draft-ietf-sasl-saslprep-08.txt   draft-ietf-sasl-saslprep-09.txt 
INTERNET-DRAFT Kurt D. Zeilenga INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standards Track OpenLDAP Foundation Intended Category: Standards Track OpenLDAP Foundation
Expires: September 2004 12 April 2004 Expires: October 2004 28 April 2004
SASLprep: Stringprep profile for user names and passwords SASLprep: Stringprep profile for user names and passwords
<draft-ietf-sasl-saslprep-08.txt> <draft-ietf-sasl-saslprep-09.txt>
Status of Memo Status of Memo
This document is an Internet-Draft and is in full conformance with all This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC 2026. provisions of Section 10 of RFC 2026.
This document is intended to be, after appropriate review and This document is intended to be, after appropriate review and
revision, submitted to the RFC Editor as a Standards Track document. revision, submitted to the RFC Editor as a Standards Track document.
Distribution of this memo is unlimited. Technical discussion of this Distribution of this memo is unlimited. Technical discussion of this
document will take place on the IETF SASL mailing list document will take place on the IETF SASL mailing list
<ietf-sasl@imc.org>. Please send editorial comments directly to the <ietf-sasl@imc.org>. Please send editorial comments directly to the
document editor <Kurt@OpenLDAP.org>. document editor <Kurt@OpenLDAP.org>.
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patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance with
RFC 3668.
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Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
Please see the Full Copyright section near the end of this document Please see the Full Copyright section near the end of this document
for more information. for more information.
Abstract Abstract
This document describes how to prepare Unicode strings representing This document describes how to prepare Unicode strings representing
user names and passwords for comparison. The document defines the user names and passwords for comparison. The document defines the
"SASLprep" profile of the "stringprep" algorithm to be used for both "SASLprep" profile of the "stringprep" algorithm to be used for both
user names and passwords. This profile is intended to be used by user names and passwords. This profile is intended to be used by
Simple Authentication and Security Layer (SASL) mechanisms (such as Simple Authentication and Security Layer (SASL) mechanisms (such as
PLAIN, CRAM-MD5, and DIGEST-MD5) as well as other protocols exchanging PLAIN, CRAM-MD5, and DIGEST-MD5) as well as other protocols exchanging
simple user names and/or passwords. simple user names and/or passwords.
1. Introduction 1. Introduction
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This document defines the "SASLprep" profile of the "stringprep" This document defines the "SASLprep" profile of the "stringprep"
algorithm [StringPrep]. algorithm [StringPrep].
The profile is designed for use in Simple Authentication and Security The profile is designed for use in Simple Authentication and Security
Layer ([SASL]) mechanisms such as [PLAIN]. It may be applicable Layer ([SASL]) mechanisms such as [PLAIN]. It may be applicable
elsewhere simple user names and passwords are used. This profile is elsewhere simple user names and passwords are used. This profile is
not intended to be used to prepare identity strings which are not not intended to be used to prepare identity strings which are not
simple user names (e.g., e-mail addresses, domain names, distinguished simple user names (e.g., e-mail addresses, domain names, distinguished
names), or where identity or password strings which are not character names), or where identity or password strings which are not character
data. data, or require different handling (e.g., case folding).
This document by itself does not alter the technical specification any
existing protocols. Any specification that wishes to use the
algorithm described in this document needs to explicitly incorporate
this document and provide precise details as to where and how this
algorithm is used by implementations of that specification.
2. The SASLprep profile 2. The SASLprep profile
This section defines the "SASLprep" profile of the "stringprep" This section defines the "SASLprep" profile of the "stringprep"
algorithm [StringPrep]. This profile is intended to be used to algorithm [StringPrep]. This profile is intended to be used to
prepare strings representing simple user names and passwords. prepare strings representing simple user names and passwords.
This profile uses Unicode 3.2 [Unicode]. This profile uses Unicode 3.2 [Unicode].
Character names in this document use the notation for code points and Character names in this document use the notation for code points and
skipping to change at page 3, line 46 skipping to change at page 4, line 15
2.4. Bidirectional characters 2.4. Bidirectional characters
This profile specifies checking bidirectional strings as described in This profile specifies checking bidirectional strings as described in
[StringPrep, Section 6]. [StringPrep, Section 6].
2.5. Unassigned Code Points 2.5. Unassigned Code Points
This profile specifies [StringPrep, A.1] table as its list of This profile specifies [StringPrep, A.1] table as its list of
unassigned code points. unassigned code points.
3. Security Considerations 3. Examples
The following table provides examples of how various character data is
transformed by SASLprep string preparation algorithm
# Input Output Comments
- ----- ------ --------
1 I<U+00AD>X IX SOFT HYPHEN mapped to nothing
2 user user no transformation
3 USER USER case preserved, will not match #3
4 <U+00AA> a output is NFKC, input in ISO 8859-1
5 <U+2168> IX output is NFKC, will match #1
6 <U+0007> Error - prohibited character
7 <U+0627><U+0031> Error - bidirectional check
4. Security Considerations
This profile is intended to used to prepare simple user names and This profile is intended to used to prepare simple user names and
passwords strings for comparison or use in cryptographic functions passwords strings for comparison or use in cryptographic functions
(e.g., message digests). The preparation algorithm is specifically (e.g., message digests). The preparation algorithm is specifically
designed such that its output is canonical. designed such that its output is canonical.
It is not intended to be used for to prepare identity strings which It is not intended to be used for to prepare identity strings which
are not simple user names (e.g., distinguished names and domain are not simple user names (e.g., distinguished names and domain
names). Nor is the profile intended to be used for simple user names names). Nor is the profile intended to be used for simple user names
which require different handling. Protocols (or applications of those which require different handling (such as case folding). Protocols
protocols) which have application-specific identity forms and/or (or applications of those protocols) which have application-specific
comparison algorithms should use mechanisms specifically designed for identity forms and/or comparison algorithms should use mechanisms
these forms and algorithms. specifically designed for these forms and algorithms.
