HTTP Authentication Extensions for Interactive Clients
draft-ietf-httpauth-extension-09

[Ballot comment]
I agree with Stephen that this document must include the registration template as per Section 4.2.1 of BCP 90 (RFC 3864).

In Section 2.2:

    bare-token        = 1*(%x30-39 / %x41-5A / %x61-7A / "-" / "_")

Did you intent to allow leading "-" (and possibly "_") above?
As you are using "-." for private extensions,
I think the ABNF is not right. I think you meant:

    lead-token-char  = (%x30-39 / %x41-5A / %x61-7A / "_")
    bare-token        = lead-token-char *(%x30-39 / %x41-5A / %x61-7A / "-" / "_")


In Section 3, last paragraph:

  Support of this header is OPTIONAL; clients MAY also implement this
  extension only for some selected authentication schemes.  New
  authentication schemes can make support of the optional
  authentication mandatory by its specification, though.

I don't think this paragraph is needed, as this is granted, because support for any
extension like specified in this document is optional. So I suggest deleting it.


Section 3.1:

  I am still not convinced that Optional-WWW-Authenticate is needed,
  but the section provides a reasonable overview of the current situation.


In Section 4:

  Support of this header is OPTIONAL, and clients MAY choose any subset
  of these parameters to be supported.  The set of supported parameters
  MAY also be authentication scheme-dependent.  However, some
  authentication schemes can require mandatory/recommended support for
  some or all of the features provided in this header.

As above, I don't think this paragraph is needed.

4.4.  No-auth parameter

  This parameter SHOULD NOT be used along with the
  location-when-unauthenticated parameter.

Why is this only a SHOULD NOT (or to rephrase it: what are possible conditions for violating this)?

  If both were supplied,
  clients MAY choose which one is to be honored.

I would rather you pick one behaviour in order to improve interoperability.

In 4.5:

  When the user requests termination of an authentication period, and
  if the client currently displays a page supplied by a response with
  this parameter, the client will be redirected to the specified
  location by a new GET request (as if it received a 303 response).

Is this value advisory? Should the client go to this page automatically
or would the server redirect it? If the latter, why does this need to be told to the client?

  The log-out operation (e.g. erasing memories of user name,
  authentication credential and all related one-time credentials such
  as nonce or keys) SHOULD occur before processing a redirection.

4.6.  Logout-timeout parameter

  The parameter "logout-timeout", when contained in a successfully-
  authenticated response, means that any authentication credentials and
  state related to the current protection space are to be discarded if
  a time specified in this header (in seconds) has passed since from
  the time this header was received.  The value MUST be an integer.  As
  a special case, the value 0 means that the client is requested to
  immediately log-out from the current authentication space and revert
  to an unauthenticated status.

It sounds like this is not just a request, but the client will be logged out. If this is correct,
then you should reword this, for example:

  As a special case, the value 0 means that the server is logging the client
  out immediately from the current authentication space and that the client
  is now returns to unauthenticated state.

[Ballot comment]

I think experiments to improve web authentication are a good
thing (tm:-) so am happy to see this experiment proceed.

- Figure 1: Maybe clarify that "credentials" here is not the
same as in RFC 7235?

- Figure 3: this is a mixture of an example ("Basic") and ABNF
("1#challenge") which is odd. I'd say just make it an example
and fix the figure caption accordingly.

- section 7: I thought that registrations of new HTTP headers
needed some more information, e.g. in which messages they can
be sent and with which status codes? BCP90 does seem to call
for that - why aren't those details here?

[Ballot comment]
As mentioned by Rick Casarez in his OPS DIR review:

Section 3, paragraph 3:
Some sentence cleanup is required so that this remains clear. I believe I understand what is being said as far as implementation goes but some cleanup would make this paragraph more concise.

[Ballot comment]
1) The following disclarer is a little odd:

"The terms "encouraged" and "advised" are used for suggestions that do
  not constitute "SHOULD"-level requirements.  People MAY freely choose
  not to include the suggested items.  However, complying with those
  suggestions would be a best practice; it will improve the security,
  interoperability, and/or operational performance."

