draft-ietf-httpauth-basicauth-update-06.txt   draft-ietf-httpauth-basicauth-update-07.txt 
HTTPAuth Working Group J. Reschke HTTPAuth Working Group J. Reschke
Internet-Draft greenbytes Internet-Draft greenbytes
Obsoletes: 2617 (if approved) February 12, 2015 Obsoletes: 2617 (if approved) February 28, 2015
Intended status: Standards Track Intended status: Standards Track
Expires: August 16, 2015 Expires: September 1, 2015
The 'Basic' HTTP Authentication Scheme The 'Basic' HTTP Authentication Scheme
draft-ietf-httpauth-basicauth-update-06 draft-ietf-httpauth-basicauth-update-07
Abstract Abstract
This document defines the "Basic" Hypertext Transfer Protocol (HTTP) This document defines the "Basic" Hypertext Transfer Protocol (HTTP)
Authentication Scheme, which transmits credentials as user-id/ Authentication Scheme, which transmits credentials as user-id/
password pairs, encoded using Base64. password pairs, encoded using Base64.
Editorial Note (To be removed by RFC Editor before publication) Editorial Note (To be removed by RFC Editor before publication)
Discussion of this draft takes place on the HTTPAuth working group Discussion of this draft takes place on the HTTPAuth working group
mailing list (http-auth@ietf.org), which is archived at <http:// mailing list (http-auth@ietf.org), which is archived at <http://
www.ietf.org/mail-archive/web/http-auth/current/maillist.html>. www.ietf.org/mail-archive/web/http-auth/current/maillist.html>.
XML versions, latest edits and the issues list for this document are XML versions, latest edits and the issues list for this document are
available from <http://greenbytes.de/tech/ available from <http://greenbytes.de/tech/
webdav/#draft-ietf-httpauth-basicauth-update>. webdav/#draft-ietf-httpauth-basicauth-update>.
The changes in this draft are summarized in Appendix C.7. The changes in this draft are summarized in Appendix C.8.
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 16, 2015. This Internet-Draft will expire on September 1, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2015 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
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publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 3, line 8 skipping to change at page 3, line 8
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4 1.1. Terminology and Notation . . . . . . . . . . . . . . . . . 4
1.1.1. Syntax Notation . . . . . . . . . . . . . . . . . . . 4
2. The 'Basic' Authentication Scheme . . . . . . . . . . . . . . 4 2. The 'Basic' Authentication Scheme . . . . . . . . . . . . . . 4
2.1. The 'charset' auth-param . . . . . . . . . . . . . . . . . 6 2.1. The 'charset' auth-param . . . . . . . . . . . . . . . . . 6
2.2. Re-using Credentials . . . . . . . . . . . . . . . . . . . 8 2.2. Re-using Credentials . . . . . . . . . . . . . . . . . . . 8
3. Internationalization Considerations . . . . . . . . . . . . . 8 3. Internationalization Considerations . . . . . . . . . . . . . 8
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Normative References . . . . . . . . . . . . . . . . . . . 11 7.1. Normative References . . . . . . . . . . . . . . . . . . . 11
7.2. Informative References . . . . . . . . . . . . . . . . . . 11 7.2. Informative References . . . . . . . . . . . . . . . . . . 12
Appendix A. Changes from RFC 2617 . . . . . . . . . . . . . . . . 12 Appendix A. Changes from RFC 2617 . . . . . . . . . . . . . . . . 13
Appendix B. Deployment Considerations for the 'charset' Appendix B. Deployment Considerations for the 'charset'
Parameter . . . . . . . . . . . . . . . . . . . . . . 13 Parameter . . . . . . . . . . . . . . . . . . . . . . 13
B.1. User Agents . . . . . . . . . . . . . . . . . . . . . . . 13 B.1. User Agents . . . . . . . . . . . . . . . . . . . . . . . 13
B.2. Origin Servers . . . . . . . . . . . . . . . . . . . . . . 13 B.2. Servers . . . . . . . . . . . . . . . . . . . . . . . . . 13
B.3. Why not simply switch the default encoding to UTF-8? . . . 13 B.3. Why not simply switch the default encoding to UTF-8? . . . 14
Appendix C. Change Log (to be removed by RFC Editor before Appendix C. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 13 publication) . . . . . . . . . . . . . . . . . . . . 14
C.1. Since RFC 2617 . . . . . . . . . . . . . . . . . . . . . . 14 C.1. Since RFC 2617 . . . . . . . . . . . . . . . . . . . . . . 14
