< draft-ietf-precis-saslprepbis-09.txt   draft-ietf-precis-saslprepbis-10.txt >
PRECIS P. Saint-Andre PRECIS P. Saint-Andre
Internet-Draft &yet Internet-Draft &yet
Obsoletes: 4013 (if approved) A. Melnikov Obsoletes: 4013 (if approved) A. Melnikov
Intended status: Standards Track Isode Ltd Intended status: Standards Track Isode Ltd
Expires: April 26, 2015 October 23, 2014 Expires: May 25, 2015 November 21, 2014
Preparation, Enforcement, and Comparison of Internationalized Strings Preparation, Enforcement, and Comparison of Internationalized Strings
Representing Usernames and Passwords Representing Usernames and Passwords
draft-ietf-precis-saslprepbis-09 draft-ietf-precis-saslprepbis-10
Abstract Abstract
This document describes methods for handling Unicode strings This document describes methods for handling Unicode strings
representing usernames and passwords. This document obsoletes RFC representing usernames and passwords. This document obsoletes RFC
4013. 4013.
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
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 26, 2015. This Internet-Draft will expire on May 25, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Usernames . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Usernames . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Definition . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Definition . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Preparation . . . . . . . . . . . . . . . . . . . . . . . 5 3.2. UsernameIdentifierClass Profile . . . . . . . . . . . . . 5
3.3. Enforcement . . . . . . . . . . . . . . . . . . . . . . . 5 3.2.1. Preparation . . . . . . . . . . . . . . . . . . . . . 5
3.4. Comparison . . . . . . . . . . . . . . . . . . . . . . . 6 3.2.2. Enforcement . . . . . . . . . . . . . . . . . . . . . 5
3.5. Case Mapping . . . . . . . . . . . . . . . . . . . . . . 6 3.2.3. Comparison . . . . . . . . . . . . . . . . . . . . . 6
3.6. Application-Layer Constructs . . . . . . . . . . . . . . 7 3.3. Case Mapping . . . . . . . . . . . . . . . . . . . . . . 6
3.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . 7 3.4. Application-Layer Constructs . . . . . . . . . . . . . . 7
3.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4. Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1. Definition . . . . . . . . . . . . . . . . . . . . . . . 9 4.1. Definition . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. Preparation . . . . . . . . . . . . . . . . . . . . . . . 10 4.2. PasswordFreeformClass Profile . . . . . . . . . . . . . . 10
4.3. Enforcement . . . . . . . . . . . . . . . . . . . . . . . 10 4.2.1. Preparation . . . . . . . . . . . . . . . . . . . . . 10
4.4. Comparison . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.2. Enforcement . . . . . . . . . . . . . . . . . . . . . 10
4.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.3. Comparison . . . . . . . . . . . . . . . . . . . . . 11
4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 11
5. Migration . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5. Migration . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. Usernames . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1. Usernames . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2. Passwords . . . . . . . . . . . . . . . . . . . . . . . . 13 5.2. Passwords . . . . . . . . . . . . . . . . . . . . . . . . 13
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6.1. UsernameIdentifierClass . . . . . . . . . . . . . . . . . 14 6.1. UsernameIdentifierClass Profile . . . . . . . . . . . . . 14
6.2. PasswordFreeformClass . . . . . . . . . . . . . . . . . . 15 6.2. PasswordFreeformClass Profile . . . . . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7.1. Password/Passphrase Strength . . . . . . . . . . . . . . 15 7.1. Password/Passphrase Strength . . . . . . . . . . . . . . 15
7.2. Identifier Comparison . . . . . . . . . . . . . . . . . . 15 7.2. Identifier Comparison . . . . . . . . . . . . . . . . . . 16
7.3. Reuse of PRECIS . . . . . . . . . . . . . . . . . . . . . 16 7.3. Reuse of PRECIS . . . . . . . . . . . . . . . . . . . . . 16
7.4. Reuse of Unicode . . . . . . . . . . . . . . . . . . . . 16 7.4. Reuse of Unicode . . . . . . . . . . . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1. Normative References . . . . . . . . . . . . . . . . . . 16 8.1. Normative References . . . . . . . . . . . . . . . . . . 16
8.2. Informative References . . . . . . . . . . . . . . . . . 16 8.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Differences from RFC 4013 . . . . . . . . . . . . . 18 Appendix A. Differences from RFC 4013 . . . . . . . . . . . . . 18
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 18 Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
Usernames and passwords are widely used for authentication and Usernames and passwords are widely used for authentication and
authorization on the Internet, either directly when provided in authorization on the Internet, either directly when provided in
plaintext (as in the SASL PLAIN mechanism [RFC4616] or the HTTP Basic plaintext (as in the SASL PLAIN mechanism [RFC4616] or the HTTP Basic
scheme [RFC2617]) or indirectly when provided as the input to a scheme [RFC2617] / [I-D.ietf-httpauth-basicauth-update]) or
cryptographic algorithm such as a hash function (as in the SASL SCRAM indirectly when provided as the input to a cryptographic algorithm
mechanism [RFC5802] or the HTTP Digest scheme [RFC2617]). such as a hash function (as in the SASL SCRAM mechanism [RFC5802] or
the HTTP Digest scheme [RFC2617] / [I-D.ietf-httpauth-digest]).
