7 INTERNET-DRAFT Kurt D. Zeilenga
8 Intended Category: Standards Track OpenLDAP Foundation
9 Expires: August 2004 15 February 2004
12 SASLprep: Stringprep profile for user names and passwords
13 <draft-ietf-sasl-saslprep-05.txt>
18 This document is an Internet-Draft and is in full conformance with all
19 provisions of Section 10 of RFC 2026.
21 This document is intended to be, after appropriate review and
22 revision, submitted to the RFC Editor as a Standards Track document.
23 Distribution of this memo is unlimited. Technical discussion of this
24 document will take place on the IETF SASL mailing list
25 <ietf-sasl@imc.org>. Please send editorial comments directly to the
26 document editor <Kurt@OpenLDAP.org>.
28 Internet-Drafts are working documents of the Internet Engineering Task
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31 Internet-Drafts are draft documents valid for a maximum of six months
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33 time. It is inappropriate to use Internet-Drafts as reference
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36 The list of current Internet-Drafts can be accessed at
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41 Copyright (C) The Internet Society (2004). All Rights Reserved.
43 Please see the Full Copyright section near the end of this document
49 This document describes how to prepare Unicode strings representing
50 user names and passwords for comparison. The document defines the
51 "SASLprep" profile of the "stringprep" algorithm to be used for both
52 user names and passwords. This profile is intended to be used by
53 Simple Authentication and Security Layer (SASL) mechanisms (such as
54 PLAIN, CRAM-MD5, and DIGEST-MD5) as well as other protocols exchanging
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63 user names and/or passwords.
68 The use of simple user names and passwords in authentication and
69 authorization is pervasive on the Internet. To increase the
70 likelihood that user name and password input and comparison work in
71 ways that make sense for typical users throughout the world, this
72 document defines rules for preparing internationalized user names and
73 passwords for comparison. For simplicity and implementation ease, a
74 single algorithm is defined for both user names and passwords.
76 This document defines the "SASLprep" profile of the "stringprep"
77 algorithm [StringPrep].
79 The profile is designed for use in Simple Authentication and Security
80 Layer ([SASL]) mechanisms such as [PLAIN]. It may be applicable
81 elsewhere simple user names and passwords are used. This profile is
82 not intended to be used to prepare identity strings which are not
83 simple user names (e.g., e-mail addresses, domain names, distinguished
84 names), or where identity or password strings which are not character
88 2. The SASLprep profile
90 This section defines the "SASLprep" profile. This profile is intended
91 to be used to prepare strings representing simple user names and
94 This profile uses Unicode 3.2, as defined in [StringPrep, A.1].
96 Character names in this document use the notation for code points and
97 names from the Unicode Standard [Unicode]. For example, the letter
98 "a" may be represented as either <U+0061> or <LATIN SMALL LETTER A>.
99 In the lists of mappings and the prohibited characters, the "U+" is
100 left off to make the lists easier to read. The comments for character
101 ranges are shown in square brackets (such as "[CONTROL CHARACTERS]")
102 and do not come from the standard.
104 Note: a glossary of terms used in Unicode can be found in [Glossary].
105 Information on the Unicode character encoding model can be found in
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119 This profile specifies:
120 - non-ASCII space characters [StringPrep, C.1.2] be mapped to SPACE
123 - the "commonly mapped to nothing" characters [StringPrep, B.1] be
130 This profile specifies using Unicode normalization form KC, as
131 described in Section 4 of [StringPrep].
134 2.3. Prohibited Output
136 This profile specifies the following characters:
138 - Non-ASCII space characters [StringPrep, C.1.2],
139 - ASCII control characters [StringPrep, C.2.1],
140 - Non-ASCII control characters [StringPrep, C.2.2],
141 - Private Use [StringPrep, C.3],
142 - Non-character code points [StringPrep, C.4],
143 - Surrogate code points [StringPrep, C.5],
144 - Inappropriate for plain text [StringPrep, C.6],
145 - Inappropriate for canonical representation [StringPrep, C.7],
146 - Change display properties or are deprecated [StringPrep, C.8], and
147 - Tagging characters [StringPrep, C.9].