C.2. Since draft-ietf-httpauth-basicauth-update-00 . . . . . . 14 C.2. Since draft-ietf-httpauth-basicauth-update-00 . . . . . . 14
C.3. Since draft-ietf-httpauth-basicauth-update-01 . . . . . . 14 C.3. Since draft-ietf-httpauth-basicauth-update-01 . . . . . . 15
C.4. Since draft-ietf-httpauth-basicauth-update-02 . . . . . . 14 C.4. Since draft-ietf-httpauth-basicauth-update-02 . . . . . . 15
C.5. Since draft-ietf-httpauth-basicauth-update-03 . . . . . . 14 C.5. Since draft-ietf-httpauth-basicauth-update-03 . . . . . . 15
C.6. Since draft-ietf-httpauth-basicauth-update-04 . . . . . . 15 C.6. Since draft-ietf-httpauth-basicauth-update-04 . . . . . . 15
C.7. Since draft-ietf-httpauth-basicauth-update-05 . . . . . . 15 C.7. Since draft-ietf-httpauth-basicauth-update-05 . . . . . . 15
C.8. Since draft-ietf-httpauth-basicauth-update-06 . . . . . . 15
1. Introduction 1. Introduction
This document defines the "Basic" Hypertext Transfer Protocol (HTTP) This document defines the "Basic" Hypertext Transfer Protocol (HTTP)
Authentication Scheme, which transmits credentials as user-id/ Authentication Scheme, which transmits credentials as user-id/
password pairs, encoded using Base64 (HTTP authentication schemes are password pairs, encoded using Base64 (HTTP authentication schemes are
defined in [RFC7235]). defined in [RFC7235]).
This scheme is not considered to be a secure method of user This scheme is not considered to be a secure method of user
authentication unless used in conjunction with some external secure authentication unless used in conjunction with some external secure
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user-id and password are passed over the network as cleartext. user-id and password are passed over the network as cleartext.
The "Basic" scheme previously was defined in Section 2 of [RFC2617]. The "Basic" scheme previously was defined in Section 2 of [RFC2617].
This document updates the definition, and also addresses This document updates the definition, and also addresses
internationalization issues by introducing the "charset" internationalization issues by introducing the "charset"
authentication parameter (Section 2.1). authentication parameter (Section 2.1).
Other documents updating RFC 2617 are "Hypertext Transfer Protocol Other documents updating RFC 2617 are "Hypertext Transfer Protocol
(HTTP/1.1): Authentication" ([RFC7235], defining the authentication (HTTP/1.1): Authentication" ([RFC7235], defining the authentication
framework), "HTTP Digest Access Authentication" ([DIGEST], updating framework), "HTTP Digest Access Authentication" ([DIGEST], updating
the definition of the '"Digest" authentication scheme), and "The the definition of the "Digest" authentication scheme), and "The
Hypertext Transfer Protocol (HTTP) Authentication-Info and Proxy- Hypertext Transfer Protocol (HTTP) Authentication-Info and Proxy-
Authentication-Info Response Header Fields" ([AUTHINFO]). Taken Authentication-Info Response Header Fields" ([AUTHINFO]). Taken
together, these four documents obsolete RFC 2617. together, these four documents obsolete RFC 2617.
1.1. Notational Conventions 1.1. Terminology and Notation
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].
1.1.1. Syntax Notation
This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234].
The terms protection space and realm are defined in Section 2.2 of The terms protection space and realm are defined in Section 2.2 of
[RFC7235]. [RFC7235].
The terms (character) repertoire and character encoding scheme are The terms (character) repertoire and character encoding scheme are
defined in Section 2 of [RFC6365]. defined in Section 2 of [RFC6365].
2. The 'Basic' Authentication Scheme 2. The 'Basic' Authentication Scheme
The "Basic" authentication scheme is based on the model that the The "Basic" authentication scheme is based on the model that the
client needs to authenticate itself with a user-id and a password for client needs to authenticate itself with a user-id and a password for
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WWW-Authenticate: Basic realm="WallyWorld" WWW-Authenticate: Basic realm="WallyWorld"
...where "WallyWorld" is the string assigned by the server to ...where "WallyWorld" is the string assigned by the server to
identify the protection space. identify the protection space.