To increase the likelihood that the input and comparison of usernames To increase the likelihood that the input and comparison of usernames
and passwords will work in ways that make sense for typical users and passwords will work in ways that make sense for typical users
throughout the world, this document defines rules for preparing and throughout the world, this document defines rules for preparing,
comparing internationalized strings that represent usernames and enforcing, and comparing internationalized strings that represent
passwords. Such strings consist of characters from the Unicode usernames and passwords. Such strings consist of characters from the
character set [UNICODE], especially characters outside the ASCII Unicode character set [UNICODE], with special attention to characters
range [RFC20]. The rules for handling such strings are specified outside the ASCII range [RFC20]. The rules for handling such strings
through profiles of the string classes defined in the PRECIS are specified through profiles of the string classes defined in the
framework specification [I-D.ietf-precis-framework]. PRECIS framework specification [I-D.ietf-precis-framework].
Profiles of the PRECIS framework enable software to handle Unicode Profiles of the PRECIS framework enable software to handle Unicode
characters outside the ASCII range in an automated way, so that such characters outside the ASCII range in an automated way, so that such
characters are treated carefully and consistently in application characters are treated carefully and consistently in application
protocols. In large measure, these profiles are designed to protect protocols. In large measure, these profiles are designed to protect
application developers from the potentially negative consequences of application developers from the potentially negative consequences of
supporting the full range of Unicode characters. For instance, in supporting the full range of Unicode characters. For instance, in
almost all application protocols it would be dangerous to treat the almost all application protocols it would be dangerous to treat the
Unicode character SUPERSCRIPT ONE (U+0089) as equivalent to DIGIT ONE Unicode character SUPERSCRIPT ONE (U+0089) as equivalent to DIGIT ONE
(U+0031), since that would result in false positives during (U+0031), since that would result in false positives during
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The methods defined here might be applicable wherever usernames or The methods defined here might be applicable wherever usernames or
passwords are used. However, the methods are not intended for use in passwords are used. However, the methods are not intended for use in
preparing strings that are not usernames (e.g., email addresses and preparing strings that are not usernames (e.g., email addresses and
LDAP distinguished names), nor in cases where identifiers or secrets LDAP distinguished names), nor in cases where identifiers or secrets
are not strings (e.g., keys and certificates) or require specialized are not strings (e.g., keys and certificates) or require specialized
handling. handling.
This document obsoletes RFC 4013 (the "SASLprep" profile of This document obsoletes RFC 4013 (the "SASLprep" profile of
stringprep [RFC3454]) but can be used by technologies other than the stringprep [RFC3454]) but can be used by technologies other than the
Simple Authentication and Security Layer (SASL) [RFC4422], such as Simple Authentication and Security Layer (SASL) [RFC4422], such as
HTTP authentication [RFC2617]. HTTP authentication [RFC2617] / [I-D.ietf-httpauth-basicauth-update]
/ [I-D.ietf-httpauth-digest].
2. Terminology 2. Terminology
Many important terms used in this document are defined in Many important terms used in this document are defined in
[I-D.ietf-precis-framework], [RFC5890], [RFC6365], and [UNICODE]. [I-D.ietf-precis-framework], [RFC5890], [RFC6365], and [UNICODE].
