draft-ietf-sasl-saslprep-09.txt   draft-ietf-sasl-saslprep-10.txt 
INTERNET-DRAFT Kurt D. Zeilenga INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standards Track OpenLDAP Foundation Intended Category: Standards Track OpenLDAP Foundation
Expires: October 2004 28 April 2004 Expires: January 2005 18 July 2004
SASLprep: Stringprep profile for user names and passwords SASLprep: Stringprep profile for user names and passwords
<draft-ietf-sasl-saslprep-09.txt> <draft-ietf-sasl-saslprep-10.txt>
Status of Memo 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 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, 4 of RFC 3667. By submitting this Internet-Draft, I certify that any
and any of which I become aware will be disclosed, in accordance with applicable patent or other IPR claims of which I am aware have been
RFC 3668. disclosed, or will be 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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The use of simple user names and passwords in authentication and The use of simple user names and passwords in authentication and
authorization is pervasive on the Internet. To increase the authorization is pervasive on the Internet. To increase the
likelihood that user name and password input and comparison work in likelihood that user name and password input and comparison work in
ways that make sense for typical users throughout the world, this ways that make sense for typical users throughout the world, this
document defines rules for preparing internationalized user names and document defines rules for preparing internationalized user names and
passwords for comparison. For simplicity and implementation ease, a passwords for comparison. For simplicity and implementation ease, a
single algorithm is defined for both user names and passwords. single algorithm is defined for both user names and passwords.
The algorithm assumes all strings are comprised of characters from the The algorithm assumes all strings are comprised of characters from the
Unicode character set. Unicode [Unicode] character set.
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., email 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, or require different handling (e.g., case folding). data, or require different handling (e.g., case folding).
This document by itself does not alter the technical specification any This document by itself does not alter the technical specification any
existing protocols. Any specification that wishes to use the existing protocols. Any specification that wishes to use the
algorithm described in this document needs to explicitly incorporate algorithm described in this document needs to explicitly incorporate
this document and provide precise details as to where and how this this document and provide precise details as to where and how this
algorithm is used by implementations of that specification. algorithm is used by implementations of that specification.
2. The SASLprep profile 2. The SASLprep profile
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3. Examples 3. Examples
The following table provides examples of how various character data is The following table provides examples of how various character data is
transformed by SASLprep string preparation algorithm transformed by SASLprep string preparation algorithm
# Input Output Comments # Input Output Comments
- ----- ------ -------- - ----- ------ --------
1 I<U+00AD>X IX SOFT HYPHEN mapped to nothing 1 I<U+00AD>X IX SOFT HYPHEN mapped to nothing
2 user user no transformation 2 user user no transformation
3 USER USER case preserved, will not match #3 3 USER USER case preserved, will not match #2
4 <U+00AA> a output is NFKC, input in ISO 8859-1 4 <U+00AA> a output is NFKC, input in ISO 8859-1
5 <U+2168> IX output is NFKC, will match #1 5 <U+2168> IX output is NFKC, will match #1
6 <U+0007> Error - prohibited character 6 <U+0007> Error - prohibited character
7 <U+0627><U+0031> Error - bidirectional check 7 <U+0627><U+0031> Error - bidirectional check
4. Security Considerations 4. Security Considerations
This profile is intended to used to prepare simple user names and This profile is intended to be 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 was specifically
designed such that its output is canonical. designed such that its output is canonical, and it is well-formed.
However, due to an anomaly [PR29] in the specification of Unicode
normalization, canonical equivalence is not guaranteed for a select
few character sequences. These sequences, however, do not appear in
well-formed text. This specification was published despite this known
technical problem. It is expected that this specification will be
revised before further progression on the Standards Track (after
[Unicode] and/or [StringPrep] specifications have been updated to
address this problem).
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, domain names),
names). Nor is the profile intended to be used for simple user names nor is the profile intended to be used for simple user names which
which require different handling (such as case folding). Protocols require different handling (such as case folding). Protocols (or
(or applications of those protocols) which have application-specific applications of those protocols) which have application-specific
identity forms and/or comparison algorithms should use mechanisms identity forms and/or comparison algorithms should use mechanisms
specifically designed for 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
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[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.
[PR29] "Public Review Issue #29: Normalization Issue",
<http://www.unicode.org/review/pr-29.html>, February
2004.
9. Author'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
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Copies of IPR disclosures made to the IETF Secretariat and any Copies of IPR disclosures made to the IETF Secretariat and any
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attempt made to obtain a general license or permission for the use of attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this specification such proprietary rights by implementers or users of this specification
can be obtained from the IETF on-line IPR repository at can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
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Full Copyright Full Copyright
Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78 and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
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INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
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