A proxy can respond with a similar challenge using the 407 (Proxy A proxy can respond with a similar challenge using the 407 (Proxy
Authentication Required) status code ([RFC7235], Section 3.2) and the Authentication Required) status code ([RFC7235], Section 3.2) and the
Proxy-Authenticate header field ([RFC7235], Section 4.3). Proxy-Authenticate header field ([RFC7235], Section 4.3).
To receive authorization, the client To receive authorization, the client
1. obtains the user-id and password from the user, 1. obtains the user-id and password from the user,
2. constructs the user-pass by concatenating user-id, a single colon 2. constructs the user-pass by concatenating the user-id, a single
(":") character, and the password, colon (":") character, and the password,
3. encodes the user-pass into an octet sequence (see below for a 3. encodes the user-pass into an octet sequence (see below for a
discussion of character encoding schemes), discussion of character encoding schemes),
4. and obtains the basic-credentials by encoding this octet sequence 4. and obtains the basic-credentials by encoding this octet sequence
using base64 ([RFC4648], Section 4) into a sequence of US-ASCII using base64 ([RFC4648], Section 4) into a sequence of US-ASCII
characters ([RFC0020]). characters ([RFC0020]).
The original definition of this authentication scheme failed to The original definition of this authentication scheme failed to
specify the character encoding scheme used to convert the user-pass specify the character encoding scheme used to convert the user-pass
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either a locale-specific encoding such as ISO-8859-1 ([ISO-8859-1]), either a locale-specific encoding such as ISO-8859-1 ([ISO-8859-1]),
or UTF-8 ([RFC3629]). For backwards compatibility reasons, this or UTF-8 ([RFC3629]). For backwards compatibility reasons, this
specification continues to leave the default encoding undefined, as specification continues to leave the default encoding undefined, as
long as it is compatible with US-ASCII (mapping any US-ASCII long as it is compatible with US-ASCII (mapping any US-ASCII
character to a single octet matching the US-ASCII character code). character to a single octet matching the US-ASCII character code).
The user-id and password MUST NOT contain any control characters (see The user-id and password MUST NOT contain any control characters (see
"CTL" in Appendix B.1 of [RFC5234]). "CTL" in Appendix B.1 of [RFC5234]).
Furthermore, a user-id containing a colon character is invalid, as Furthermore, a user-id containing a colon character is invalid, as
recipients will split the user-pass at the first occurrence of a the first colon in a user-pass string separates user-id and password
colon character. Note that many user agents however will accept a from one another; text after the first colon is part of the password.
colon in user-id, thereby producing a user-pass string that User-ids containing colons cannot be encoded in user-pass strings.
recipients will likely treat in a way not intended by the user.
Note that many user agents produce user-pass strings without checking
that user-ids supplied by users do not contain colons; recipients
will then treat part of the username input as part of the password.
If the user agent wishes to send the user-id "Aladdin" and password If the user agent wishes to send the user-id "Aladdin" and password
"open sesame", it would use the following header field: "open sesame", it would use the following header field:
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ== Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
2.1. The 'charset' auth-param 2.1. The 'charset' auth-param
In challenges, servers can use the "charset" authentication parameter In challenges, servers can use the "charset" authentication parameter
to indicate the character encoding scheme they expect the user agent to indicate the character encoding scheme they expect the user agent
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For the user-id, recipients MUST support all characters defined in For the user-id, recipients MUST support all characters defined in
the "UsernameCasePreserved" profile defined in in Section 3.3 of the "UsernameCasePreserved" profile defined in in Section 3.3 of
[PRECIS], with the exception of the colon (":") character. [PRECIS], with the exception of the colon (":") character.
For the password, recipients MUST support all characters defined in For the password, recipients MUST support all characters defined in
the "OpaqueString" profile defined in in Section 4.2 of [PRECIS]. the "OpaqueString" profile defined in in Section 4.2 of [PRECIS].
Other values are reserved for future use. Other values are reserved for future use.
Note: The 'charset' is only defined on challenges, as "Basic" uses Note: The 'charset' is only defined on challenges, as "Basic" uses
a single token for credentials ('token68' syntax), thus the a single token for credentials ('token68' syntax); thus the
credentials syntax isn't extensible. credentials syntax isn't extensible.