The term "non-ASCII space" refers to any Unicode code point having a The term "non-ASCII space" refers to any Unicode code point having a
general category of "Zs", with the exception of U+0020 (here called general category of "Zs", with the exception of U+0020 (here called
"ASCII space"). "ASCII space").
As used here, the term "password" is not literally limited to a word; As used here, the term "password" is not literally limited to a word;
i.e., a password could be a passphrase consisting of more than one i.e., a password could be a passphrase consisting of more than one
word, perhaps separated by spaces or other such characters. word, perhaps separated by spaces or other such characters.
Some SASL mechanisms (e.g., CRAM-MD5, DIGEST-MD5, and SCRAM) specify Some SASL mechanisms (e.g., CRAM-MD5, DIGEST-MD5, and SCRAM) specify
that the authentication identity used in the context of such that the authentication identity used in the context of such
mechanisms is a "simple user name" (see Section 2 of [RFC4422] as mechanisms is a "simple user name" (see Section 2 of [RFC4422] as
well as [RFC4013]). Various application technologies also assume well as [RFC4013]). Various application technologies also assume
that the identity of a user or account takes the form of a username that the identity of a user or account takes the form of a username
(e.g., authentication for the HyperText Transfer Protocol [RFC2617]), (e.g., authentication for the HyperText Transfer Protocol [RFC2617] /
[I-D.ietf-httpauth-basicauth-update] / [I-D.ietf-httpauth-digest]),
whether or not they use SASL. Note well that the exact form of a whether or not they use SASL. Note well that the exact form of a
username in any particular SASL mechanism or application technology username in any particular SASL mechanism or application technology
is a matter for implementation and deployment, and that a username is a matter for implementation and deployment, and that a username
does not necessarily map to any particular application identifier does not necessarily map to any particular application identifier
(such as the localpart of an email address). (such as the localpart of an email address).
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
3. Usernames 3. Usernames
Detailed rules for the preparation, enforcement, and comparision of
usernames are provided in the following sections (on the distinction
between these actions, refer to [I-D.ietf-precis-framework]).
3.1. Definition 3.1. Definition
This document specifies that a username is a string of Unicode code This document specifies that a username is a string of Unicode code
points [UNICODE], encoded using UTF-8 [RFC3629], and structured points [UNICODE], encoded using UTF-8 [RFC3629], and structured as an
either as an ordered sequence of "userparts" (where the complete ordered sequence of "userparts" (where the complete username can
username can consist of a single userpart or a space-separated consist of a single userpart or a space-separated sequence of
sequence of userparts) or as a userpart@domainpart (where the userparts).
domainpart is an IP literal, an IPv4 address, or a fully-qualified
domain name).
The syntax for a username is defined as follows using the Augmented The syntax for a username is defined as follows using the Augmented
Backus-Naur Form (ABNF) [RFC5234]. Backus-Naur Form (ABNF) [RFC5234].
username = userpart [1*(1*SP userpart)] username = userpart *(1*SP userpart)
userpart = 1*(idbyte) userpart = 1*(idbyte)
; ;
; an "idbyte" is a byte used to represent a ; an "idbyte" is a byte used to represent a
; UTF-8 encoded Unicode code point that can be ; UTF-8 encoded Unicode code point that can be
; contained in a string that conforms to the ; contained in a string that conforms to the
; PRECIS "IdentifierClass" ; PRECIS "IdentifierClass"
; ;
All code points and blocks not explicitly allowed in the PRECIS All code points and blocks not explicitly allowed in the PRECIS
IdentifierClass are disallowed; this includes private use characters, IdentifierClass are disallowed; this includes private use characters,
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existing SASL mechanisms and SASL-using application protocols, and existing SASL mechanisms and SASL-using application protocols, and
even in most application protocols that do not currently use SASL. even in most application protocols that do not currently use SASL.
A username MUST NOT be zero bytes in length. This rule is to be A username MUST NOT be zero bytes in length. This rule is to be
enforced after any normalization and mapping of code points. enforced after any normalization and mapping of code points.
In protocols that provide usernames as input to a cryptographic In protocols that provide usernames as input to a cryptographic
algorithm such as a hash function, the client will need to perform algorithm such as a hash function, the client will need to perform
proper preparation of the username before applying the algorithm. proper preparation of the username before applying the algorithm.
