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Versions: 00 01 02 03 04 05 06 07 08 draft-ietf-httpauth-basicauth-update

Network Working Group                                         J. Reschke
Internet-Draft                                                greenbytes
Updates: 2617 (if approved)                                  May 8, 2013
Intended status: Experimental
Expires: November 9, 2013


          An Encoding Parameter for HTTP Basic Authentication
                     draft-reschke-basicauth-enc-08

Abstract

   The "Basic" authentication scheme defined in RFC 2617 does not
   properly define how to treat non-ASCII characters.  This has lead to
   a situation where user agent implementations disagree, and servers
   make different assumptions based on the locales they are running in.
   There is little interoperability for the non-ASCII characters in the
   ISO-8859-1 character set, and even less interoperability for any
   characters beyond that.

   This document defines a backwards-compatible extension to "Basic",
   specifying the server's character encoding expectation, using a new
   authentication scheme parameter.

Editorial Note (To be removed by RFC Editor before publication)

   Distribution of this document is unlimited.  Although this is not a
   work item of the HTTPAUTH Working Group, comments should be sent to
   the HTTPAUTH WG's mailing list at http-auth@ietf.org [1], which may
   be joined using the form at
   <https://www.ietf.org/mailman/listinfo/http-auth>.

   Discussions of the HTTPAUTH Working Group are archived at <http://
   www.ietf.org/mail-archive/web/http-auth/current/maillist.html>.

   XML versions, latest edits and the issues list for this document are
   available from
   <http://greenbytes.de/tech/webdav/#draft-reschke-basicauth-enc>.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.



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   Internet-Drafts are draft documents valid for a maximum of six months
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Notational Conventions . . . . . . . . . . . . . . . . . . . .  4
   3.  The 'accept-charset' auth-param  . . . . . . . . . . . . . . .  4
   4.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  5
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  5
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     8.1.  Normative References . . . . . . . . . . . . . . . . . . .  6
     8.2.  Informative References . . . . . . . . . . . . . . . . . .  7
   Appendix A.  Deployment Considerations . . . . . . . . . . . . . .  7
     A.1.  User Agents  . . . . . . . . . . . . . . . . . . . . . . .  7
       A.1.1.  Alternative approach . . . . . . . . . . . . . . . . .  7
     A.2.  Origin Servers . . . . . . . . . . . . . . . . . . . . . .  8
   Appendix B.  FAQ (to be removed by RFC Editor before
                publication)  . . . . . . . . . . . . . . . . . . . .  8
     B.1.  Why not simply switch the default encoding to UTF-8? . . .  8
     B.2.  What about Digest? . . . . . . . . . . . . . . . . . . . .  8
     B.3.  Will existing UAs ignore the parameter?  . . . . . . . . .  8
   Appendix C.  Change Log (to be removed by RFC Editor before
                publication)  . . . . . . . . . . . . . . . . . . . .  8
     C.1.  Since draft-reschke-basicauth-enc-00 . . . . . . . . . . .  8
     C.2.  Since draft-reschke-basicauth-enc-01 . . . . . . . . . . .  9
     C.3.  Since draft-reschke-basicauth-enc-02 . . . . . . . . . . .  9
     C.4.  Since draft-reschke-basicauth-enc-03 . . . . . . . . . . .  9
     C.5.  Since draft-reschke-basicauth-enc-04 . . . . . . . . . . .  9
     C.6.  Since draft-reschke-basicauth-enc-05 . . . . . . . . . . .  9
     C.7.  Since draft-reschke-basicauth-enc-06 . . . . . . . . . . .  9
     C.8.  Since draft-reschke-basicauth-enc-07 . . . . . . . . . . .  9
   Appendix D.  Open issues (to be removed by RFC Editor prior to
                publication)  . . . . . . . . . . . . . . . . . . . .  9
     D.1.  edit . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     D.2.  unorm  . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     D.3.  terminology  . . . . . . . . . . . . . . . . . . . . . . . 10
     D.4.  parmname2831 . . . . . . . . . . . . . . . . . . . . . . . 10














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1.  Introduction

   The "Basic" authentication scheme defined in Section 2 of [RFC2617]
   does not properly define how to treat non-ASCII characters
   ([USASCII]): it uses the Base64 ([RFC4648], Section 4) encoding of
   the concatenation of username, separator character, and password
   without stating which character encoding to use.

   This has lead to a situation where user agent implementations
   disagree, and servers make different assumptions based on the locales
   they are running in.  There is little interoperability for the non-
   ASCII characters in the ISO-8859-1 character set ([USASCII],
   [ISO-8859-1]), and even less interoperability for any characters
   beyond that.

   This document defines a backwards-compatible extension to "Basic",
   specifying the server's character encoding expectation, using a new
   auth-param for use in the Proxy-Authenticate and WWW-Authenticate
   header fields, as defined in [draft-ietf-httpbis-p7-auth].