Both terms are only used once. I would recommend to remove the text above and simply use MAY later in the doc (or not use MAY and leave the later text as it is just without the disclaimer).

2) I agree that the section on username should point to the secturity section to give a clear warning. However, I also don't really understand why username is needed. If there is a good use case for it, maybe it's worth to explain this as another example.

[Ballot comment]
Comments from the Gen-ART reviewer Matt Miller should be taken into account, see below. I considered making a Discuss about the reference to Authentication-Info RFC but I trust that you guys will make the correct modifications. Thanks!

----

* There is at least a couple of mentions of the
"Authentication-Info" header, but no reference to RFC 7615 in which
it is defined.  I think an informational reference is warranted
here.

* Just reading sections 4.5. "Location-when-logout parameter" and
4.6. "Logout-timeout parameter", it is unclear how these are meant
to interact to inform a client the user's authentication session.
Frankly, I think the text in section 4.5 is too vague about how
a client can detect termination of a user's authenticated session,
and could use more of a hint on how "logout-timeout" is involved
to accomplish it. At the least, I think both sections 4.5. and
4.6. need pointers to section 5. to help readers get a
sense of how to apply them.

* In section 4.7. "Username parameter", I think there should be
an explicit pointer to the Security Considerations to warn about
potential issues this parameter presents.  I also recommend
separating that portion of the Security Considerations about
"username" into its own subsection to make such a callout
better.

* Since this document is acknowledging that cookies are used for
authentication, and

Nits/editorial comments:

* In section 2.1. "Terms for describing authentication protocol
flow", the word "distinguishable" should instead be "distinguished"
in the phrase "it can't be distinguishable from a non-authenticated
response."

* In section 3. "Optional Authentication", the word "be" is missing
in "Optional-WWW-Authenticate header MUST NOT sent on 401
responses".

* In section 3.1. "Note on Optional-WWW-Authenticate and use of
WWW-Authenticate header with non-401 status", the word "is" should
be replaced with "are" in the phrase "clients which is unaware of
this extension will ignore the header".

* Also in section 3.1., the word "authentications" should be
"authentication" in the phrase "secondary fallback method of
authentications".

* Also in section 3.1., the word "ignores" should be "ignore" in
the phrase "just ignores the WWW-Authenticate headers".

* Also in section 3.1., all instances of the word "implementer"
should be replaced with "implementers" in the phrase "the authors
propose implementer of the standard HTTP/1.1 specification
(especially implementer of this extension)".

* In section 4. "Authentication-Control header", the word "an"
should be "a" in the phrase "and MUST be sent in an plain".

* In section 4.1. "Non-ASCII extended header parameters", the
interoperability note as a number of grammatical challenges.
I believe the following addresses the grammar issues while
retaining its meaning:

  """
  Interoperability note: [RFC7235], Section 2.2, defines the "realm"
  authentication parameter which cannot be replaced by the "realm*"
  extend parameter.  It means that the use of non-ASCII values for an
  authentication realm is not the defined behavior in HTTP.
  Unfortunately, some people currently use a non-ASCII realm parameter
  in reality, but even its encoding scheme is not well-defined.
  Given this background, this document does not specify how to handle
  a non-ASCII "realm" parameter in the extended header fields.  If
  needed, the authors propose to use a non-extended "realm" parameter
  form, with a wish for maximum interoperability.
  """

* In section 4.2. "Auth-style parameter", the word "preferences"
should be replaced with "preference" in the phrase "server's
preferences for user interface behavior".

* In section .4.4. "No-auth parameter", the word "authentications"
should be replaced with "authentication" in the phrase "content is
desired before authentications".

* In section 4.6. "Logout-timeout parameter", the word "from" should
be removed in the phrase "has passed since from the time this header
was received".

* In section 5.3. "When to use Cookies", the first sentence has some
grammatical challenges, which I believe the following text addresses:

  """
  In current Web sites using form-based authentication, Cookies
  [RFC6265] are used for managing both authorization and
  application sessions.
  """

* In section 5.4. "Parallel deployment with Form/Cookie
authentications", the META tag example should be "" instead of ">META http-equiv="refresh"
...<".

