INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standards Track OpenLDAP Foundation
Expires in six months 27 October 2003
SASLprep: Stringprep profile for user names and passwords
<draft-ietf-sasl-saslprep-04.txt>
Status of Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC 2026.
This document is intended to be, after appropriate review and
revision, submitted to the RFC Editor as a Standards Track document.
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Copyright (C) The Internet Society (2003). All Rights Reserved.
Please see the Full Copyright section near the end of this document
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Abstract
This document describes how to prepare Unicode strings representing
user names and passwords for comparison. The document defines the
"SASLprep" profile of the "stringprep" algorithm to be used for both
user names and passwords. This profile is intended to be used by
Simple Authentication and Security Layer (SASL) mechanisms (such as
PLAIN, CRAM-MD5, and DIGEST-MD5) as well as other protocols exchanging
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user names and/or passwords.
1. Introduction
The use of simple user names and passwords in authentication and
authorization is pervasive on the Internet. To increase the
likelihood that user name and password input and comparison work in
ways that make sense for typical users throughout the world, this
document defines rules for preparing internationalized user names and
passwords for comparison. For simplicity and implementation ease, a
single algorithm is defined for both user names and passwords.
This document defines the "SASLprep" profile of the "stringprep"
algorithm [StringPrep].
The profile is designed for use in Simple Authentication and Security
Layer ([SASL]) mechanisms such as [PLAIN]. It may be applicable
elsewhere simple user names and passwords are used. This profile is
not intended to be used for arbitrary text. This profile is also not
intended to be used to prepare identity strings which are not simple
user names (e.g., e-mail addresses, domain names, distinguished
names).
2. The SASLprep profile
This section defines the "SASLprep" profile. This profile is intended
to be used to prepare strings representing simple user names and
passwords.
This profile uses Unicode 3.2, as defined in [StringPrep, A.1].
Character names in this document use the notation for code points and
names from the Unicode Standard [Unicode]. For example, the letter
"a" may be represented as either <U+0061> or <LATIN SMALL LETTER A>.
In the lists of mappings and the prohibited characters, the "U+" is
left off to make the lists easier to read. The comments for character
ranges are shown in square brackets (such as "[CONTROL CHARACTERS]")
and do not come from the standard.
Note: a glossary of terms used in Unicode can be found in [Glossary].
Information on the Unicode character encoding model can be found in
[CharModel].
2.1. Mapping
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This profile specifies:
- non-ASCII space characters [StringPrep, C.1.2] be mapped to SPACE
(U+0020), and
- the "commonly mapped to nothing" characters [StringPrep, B.1] be
mapped to nothing.
2.2. Normalization
This profile specifies using Unicode normalization form KC, as
described in Section 4 of [StringPrep].
2.3. Prohibited Output
This profile specifies the following characters:
- Non-ASCII space characters [StringPrep, C.1.2],
- ASCII control characters [StringPrep, C.2.1],
- Non-ASCII control characters [StringPrep, C.2.2],
- Private Use [StringPrep, C.3],
- Non-character code points [StringPrep, C.4],
- Surrogate code points [StringPrep, C.5],
- Inappropriate for plain text [StringPrep, C.6],
- Inappropriate for canonical representation [StringPrep, C.7],
- Change display properties or are deprecated [StringPrep, C.8], and
- Tagging characters [StringPrep, C.9].
are prohibited output.
2.4. Bidirectional characters
This profile specifies checking bidirectional strings as described in
[StringPrep, Section 6].
2.5. Unassigned Code Points
This profile specifies [StringPrep, A.1] table as its list of
unassigned code points.
3. Security Considerations
This profile is intended to used to prepare simple user names and
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passwords for comparison. It is not intended to be used for to
prepare identities which are not simple user names (e.g.,
distinguished names and domain names). Nor is the profile intended to
be used for simple user names which require different handling.
Protocols (or applications of those protocols) which have
application-specific identity forms and/or comparison algorithms
should use mechanisms specifically designed for these forms and
algorithms.
User names and passwords should be protected from eavesdropping.
General "stringprep" and Unicode security considerations apply. Both
are discussed in [StringPrep].
4. IANA Considerations
This document details the "SASLprep" profile of [StringPrep] protocol.
Upon Standards Action the profile should be registered in the
stringprep profile registry.
Name of this profile: SASLprep
RFC in which the profile is defined: This RFC
Indicator whether or not this is the newest version of the
profile: This is the first version of the SASPprep profile.
5. Acknowledgment
This document borrows text from "Preparation of Internationalized
Strings ('stringprep')" and "Nameprep: A Stringprep Profile for
Internationalized Domain Names", both by Paul Hoffman and Marc
Blanchet.
This document is a product of the IETF SASL WG.
6. Normative References
[StringPrep] Hoffman P. and M. Blanchet, "Preparation of
Internationalized Strings ('stringprep')",
draft-hoffman-rfc3454bis-xx.txt, a work in progress.
[SASL] Melnikov, A. (Editor), "Simple Authentication and
Security Layer (SASL)",
draft-ietf-sasl-rfc2222bis-xx.txt, a work in progress.
[Unicode] The Unicode Consortium, "The Unicode Standard, Version
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3.2.0" is defined by "The Unicode Standard, Version 3.0"
(Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5),
as amended by the "Unicode Standard Annex #27: Unicode
3.1" (http://www.unicode.org/reports/tr27/) and by the
"Unicode Standard Annex #28: Unicode 3.2"
(http://www.unicode.org/reports/tr28/).
7. Informative References
[Glossary] The Unicode Consortium, "Unicode Glossary",
<http://www.unicode.org/glossary/>.
[CharModel] Whistler, K. and M. Davis, "Unicode Technical Report
#17, Character Encoding Model", UTR17,
<http://www.unicode.org/unicode/reports/tr17/>, August
2000.
[CRAM-MD5] Nerenberg, L., "The CRAM-MD5 SASL Mechanism",
draft-ietf-sasl-crammd5-xx.txt, a work in progress.
[DIGEST-MD5] Leach, P., C. Newman, and A. Melnikov, "Using Digest
Authentication as a SASL Mechanism",
draft-ietf-sasl-rfc2831bis-xx.txt, a work in progress.
[PLAIN] Zeilenga, K. (Editor), "The Plain SASL Mechanism",
draft-ietf-sasl-plain-xx.txt, a work in progress.
8. Editor's Address
Kurt Zeilenga
OpenLDAP Foundation
Email: kurt@OpenLDAP.org
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Full Copyright
Copyright (C) The Internet Society (2003). All Rights Reserved.
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