2.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  The 'accept-charset' auth-param

   In challenges, servers MAY use the "accept-charset" authentication
   parameter (case-insensitive) to express the character encoding they
   expect the user agent to use.

   The only allowed value is "UTF-8", to be matched case-insensitively
   (see [RFC2978], Section 2.3), indicating that the server expects the
   UTF-8 character encoding to be used ([RFC3629]).

   Other values are reserved for future use.

      Note: The 'accept-charset' parameter cannot be included when
      sending credentials (e.g. in the Authorization or Proxy-
      Authorization header fields), as the "Basic" scheme uses a single
      token for credentials ('token68' syntax), not a parameter list
      ('#auth-param' syntax); see Section 2.1 of
      [draft-ietf-httpbis-p7-auth].







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4.  Examples

   In the example below, the server prompts for authentication in the
   "foo" realm, using Basic authentication, with a preference for the
   UTF-8 character encoding:

   WWW-Authenticate: Basic realm="foo", accept-charset="UTF-8"

   Note that the parameter value can be either a token or a quoted
   string; in this case the server chose to use the quoted-string
   notation.

   The user's name is "test", and his password is the string "123"
   followed by the Unicode character U+00A3 (POUND SIGN).  Following
   Section 1.2 of [RFC2617], but using the character encoding UTF-8, the
   user-pass, converted to a sequence of octets, is:

    't' 'e' 's' 't' ':' '1' '2' '3' pound
    74  65  73  74  3A  31  32  33  C2  A3

   Encoding this octet sequence in Base64 ([RFC4648], Section 4) yields:

     dGVzdDoxMjPCow==

   Thus the Authorization header field would be:

     Authorization: Basic dGVzdDoxMjPCow==

   Or, for proxy authentication:

     Proxy-Authorization: Basic dGVzdDoxMjPCow==

5.  Security Considerations

   This document does not introduce any new security considerations
   beyond those defined for the "Basic" authentication scheme
   ([RFC2617], Section 4), and those applicable to the handling of UTF-8
   ([RFC3629], Section 10).

6.  IANA Considerations

   There are no IANA Considerations related to this specification.

7.  Acknowledgements

   The internationalisation problem has been reported as a Mozilla bug
   back in the year 2000 (see
   <https://bugzilla.mozilla.org/show_bug.cgi?id=41489> and also the



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   more recent <https://bugzilla.mozilla.org/show_bug.cgi?id=656213>).
   It was Andrew Clover's idea to address it using a new auth-param.

   Thanks to Bjoern Hoehrmann, Amos Jeffries, James Manger, and Martin
   Thomson for providing feedback on this document.

8.  References

8.1.  Normative References

   [ISO-8859-1]                  International Organization for
                                 Standardization, "Information
                                 technology -- 8-bit single-byte coded
                                 graphic character sets -- Part 1: Latin
                                 alphabet No. 1", ISO/IEC 8859-1:1998,
                                 1998.

   [RFC2119]                     Bradner, S., "Key words for use in RFCs
                                 to Indicate Requirement Levels",
                                 BCP 14, RFC 2119, March 1997.

   [RFC2617]                     Franks, J., Hallam-Baker, P.,
                                 Hostetler, J., Lawrence, S., Leach, P.,
                                 Luotonen, A., and L. Stewart, "HTTP
                                 Authentication: Basic and Digest Access
                                 Authentication", RFC 2617, June 1999.

   [RFC2978]                     Freed, N. and J. Postel, "IANA Charset
                                 Registration Procedures", BCP 19,
                                 RFC 2978, October 2000.

   [RFC3629]                     Yergeau, F., "UTF-8, a transformation
                                 format of ISO 10646", STD 63, RFC 3629,
                                 November 2003.

   [USASCII]                     American National Standards Institute,
                                 "Coded Character Set -- 7-bit American
                                 Standard Code for Information
                                 Interchange", ANSI X3.4, 1986.

   [draft-ietf-httpbis-p7-auth]  Fielding, R., Ed. and J. Reschke, Ed.,
                                 "Hypertext Transfer Protocol
                                 (HTTP/1.1): Authentication",
                                 draft-ietf-httpbis-p7-auth-22 (work in
                                 progress), February 2013.






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8.2.  Informative References

   [RFC4648]                     Josefsson, S., "The Base16, Base32, and
                                 Base64 Data Encodings", RFC 4648,
                                 October 2006.

   [XHR]                         Aubourg, J., Song, J., and H. Steen,
                                 "XMLHttpRequest", W3C Working Draft WD-
                                 XMLHttpRequest-20121206, December 2012,
                                 <http://www.w3.org/TR/2012/
                                 WD-XMLHttpRequest-20121206/>.