Note: The name 'charset' has been chosen for consistency with Note: The name 'charset' has been chosen for consistency with
Section 2.1.1 of [RFC2831]. A better name would have been Section 2.1.1 of [RFC2831]. A better name would have been
'accept-charset', as it is not about the message it appears in, 'accept-charset', as it is not about the message it appears in,
but the server's expectation. but the server's expectation.
In the example below, the server prompts for authentication in the In the example below, the server prompts for authentication in the
"foo" realm, using Basic authentication, with a preference for the "foo" realm, using Basic authentication, with a preference for the
UTF-8 character encoding scheme: UTF-8 character encoding scheme:
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Proxy-Authorization: Basic dGVzdDoxMjPCow== Proxy-Authorization: Basic dGVzdDoxMjPCow==
2.2. Re-using Credentials 2.2. Re-using Credentials
Given the absolute URI ([RFC3986], Section 4.3) of an authenticated Given the absolute URI ([RFC3986], Section 4.3) of an authenticated
request, the authentication scope of that request is obtained by request, the authentication scope of that request is obtained by
removing all characters after the last slash ("/") character of the removing all characters after the last slash ("/") character of the
path component ("hier_part", see [RFC3986], Section 3). A client path component ("hier_part", see [RFC3986], Section 3). A client
SHOULD assume that resources identified by URIs with a prefix-match SHOULD assume that resources identified by URIs with a prefix-match
of the authentication scope are also within the protection space of the authentication scope are also within the protection space
specified by the realm value of the that authenticated request. specified by the realm value of that authenticated request.
A client MAY preemptively send the corresponding Authorization header A client MAY preemptively send the corresponding Authorization header
field with requests for resources in that space without receipt of field with requests for resources in that space without receipt of
another challenge from the server. Similarly, when a client sends a another challenge from the server. Similarly, when a client sends a
request to a proxy, it may reuse a user-id and password in the Proxy- request to a proxy, it MAY reuse a user-id and password in the Proxy-
Authorization header field without receiving another challenge from Authorization header field without receiving another challenge from
the proxy server. the proxy server.
For example, given an authenticated request to: For example, given an authenticated request to:
http://example.com/docs/index.html http://example.com/docs/index.html
...requests to the URIs below could use the known credentials: ...requests to the URIs below could use the known credentials:
http://example.com/docs/ http://example.com/docs/
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User-ids or passwords containing characters outside the US-ASCII User-ids or passwords containing characters outside the US-ASCII
character repertoire will cause interoperability issues, unless both character repertoire will cause interoperability issues, unless both
communication partners agree on what character encoding scheme is to communication partners agree on what character encoding scheme is to
be used. Servers can use the new 'charset' parameter (Section 2.1) be used. Servers can use the new 'charset' parameter (Section 2.1)
to indicate a preference of "UTF-8", increasing the probability that to indicate a preference of "UTF-8", increasing the probability that
clients will switch to that encoding. clients will switch to that encoding.
The "realm" parameter carries data that can be considered textual, The "realm" parameter carries data that can be considered textual,
however [RFC7235] does not define a way to reliably transport non-US- however [RFC7235] does not define a way to reliably transport non-US-
ASCII characters. This is a known issue that would need to be ASCII characters. This is a known issue that would need to be
addressed in that specification. addressed in a revision to that specification.
4. Security Considerations 4. Security Considerations
The Basic authentication scheme is not a secure method of user The Basic authentication scheme is not a secure method of user
authentication, nor does it in any way protect the entity, which is authentication, nor does it in any way protect the entity, which is
transmitted in cleartext across the physical network used as the transmitted in cleartext across the physical network used as the
carrier. HTTP does not prevent the addition of enhancements (such as carrier. HTTP does not prevent the addition of enhancements (such as
schemes to use one-time passwords) to Basic authentication. schemes to use one-time passwords) to Basic authentication.
The most serious flaw in Basic authentication is that it results in The most serious flaw in Basic authentication is that it results in
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The danger arises because naive users frequently reuse a single The danger arises because naive users frequently reuse a single
password to avoid the task of maintaining multiple passwords. password to avoid the task of maintaining multiple passwords.