149 are prohibited output.
152 2.4. Bidirectional characters
154 This profile specifies checking bidirectional strings as described in
155 [StringPrep, Section 6].
158 2.5. Unassigned Code Points
160 This profile specifies [StringPrep, A.1] table as its list of
161 unassigned code points.
164 3. Security Considerations
166 This profile is intended to used to prepare simple user names and
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175 passwords strings for comparison or use in cryptographic functions
176 (e.g., message digests).
178 It is not intended to be used for to prepare identity strings which
179 are not simple user names (e.g., distinguished names and domain
180 names). Nor is the profile intended to be used for simple user names
181 which require different handling. Protocols (or applications of those
182 protocols) which have application-specific identity forms and/or
183 comparison algorithms should use mechanisms specifically designed for
184 these forms and algorithms.
186 Application of string preparation may have an impact upon the
187 feasibility of brute force and dictionary attacks. While the number
188 of possible prepared strings is less than the number of possible
189 Unicode strings, the number of usable names and passwords is hoped to
192 User names and passwords should be protected from eavesdropping.
194 General "stringprep" and Unicode security considerations apply. Both
195 are discussed in [StringPrep].
198 4. IANA Considerations
200 This document details the "SASLprep" profile of [StringPrep] protocol.
201 Upon Standards Action the profile should be registered in the
202 stringprep profile registry.
204 Name of this profile: SASLprep
205 RFC in which the profile is defined: This RFC
206 Indicator whether or not this is the newest version of the
207 profile: This is the first version of the SASPprep profile.
212 This document borrows text from "Preparation of Internationalized
213 Strings ('stringprep')" and "Nameprep: A Stringprep Profile for
214 Internationalized Domain Names", both by Paul Hoffman and Marc
217 This document is a product of the IETF SASL WG.
220 6. Normative References
222 [StringPrep] Hoffman P. and M. Blanchet, "Preparation of
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228 INTERNET-DRAFT draft-ietf-sasl-saslprep-05.txt 15 February 2004
231 Internationalized Strings ('stringprep')",
232 draft-hoffman-rfc3454bis-xx.txt, a work in progress.
234 [SASL] Melnikov, A. (Editor), "Simple Authentication and
235 Security Layer (SASL)",
236 draft-ietf-sasl-rfc2222bis-xx.txt, a work in progress.
238 [Unicode] The Unicode Consortium, "The Unicode Standard, Version
239 3.2.0" is defined by "The Unicode Standard, Version 3.0"
240 (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5),
241 as amended by the "Unicode Standard Annex #27: Unicode
242 3.1" (http://www.unicode.org/reports/tr27/) and by the
243 "Unicode Standard Annex #28: Unicode 3.2"
244 (http://www.unicode.org/reports/tr28/).
247 7. Informative References
249 [Glossary] The Unicode Consortium, "Unicode Glossary",
250 <http://www.unicode.org/glossary/>.
252 [CharModel] Whistler, K. and M. Davis, "Unicode Technical Report
253 #17, Character Encoding Model", UTR17,
254 <http://www.unicode.org/unicode/reports/tr17/>, August
257 [CRAM-MD5] Nerenberg, L., "The CRAM-MD5 SASL Mechanism",
258 draft-ietf-sasl-crammd5-xx.txt, a work in progress.
260 [DIGEST-MD5] Leach, P., C. Newman, and A. Melnikov, "Using Digest
261 Authentication as a SASL Mechanism",
262 draft-ietf-sasl-rfc2831bis-xx.txt, a work in progress.
264 [PLAIN] Zeilenga, K. (Editor), "The Plain SASL Mechanism",
265 draft-ietf-sasl-plain-xx.txt, a work in progress.
273 Email: Kurt@OpenLDAP.org
277 Intellectual Property Rights
282 Zeilenga SASLprep [Page 5]
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310 Copyright (C) The Internet Society (2004). All Rights Reserved.
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