the cache reduces the e.g., using a user-specific hostname. Clearing the cache reduces the
ability of servers to track clients; therefore clients MUST clear ability of servers to track clients; therefore clients MUST clear
cached alternative service information when clearing other origin- cached alternative service information when clearing other origin-
based state (i.e., cookies). based state (i.e., cookies).
8.4. Confusion Regarding Request Scheme 8.4. Confusion Regarding Request Scheme
Many existing HTTP/1.1 implementations use the presence or absence of HTTP implementations and applications sometimes use ambient signals
TLS in the stack to determine whether requests are for "http" or to determine if a request is for an "https" resource; for example,
"https" resources. This is necessary in many cases because the most they might look for TLS on the stack, or a server port number of 443.
common form of an HTTP/1.1 request does not carry an explicit
indication of the URI scheme.
HTTP/1.1 MUST NOT be used for opportunistically secured requests. This might be due to limitations in the protocol (the most common
HTTP/1.1 request form does not carry an explicit indication of the
URI scheme), or it may be because how the server and application are
implemented (often, they are two separate entities, with a variety of
possible interfaces between them).
Some HTTP/1.1 implementations use ambient signals to determine if a Any security decisions based upon this information could be misled by
request is for an "https" resource. For example, implementations the deployment of this specification, because it violates the
might look for TLS on the stack or a port number of 443. An assumption that the use of TLS (or port 443) means that the client is
implementation that supports opportunistically secured requests accessing a HTTPS URI, and operating in the security context implied
SHOULD suppress these signals if there is any potential for by HTTPS.
confusion.
Therefore, servers need to carefully examine the use of such signals
before deploying this specification.
8.5. Server Controls
Because this specification allows "reasonable assurances" to be
established by the content of a well-known URI, servers SHOULD take
suitable measures to assure that its content remains under their
control. Likewise, because the Alt-Svc header field is used to
describe policies across an entire origin, servers SHOULD NOT permit
user content to set or modify the value of this header.
9. References 9. References
9.1. Normative References 9.1. Normative References
[I-D.ietf-httpbis-alt-svc]
mnot, m., McManus, P., and J. Reschke, "HTTP Alternative
Services", draft-ietf-httpbis-alt-svc-14 (work in
progress), March 2016.
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000, DOI 10.17487/RFC2818, May 2000,
<http://www.rfc-editor.org/info/rfc2818>. <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
skipping to change at page 10, line 32 skipping to change at page 10, line 41
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <http://www.rfc-editor.org/info/rfc7159>. 2014, <http://www.rfc-editor.org/info/rfc7159>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>. <http://www.rfc-editor.org/info/rfc7230>.
[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
DOI 10.17487/RFC7232, June 2014,
<http://www.rfc-editor.org/info/rfc7232>.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
RFC 7234, DOI 10.17487/RFC7234, June 2014, RFC 7234, DOI 10.17487/RFC7234, June 2014,
<http://www.rfc-editor.org/info/rfc7234>. <http://www.rfc-editor.org/info/rfc7234>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>. <http://www.rfc-editor.org/info/rfc7540>.
[RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP
Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
April 2016, <http://www.rfc-editor.org/info/rfc7838>.
9.2. Informative References 9.2. 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, DOI 10.17487/RFC7258, May Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <http://www.rfc-editor.org/info/rfc7258>. 2014, <http://www.rfc-editor.org/info/rfc7258>.
[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection [RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
Most of the Time", RFC 7435, DOI 10.17487/RFC7435, Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
December 2014, <http://www.rfc-editor.org/info/rfc7435>. December 2014, <http://www.rfc-editor.org/info/rfc7435>.
[RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning [RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April
2015, <http://www.rfc-editor.org/info/rfc7469>. 2015, <http://www.rfc-editor.org/info/rfc7469>.
Appendix A. Acknowledgements Appendix A. Acknowledgements
Thanks to Patrick McManus, Eliot Lear, Stephen Farrell, Guy Podjarny, Mike Bishop contributed significant text to this document.
Stephen Ludin, Erik Nygren, Paul Hoffman, Adam Langley, Eric Rescorla
and Richard Barnes for their feedback and suggestions. Thanks to Patrick McManus, Stefan Eissing, Eliot Lear, Stephen
Farrell, Guy Podjarny, Stephen Ludin, Erik Nygren, Paul Hoffman, Adam
Langley, Eric Rescorla, Julian Reschke, Kari Hurtta, and Richard
Barnes for their feedback and suggestions.
Authors' Addresses Authors' Addresses
Mark Nottingham Mark Nottingham
Email: mnot@mnot.net Email: mnot@mnot.net
URI: http://www.mnot.net/ URI: http://www.mnot.net/
Martin Thomson Martin Thomson
Mozilla Mozilla
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