If a server permits users to select their own passwords, then the If a server permits users to select their own passwords, then the
threat is not only unauthorized access to documents on the server but threat is not only unauthorized access to documents on the server but
also unauthorized access to any other resources on other systems that also unauthorized access to any other resources on other systems that
the user protects with the same password. Furthermore, in the the user protects with the same password. Furthermore, in the
server's password database, many of the passwords may also be users' server's password database, many of the passwords may also be users'
passwords for other sites. The owner or administrator of such a passwords for other sites. The owner or administrator of such a
system could therefore expose all users of the system to the risk of system could therefore expose all users of the system to the risk of
unauthorized access to all those sites if this information is not unauthorized access to all those other sites if this information is
maintained in a secure fashion. This raises both security and not maintained in a secure fashion. This raises both security and
privacy concerns ([RFC6973]). If the same user-id and password privacy concerns ([RFC6973]). If the same user-id and password
combination is in use to access other accounts, such as an email or combination is in use to access other accounts, such as an email or
health portal account, personal information could be exposed. health portal account, personal information could be exposed.
Basic Authentication is also vulnerable to spoofing by counterfeit Basic authentication is also vulnerable to spoofing by counterfeit
servers. If a user can be led to believe that he is connecting to a servers. If a user can be led to believe that she is connecting to a
host containing information protected by Basic authentication when, host containing information protected by Basic authentication when,
in fact, he is connecting to a hostile server or gateway, then the in fact, she is connecting to a hostile server or gateway, then the
attacker can request a password, store it for later use, and feign an attacker can request a password, store it for later use, and feign an
error. This type of attack is not possible with Digest error. Server implementers ought to guard against this sort of
Authentication. Server implementers SHOULD guard against the counterfeiting; in particular, software components which can take
possibility of this sort of counterfeiting by gateways or CGI over control over the message framing on an existing connection (for
scripts. In particular it is very dangerous for a server to simply instance, "NPH" ("non parsing of headers") scripts) need to be used
turn over a connection to a gateway. That gateway can then use the carefully or not at all.
persistent connection mechanism to engage in multiple transactions
with the client while impersonating the original server in a way that
is not detectable by the client.
The use of the UTF-8 character encoding scheme introduces additional Servers and proxies implementing Basic Authentication need to store
security considerations; see Section 10 of [RFC3629] for more user passwords in some form in order to authenticate a request.
information. These passwords ought to be be stored in such a way that a leak of
the password data doesn't make them trivially recoverable. This is
especially important when users are allowed to set their own
passwords, since users are known to choose weak passwords and to
reuse them across authentication realms. While a full discussion of
good password hashing techniques is beyond the scope of this
document, server operators ought to make an effort to minimize risks
to their users in the event of a password data leak. For example,
servers ought to avoid storing user passwords in plaintext or as
unsalted digests. For more discussion about modern password hashing
techniques, see the "Password Hashing Competition"
(<https://password-hashing.net>).
The use of the UTF-8 character encoding scheme and of normalization
introduces additional security considerations; see Section 10 of
[RFC3629] and Section 6 of [RFC5198] for more information.
5. IANA Considerations 5. IANA Considerations
IANA maintains the registry of HTTP Authentication Schemes IANA maintains the registry of HTTP Authentication Schemes
([RFC7235]) at <http://www.iana.org/assignments/http-authschemes>. ([RFC7235]) at <http://www.iana.org/assignments/http-authschemes>.
The entry for the "Basic" Authentication Scheme shall be updated with The entry for the "Basic" Authentication Scheme shall be updated by
a pointer to this specification. replacing the reference with a pointer to this specification.
6. Acknowledgements 6. Acknowledgements
This specification takes over the definition of the "Basic" HTTP This specification takes over the definition of the "Basic" HTTP
Authentication Scheme, previously defined in RFC 2617. We thank John Authentication Scheme, previously defined in RFC 2617. We thank John
Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D. Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D.
Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for
their work on that specification, from which significant amounts of their work on that specification, from which significant amounts of
text were borrowed. See Section 6 of [RFC2617] for further text were borrowed. See Section 6 of [RFC2617] for further
acknowledgements. acknowledgements.