Application of string preparation may have an impact upon the Application of string preparation may have an impact upon the
feasibility of brute force and dictionary attacks. While the number feasibility of brute force and dictionary attacks. While the number
of possible prepared strings is less than the number of possible of possible prepared strings is less than the number of possible
Unicode strings, the number of usable names and passwords is greater Unicode strings, the number of usable names and passwords is greater
than if only ASCII was used. Though SASLprep eliminates some of than if only ASCII was used. Though SASLprep eliminates some of
Unicode code point sequences as possible prepared strings, that Unicode code point sequences as possible prepared strings, that
elimination generally makes the (canonical) output forms practicable elimination generally makes the (canonical) output forms practicable
and prohibits nonsensical inputs. and prohibits nonsensical inputs.
User names and passwords should be protected from eavesdropping. User names and passwords should be protected from eavesdropping.
General "stringprep" and Unicode security considerations apply. Both General "stringprep" and Unicode security considerations apply. Both
are discussed in [StringPrep]. are discussed in [StringPrep].
4. IANA Considerations 5. IANA Considerations
This document details the "SASLprep" profile of [StringPrep] protocol. This document details the "SASLprep" profile of [StringPrep] protocol.
Upon Standards Action the profile should be registered in the Upon Standards Action the profile should be registered in the
stringprep profile registry. stringprep profile registry.
Name of this profile: SASLprep Name of this profile: SASLprep
RFC in which the profile is defined: This RFC RFC in which the profile is defined: This RFC
Indicator whether or not this is the newest version of the Indicator whether or not this is the newest version of the
profile: This is the first version of the SASPprep profile. profile: This is the first version of the SASPprep profile.
5. Acknowledgment 6. Acknowledgment
This document borrows text from "Preparation of Internationalized This document borrows text from "Preparation of Internationalized
Strings ('stringprep')" and "Nameprep: A Stringprep Profile for Strings ('stringprep')" and "Nameprep: A Stringprep Profile for
Internationalized Domain Names", both by Paul Hoffman and Marc Internationalized Domain Names", both by Paul Hoffman and Marc
Blanchet. Blanchet.
This document is a product of the IETF SASL WG. This document is a product of the IETF SASL WG.
6. Normative References 7. Normative References
[StringPrep] Hoffman, P. and M. Blanchet, "Preparation of [StringPrep] Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ('stringprep')", RFC 3454, Internationalized Strings ('stringprep')", RFC 3454,
December 2002. December 2002.
[Unicode] The Unicode Consortium, "The Unicode Standard, Version [Unicode] The Unicode Consortium, "The Unicode Standard, Version
3.2.0" is defined by "The Unicode Standard, Version 3.0" 3.2.0" is defined by "The Unicode Standard, Version 3.0"
(Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5), (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5),
as amended by the "Unicode Standard Annex #27: Unicode as amended by the "Unicode Standard Annex #27: Unicode
3.1" (http://www.unicode.org/reports/tr27/) and by the 3.1" (http://www.unicode.org/reports/tr27/) and by the
"Unicode Standard Annex #28: Unicode 3.2" "Unicode Standard Annex #28: Unicode 3.2"
(http://www.unicode.org/reports/tr28/). (http://www.unicode.org/reports/tr28/).
7. Informative References 8. Informative References
[Glossary] The Unicode Consortium, "Unicode Glossary", [Glossary] The Unicode Consortium, "Unicode Glossary",
<http://www.unicode.org/glossary/>. <http://www.unicode.org/glossary/>.
[CharModel] Whistler, K. and M. Davis, "Unicode Technical Report [CharModel] Whistler, K. and M. Davis, "Unicode Technical Report
#17, Character Encoding Model", UTR17, #17, Character Encoding Model", UTR17,
<http://www.unicode.org/unicode/reports/tr17/>, August <http://www.unicode.org/unicode/reports/tr17/>, August
2000. 2000.
[SASL] Melnikov, A. (Editor), "Simple Authentication and [SASL] Melnikov, A. (Editor), "Simple Authentication and
Security Layer (SASL)", Security Layer (SASL)",
skipping to change at page 5, line 43 skipping to change at page 6, line 26
[CRAM-MD5] Nerenberg, L., "The CRAM-MD5 SASL Mechanism", [CRAM-MD5] Nerenberg, L., "The CRAM-MD5 SASL Mechanism",
draft-ietf-sasl-crammd5-xx.txt, a work in progress. draft-ietf-sasl-crammd5-xx.txt, a work in progress.
[DIGEST-MD5] Leach, P., C. Newman, and A. Melnikov, "Using Digest [DIGEST-MD5] Leach, P., C. Newman, and A. Melnikov, "Using Digest
Authentication as a SASL Mechanism", Authentication as a SASL Mechanism",
draft-ietf-sasl-rfc2831bis-xx.txt, a work in progress. draft-ietf-sasl-rfc2831bis-xx.txt, a work in progress.
[PLAIN] Zeilenga, K. (Editor), "The Plain SASL Mechanism", [PLAIN] Zeilenga, K. (Editor), "The Plain SASL Mechanism",
draft-ietf-sasl-plain-xx.txt, a work in progress. draft-ietf-sasl-plain-xx.txt, a work in progress.
8. Editor's Address 9. Author's Address
Kurt D. Zeilenga Kurt D. Zeilenga
OpenLDAP Foundation OpenLDAP Foundation
Email: Kurt@OpenLDAP.org Email: Kurt@OpenLDAP.org
Intellectual Property Rights Intellectual Property Rights
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
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