* In section 7. "IANA Considerations", the word "documents" should
be "document" in the phrase "a publicly-accessible documents".

[Ballot comment]
In Section 2.2:

    bare-token        = 1*(%x30-39 / %x41-5A / %x61-7A / "-" / "_")

Did you intent to allow leading "-" (and possibly "_") above?
As you are using "-." for private extensions,
I think the ABNF is not right. I think you meant:

    lead-token-char  = (%x30-39 / %x41-5A / %x61-7A / "_")
    bare-token        = lead-token-char *(%x30-39 / %x41-5A / %x61-7A / "-" / "_")


In Section 3, last paragraph:

  Support of this header is OPTIONAL; clients MAY also implement this
  extension only for some selected authentication schemes.  New
  authentication schemes can make support of the optional
  authentication mandatory by its specification, though.

I don't think this paragraph is needed, as this is granted, because support for any
extension like specified in this document is optional. So I suggest deleting it.


Section 3.1:

  I am still not convinced that Optional-WWW-Authenticate is needed,
  but the section provides a reasonable overview of the current situation.


In Section 4:

  Support of this header is OPTIONAL, and clients MAY choose any subset
  of these parameters to be supported.  The set of supported parameters
  MAY also be authentication scheme-dependent.  However, some
  authentication schemes can require mandatory/recommended support for
  some or all of the features provided in this header.

As above, I don't think this paragraph is needed.

4.4.  No-auth parameter

  This parameter SHOULD NOT be used along with the
  location-when-unauthenticated parameter.

Why is this only a SHOULD NOT (or to rephrase it: what are possible conditions for violating this)?

  If both were supplied,
  clients MAY choose which one is to be honored.

I would rather you pick one behaviour in order to improve interoperability.

In 4.5:

  When the user requests termination of an authentication period, and
  if the client currently displays a page supplied by a response with
  this parameter, the client will be redirected to the specified
  location by a new GET request (as if it received a 303 response).

Is this value advisory? Should the client go to this page automatically
or would the server redirect it? If the latter, why does this need to be told to the client?

  The log-out operation (e.g. erasing memories of user name,
  authentication credential and all related one-time credentials such
  as nonce or keys) SHOULD occur before processing a redirection.

4.6.  Logout-timeout parameter

  The parameter "logout-timeout", when contained in a successfully-
  authenticated response, means that any authentication credentials and
  state related to the current protection space are to be discarded if
  a time specified in this header (in seconds) has passed since from
  the time this header was received.  The value MUST be an integer.  As
  a special case, the value 0 means that the client is requested to
  immediately log-out from the current authentication space and revert
  to an unauthenticated status.

It sounds like this is not just a request, but the client will be logged out. If this is correct,
then you should reword this, for example:

  As a special case, the value 0 means that the server is logging the client
  out immediately from the current authentication space and that the client
  is now returns to unauthenticated state.

(Via drafts-lastcall-comment@iana.org): IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-httpauth-extension-07.txt. If any part of this review is inaccurate, please let us know.

IANA has a question about one of the actions requested in the IANA Considerations section of [ RFC-to-be ].

IANA understands that, upon approval of [ RFC-to-be ], there are two actions which IANA must complete.

First, in the Permanent Message Header Field Names subregistry of the Message Headers registry located at:

https://www.iana.org/assignments/message-headers/message-headers.xhtml#perm-headers

two new header field names are to be registered as follows:

Header Field Name: Optional-WWW-Authenticate
Template:
Protocol: http
Status:
Reference: [ RFC-to-be ]

Header Field Name: Authentication-Control
Template:
Protocol: http
Status:
Reference: [ RFC-to-be ]

IANA Question --> what should be the value for "Status" for these two new header field names?

As [ RFC-to-be ] requests registrations in an Expert Review or Specification Required (see RFC 5226) registry, we will initiate the required Expert Review via a separate request. Expert review will need to be completed before your document can be approved for publication as an RFC.