The internationalization problem with respect to the character The internationalization problem with respect to the character
encoding scheme used for user-pass has been reported as a Mozilla bug encoding scheme used for user-pass was reported as a Mozilla bug back
back in the year 2000 (see in the year 2000 (see
<https://bugzilla.mozilla.org/show_bug.cgi?id=41489> and also the <https://bugzilla.mozilla.org/show_bug.cgi?id=41489> and also the
more recent <https://bugzilla.mozilla.org/show_bug.cgi?id=656213>). 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. It was Andrew Clover's idea to address it using a new auth-param.
We also thank the members of the HTTPAuth Working Group and other We also thank the members of the HTTPAuth Working Group and other
reviewers, namely Stephen Farrell, Bjoern Hoehrmann, Kari Hurtta, reviewers, namely Stephen Farrell, Roy Fielding, Bjoern Hoehrmann,
Amos Jeffries, Benjamin Kaduk, Michael Koeller, Eric Lawrence, James Daniel Kahn Gillmor, Tony Hansen, Kari Hurtta, Amos Jeffries,
Manger, Alexey Melnikov, Kathleen Moriarty, Yaron Sheffer, Michael Benjamin Kaduk, Michael Koeller, Eric Lawrence, Barry Leiba, James
Sweet, and Martin Thomson for feedback on this revision. Manger, Alexey Melnikov, Kathleen Moriarty, Juergen Schoenwaelder,
Yaron Sheffer, Meral Shirazipour, Michael Sweet, and Martin Thomson
for feedback on this revision.
7. References 7. References
7.1. Normative References 7.1. Normative References
[PRECIS] Saint-Andre, P. and A. Melnikov, "Preparation, [PRECIS] Saint-Andre, P. and A. Melnikov, "Preparation,
Enforcement, and Comparison of Internationalized Enforcement, and Comparison of Internationalized
Strings Representing Usernames and Passwords", Strings Representing Usernames and Passwords",
draft-ietf-precis-saslprepbis-13 (work in progress), draft-ietf-precis-saslprepbis-13 (work in progress),
December 2014. December 2014.
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7.2. Informative References 7.2. Informative References
[AUTHINFO] Reschke, J., "The Hypertext Transfer Protocol (HTTP) [AUTHINFO] Reschke, J., "The Hypertext Transfer Protocol (HTTP)
Authentication-Info and Proxy-Authentication-Info Authentication-Info and Proxy-Authentication-Info
Response Header Fields", Response Header Fields",
draft-ietf-httpbis-auth-info-02 (work in progress), draft-ietf-httpbis-auth-info-02 (work in progress),
February 2015. February 2015.
[DIGEST] Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP [DIGEST] Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
Digest Access Authentication", Digest Access Authentication",
draft-ietf-httpauth-digest-13 (work in progress), draft-ietf-httpauth-digest-14 (work in progress),
February 2015. February 2015.
[ISO-8859-1] International Organization for Standardization, [ISO-8859-1] International Organization for Standardization,
"Information technology -- 8-bit single-byte coded "Information technology -- 8-bit single-byte coded
graphic character sets -- Part 1: Latin alphabet No. graphic character sets -- Part 1: Latin alphabet No.
1", ISO/IEC 8859-1:1998, 1998. 1", ISO/IEC 8859-1:1998, 1998.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence,
S., Leach, P., Luotonen, A., and L. Stewart, "HTTP S., Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication: Basic and Digest Access
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User agents not implementing 'charset' will continue to work as User agents not implementing 'charset' will continue to work as
before, ignoring the new parameter. before, ignoring the new parameter.
User agents which already default to the UTF-8 encoding implement User agents which already default to the UTF-8 encoding implement
'charset' by definition. 'charset' by definition.
Other user agents can keep their default behavior, and switch to Other user agents can keep their default behavior, and switch to
UTF-8 when seeing the new parameter. UTF-8 when seeing the new parameter.
B.2. Origin Servers B.2. Servers
Origin servers that do not support non-US-ASCII characters in Servers that do not support non-US-ASCII characters in credentials do
credentials do not require any changes to support 'charset'. not require any changes to support 'charset'.
Origin servers that need to support non-US-ASCII characters, but Servers that need to support non-US-ASCII characters, but cannot use
cannot use the UTF-8 character encoding scheme will not be affected; the UTF-8 character encoding scheme will not be affected; they will
they will continue to function as well or as badly as before. continue to function as well or as badly as before.
