[Technical Errata Reported] RFC7235 (6307)

[RFC Errata System <[e-mail]>]

The following errata report has been submitted for RFC7235,
"Hypertext Transfer Protocol (HTTP/1.1): Authentication".

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You may review the report below and at:
https://www.rfc-editor.org/errata/eid6307

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Type: Technical
Reported by: Nick Cullen <[e-mail]>

Section: 2.1

Original Text
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2.1.  Challenge and Response

   HTTP provides a simple challenge-response authentication framework
   that can be used by a server to challenge a client request and by a
   client to provide authentication information.  It uses a case-
   insensitive token as a means to identify the authentication scheme,
   followed by additional information necessary for achieving
   authentication via that scheme.  The latter can be either a comma-
   separated list of parameters or a single sequence of characters
   capable of holding base64-encoded information.

   Authentication parameters are name=value pairs, where the name token
   is matched case-insensitively, and each parameter name MUST only
   occur once per challenge.

     auth-scheme    = token

     auth-param     = token BWS "=" BWS ( token / quoted-string )


Corrected Text
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2.1.  Challenge and Response

   HTTP provides a simple challenge-response authentication framework
   that can be used by a server to challenge a client request and by a
   client to provide authentication information.  It uses a case-
   insensitive token as a means to identify the authentication scheme,
   followed by additional information necessary for achieving
   authentication via that scheme.  The latter can be either a comma-
   separated list of parameters or a single sequence of characters
   capable of holding base64-encoded information.

   Authentication parameters are name=value pairs, where the name token
   is matched case-insensitively, and each parameter name MUST only
   occur once per challenge.

     auth-scheme    = itoken

     auth-param     = itoken BWS "=" BWS ( token / quoted-string )

N.B. itoken is a restricted subset of token to ensure well defined case insensitivity.


Notes
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The general token specification allows many characters (including VCHAR) which means that case insensitivity is tricky to define. A more limited subset of token would be sensible, and the distinction between itoken and token is important in understanding the BNF, and matching that to the specification. The section above is a good example of the confusion that can arise, with 3 instances of token in the ABNF, but two of them are to be interpreted in a different way than the third occurence..
Confusion causes incompatibility with NEGOTIATE being rejected by a system that implements the ABNF, but wrongly expects Negotiate.
P.S. My 'corrected text' and my understanding of ABNF are incomplete. I crave assistance in forming a properly written definition of itoken to 'well define' the safe subset.

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RFC7235 (draft-ietf-httpbis-p7-auth-26)
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Title               : Hypertext Transfer Protocol (HTTP/1.1): Authentication
Publication Date    : June 2014
Author(s)           : R. Fielding, Ed., J. Reschke, Ed.
Category            : PROPOSED STANDARD
Source              : Hypertext Transfer Protocol Bis APP
Area                : Applications
Stream              : IETF
Verifying Party     : IESG