Second, a new registry is to be created called the HTTP Authentication Control Parameters registry.

IANA QUESTION -> Where should this new registry be located? Is it a néw registry on the List of all IANA maintained protocol parameter registries or is it a subregistry of an existing registry? If it is a subregistry of an existing registry, in which registry will it be contained?

The new registry is to be managed via Specification Required as defined in RFC5226.

There are initial entries in this new registry as follows:

+-------------------------------+------------------------------+
| Token | Specification |
+-------------------------------+------------------------------+
| auth-style | Section 4.2 of [ RFC-to-be ] |
| location-when-unauthenticated | Section 4.3 of [ RFC-to-be ] |
| no-auth | Section 4.4 of [ RFC-to-be ] |
| location-when-logout | Section 4.5 of [ RFC-to-be ] |
| logout-timeout | Section 4.6 of [ RFC-to-be ] |
| username | Section 4.7 of [ RFC-to-be ] |
+-------------------------------+------------------------------+

IANA understands that these are the only actions required to be completed upon approval of [ RFC-to-be ].

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed. 


Thank you,

Sabrina Tanamal
IANA Specialist
ICANN

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: "Yoav Nir" , ynir.ietf@gmail.com, httpauth-chairs@ietf.org, Kathleen.Moriarty.ietf@gmail.com, http-auth@ietf.org, draft-ietf-httpauth-extension@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (HTTP Authentication Extensions for Interactive Clients) to Experimental RFC


The IESG has received a request from the Hypertext Transfer Protocol
Authentication WG (httpauth) to consider the following document:
- 'HTTP Authentication Extensions for Interactive Clients'
  as Experimental RFC

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2016-08-26. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  This document specifies extensions for the HTTP authentication
  framework for interactive clients.  Currently, fundamental features
  of HTTP-level authentication are insufficient for complex
  requirements of various Web-based applications.  This forces these
  applications to implement their own authentication frameworks by
  means like HTML forms, which becomes one of the hurdles against
  introducing secure authentication mechanisms handled jointly by
  servers and user-agent.  The extended framework fills gaps between
  Web application requirements and HTTP authentication provisions to
  solve the above problems, while maintaining compatibility with
  existing Web and non-Web uses of HTTP authentications.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-httpauth-extension/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-httpauth-extension/ballot/


No IPR declarations have been submitted directly on this I-D.

Authors are Yutaka Oiwa, Hajime Watanabe, Hiromitsu Takagi, Tatsuya
Hayashi and Yuichi Ioku. Kathleen Moriarty is the responsible Area
Director. Yoav Nir is the document shepherd.

Summary
  This document specifies extensions for the HTTP authentication
  framework for interactive clients.  Currently, fundamental features
  of HTTP-level authentication are insufficient for complex
  requirements of various Web-based applications.  This forces these
  applications to implement their own authentication frameworks by
  means like HTML forms, which becomes one of the hurdles against
  introducing secure authentication mechanisms handled jointly by
  servers and user-agent.  The extended framework fills gaps between
  Web application requirements and HTTP authentication provisions to
  solve the above problems, while maintaining compatibility with
  existing Web and non-Web uses of HTTP authentications.
 
Review and Consensus
  This document is one in a three-part set of documents describing the
  Mutual-Auth authentication method for HTTP. This part extends the HTTP
  authentication framework from RFC 7235 to include optional
  authentication as well as de-authorization (log out) and finer control
  of redirection depending on authentication status.

  With version -07 it is the consensus of the HTTP-Auth working group
  that this document is fit to be published as an experimental RFC.
  The document received a moderate amount of review from the working
  group. In addition we solicited and received a review from Cory
  Benfield.
 
  There are implementations of this protocol written by the authors.
  They take the form of a modified web server and a fork of the Firefox
  browser that include this functionality.
 
Intellectual Property
  All authors have confirmed that they are not aware of any undisclosed
  IPR associated with this document. There have been no IPR disclosures.
 
Other Issues
  None