Finally, origin servers that need to support non-US-ASCII characters Finally, servers that need to support non-US-ASCII characters and can
and can use the UTF-8 character encoding scheme can opt in as use the UTF-8 character encoding scheme can opt in by specifying the
described above. In the worst case, they'll continue to see either charset parameter in the authentication challenge. Clients that do
broken credentials or no credentials at all (depending on how legacy understand the charset parameter will then start to use UTF-8, while
clients handle characters they cannot encode). other clients will continue to send credentials in their default
encoding, broken credentials, or no credentials at all. Until all
clients are upgraded to support UTF-8, servers are likely to see both
UTF-8 and "legacy" encodings in requests. When processing as UTF-8
fails (due to a failure to decode as UTF-8 or a mismatch of user-id/
password), a server might try a fallback to the previously supported
legacy encoding in order to accomodate these legacy clients. Note
that implicit retries need to be done carefully; for instance, some
subsystems might detect repeated login failures and treat them as
potential credentials guessing attack.
B.3. Why not simply switch the default encoding to UTF-8? B.3. Why not simply switch the default encoding to UTF-8?
There are sites in use today that default to a local character There are sites in use today that default to a local character
encoding scheme, such as ISO-8859-1 ([ISO-8859-1]), and expect user encoding scheme, such as ISO-8859-1 ([ISO-8859-1]), and expect user
agents to use that encoding. Authentication on these sites will stop agents to use that encoding. Authentication on these sites will stop
to work if the user agent switches to a different encoding, such as working if the user agent switches to a different encoding, such as
UTF-8. UTF-8.
Note that sites might even inspect the User-Agent header field Note that sites might even inspect the User-Agent header field
([RFC7231], Section 5.5.3) to decide what character encoding scheme ([RFC7231], Section 5.5.3) to decide which character encoding scheme
to expect from the client. Therefore they might support UTF-8 for to expect from the client. Therefore they might support UTF-8 for
some user agents, but default to something else for others. User some user agents, but default to something else for others. User
agents in the latter group will have to continue to do what they do agents in the latter group will have to continue to do what they do
today until the majority of these servers have been upgraded to today until the majority of these servers have been upgraded to
always use UTF-8. always use UTF-8.
Appendix C. Change Log (to be removed by RFC Editor before publication) Appendix C. Change Log (to be removed by RFC Editor before publication)
C.1. Since RFC 2617 C.1. Since RFC 2617
This draft acts as a baseline for tracking subsequent changes to the This draft acts as a baseline for tracking subsequent changes to the
specification. As such, it extracts the definition of "Basic", plus specification. As such, it extracts the definition of "Basic", plus
the related Security Considerations, and also adds the IANA the related Security Considerations, and also adds the IANA
registration of the scheme. Changes to the actual definition will be registration of the scheme. Changes to the actual definition will be
made in subsequent drafts. made in subsequent drafts.
C.2. Since draft-ietf-httpauth-basicauth-update-00 C.2. Since draft-ietf-httpauth-basicauth-update-00
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Updated DIGEST and PRECIS references. Updated DIGEST and PRECIS references.
Avoid the term "obfuscated". Say "free-form string" instead of Avoid the term "obfuscated". Say "free-form string" instead of
"opaque string" in realm description. "opaque string" in realm description.
Mention AUTHINFO as yet another draft that helps obsoleting RFC 2617. Mention AUTHINFO as yet another draft that helps obsoleting RFC 2617.
Add a note about the complexity of parsing challenges correctly. Add a note about the complexity of parsing challenges correctly.
C.8. Since draft-ietf-httpauth-basicauth-update-06
Clarify IANA action.
Remove leftover statement about use of ABNF (which was changed in
-02).
Security considerations: mention normalization and password storage.
Rewrite advice on counterfeiting attacks.
Update DIGEST reference.
Rewrite text about colons in user-id.
Expand deployment guidance.
Author's Address Author's Address
Julian F. Reschke Julian F. Reschke
greenbytes GmbH greenbytes GmbH
Hafenweg 16 Hafenweg 16
Muenster, NW 48155 Muenster, NW 48155
Germany Germany
EMail: julian.reschke@greenbytes.de EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/ URI: http://greenbytes.de/tech/webdav/
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