                                 Latest version available at
                                 <http://www.w3.org/TR/XMLHttpRequest/>.

URIs

   [1]  <mailto:http-auth@ietf.org>

Appendix A.  Deployment Considerations

A.1.  User Agents

   User agents not implementing this specifications should continue to
   work as before, ignoring the new parameter.

   User agents which already default to the UTF-8 encoding implement
   this specification by definition.  Note that some user agents also
   have different defaults depending on whether the request originates
   from page navigation as opposed to a script-driven request using
   XMLHttpRequest [XHR].

   Other user agents can keep their default behavior, and switch to
   UTF-8 when seeing the new parameter.

A.1.1.  Alternative approach

   On the other hand, the strategy below may already improve the user-
   visible behavior today:

   o  In the first authentication request, choose the character encoding
      based on the user's credentials: if they do not need any
      characters outside the ISO-8859-1 character set, default to ISO-
      8859-1, otherwise use UTF-8.

   o  If the first attempt failed and the encoding used was ISO-8859-1,
      retry once with UTF-8 encoding instead.




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   Note that there's a risk if the site blocks an account after multiple
   login failures (for instance, when it doesn't reset the counter after
   a successful login).

A.2.  Origin Servers

   Origin servers that do not support non-ASCII characters in
   credentials do not require any changes.

   Origin servers that need to support non-ASCII characters, but can't
   use the UTF-8 encoding will not be affected; they will continue to
   function as well as before.

   Finally, origin servers that need to support non-ASCII characters and
   can use the UTF-8 encoding can opt in as described above.  In the
   worst case, they'll continue to see either broken credentials or no
   credentials at all (depending on how legacy clients handle characters
   they can not encode).

Appendix B.  FAQ (to be removed by RFC Editor before publication)

B.1.  Why not simply switch the default encoding to UTF-8?

   There are sites in use today that default to a locale encoding, such
   as ISO-8859-1, and expect user agents to use that encoding.  These
   sites will break if the user agent uses a different encoding, such as
   UTF-8.

B.2.  What about Digest?

   Although the solution proposed in this document may be applicable to
   "Digest" as well, any attempt to update this scheme may be an uphill
   battle hard to win.

B.3.  Will existing UAs ignore the parameter?

   It appears they will.  See
   <http://greenbytes.de/tech/tc/httpauth/#simplebasicnewparam1> and
   <http://greenbytes.de/tech/tc/httpauth/#simplebasicnewparam2>.

Appendix C.  Change Log (to be removed by RFC Editor before publication)

C.1.  Since draft-reschke-basicauth-enc-00

   Add and close issues "credparam" and "paramcase".  Rewrite the
   deployment considerations.





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C.2.  Since draft-reschke-basicauth-enc-01

   Note more recent Mozilla bugzilla entry; add behavior of existing UAs
   to FAQ (with pointer to test cases).

C.3.  Since draft-reschke-basicauth-enc-02

   Add and resolve issue "xhrutf8".

C.4.  Since draft-reschke-basicauth-enc-03

   Add and resolve issue "proxy".

C.5.  Since draft-reschke-basicauth-enc-04

   Add and resolve issues "paramname" and "sentparam".  Add issues
   "terminology" and "unorm".  Update HTTPbis reference.

C.6.  Since draft-reschke-basicauth-enc-05

   Update HTTPbis reference.

C.7.  Since draft-reschke-basicauth-enc-06

   Update HTTPbis and XHR references.

C.8.  Since draft-reschke-basicauth-enc-07

   "b64token" -> "token68" (ABNF term changed in HTTPbis P7).  Change
   contact information from HTTPbis WG to HTTPAUTH WG.  Add issue
   parmname2831.  Changed intended status to "experimental".

Appendix D.  Open issues (to be removed by RFC Editor prior to
             publication)

D.1.  edit

   Type: edit

   julian.reschke@greenbytes.de (2010-08-11): Umbrella issue for
   editorial fixes/enhancements.

D.2.  unorm

   Type: edit

   julian.reschke@greenbytes.de (2012-02-02): We need a statement about
   unicode normalization forms.



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D.3.  terminology

   Type: edit

   julian.reschke@greenbytes.de (2012-02-02): Try to be consistent with
   the terminology defined in RFC 6365.

D.4.  parmname2831

   In Section 3:

   Type: change

   julian.reschke@greenbytes.de (2012-05-08): RFC 2831 (Digest SASL
   Mechanism) defines a *very* similar parameter but calls it "charset".
   We may want to be consistent with that.

Author's Address

   Julian F. Reschke
   greenbytes GmbH
   Hafenweg 16
   Muenster, NW  48155
   Germany

   EMail: julian.reschke@greenbytes.de
   URI:   http://greenbytes.de/tech/webdav/
























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