3.2. Preparation 3.2. UsernameIdentifierClass Profile
The definition of the UsernameIdentifierClass profile is provided in
the following sections, including detailed information about
preparation, enforcement, and comparison (on the distinction between
these actions, refer to [I-D.ietf-precis-framework]).
3.2.1. Preparation
An entity that prepares a string for inclusion in a username slot An entity that prepares a string for inclusion in a username slot
MUST ensure that the string consists only of Unicode code points that MUST ensure that the string consists only of Unicode code points that
conform to the "IdentifierClass" base string class defined in conform to the "IdentifierClass" base string class defined in
[I-D.ietf-precis-framework]. In addition, the string MUST be encoded [I-D.ietf-precis-framework]. In addition, the string MUST be encoded
as UTF-8 [RFC3629]. as UTF-8 [RFC3629].
3.3. Enforcement 3.2.2. Enforcement
An entity that performs enforcement in username slots MUST prepare a An entity that performs enforcement in username slots MUST prepare a
string as described in the previous section and MUST also apply the string as described in the previous section and MUST also apply the
rules specified below for the UsernameIdentifierClass profile (these rules specified below for the UsernameIdentifierClass profile (these
rules MUST be applied in the order shown). rules MUST be applied in the order shown).
1. Width Mapping Rule: Fullwidth and halfwidth characters MUST be 1. Width Mapping Rule: Fullwidth and halfwidth characters MUST be
mapped to their decomposition mappings. mapped to their decomposition mappings.
2. Additional Mapping Rule: There is no additional mapping rule. 2. Additional Mapping Rule: There is no additional mapping rule.
3. Case Mapping Rule: There is no case mapping rule (although see 3. Case Mapping Rule: There is no case mapping rule (although see
Section 3.5 below). Section 3.3 below).
4. Normalization Rule: Unicode Normalization Form C (NFC) MUST be 4. Normalization Rule: Unicode Normalization Form C (NFC) MUST be
applied to all characters. applied to all characters.
5. Exclusion Rule: There is no exclusion rule. 5. Directionality Rule: Applications MUST apply the "Bidi Rule"
6. Directionaity Rule: Applications MUST apply the "Bidi Rule"
defined in [RFC5893] (i.e., each of the six conditions of the defined in [RFC5893] (i.e., each of the six conditions of the
Bidi Rule must be satisfied). Bidi Rule must be satisfied).
3.4. Comparison 3.2.3. Comparison
An entity that performs comparison of two strings before or after An entity that performs comparison of two strings before or after
their inclusion in username slots MUST prepare each string and their inclusion in username slots MUST prepare each string and
enforce the rules specified in the previous two sections. The two enforce the rules specified in the previous two sections. The two
strings are to be considered equivalent if they are an exact octet- strings are to be considered equivalent if they are an exact octet-
for-octet match (sometimes called "bit-string identity"). for-octet match (sometimes called "bit-string identity").
3.5. Case Mapping 3.3. Case Mapping
Case mapping is a matter for the application protocol, protocol Case mapping is a matter for the application protocol, protocol
implementation, or end deployment. In general, this document implementation, or end deployment. In general, this document
suggests that it is preferable to perform case mapping, since not suggests that it is preferable to perform case mapping, since not
doing so can lead to false positives during authentication and doing so can lead to false positives during authentication and
authorization (as described in [RFC6943]) and can result in confusion authorization (as described in [RFC6943]) and can result in confusion
among end users given the prevalence of case mapping in many existing among end users given the prevalence of case mapping in many existing
protocols and applications. However, there can be good reasons to protocols and applications. However, there can be good reasons to
not perform case mapping, such as backward compatibility with not perform case mapping, such as backward compatibility with
deployed infrastructure. deployed infrastructure.
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whether case mapping is to be applied to authorization whether case mapping is to be applied to authorization
identifiers. Such "SASL application protocols" SHOULD delay any identifiers. Such "SASL application protocols" SHOULD delay any
case mapping of authorization identifiers to the last possible case mapping of authorization identifiers to the last possible
moment, which happens to necessarily be on the server side (this moment, which happens to necessarily be on the server side (this
enables decisions about case mapping to be a matter of deployment enables decisions about case mapping to be a matter of deployment
policy). In keeping with [RFC4422], SASL application protocols policy). In keeping with [RFC4422], SASL application protocols
are not to apply this or any other profile to authentication are not to apply this or any other profile to authentication
identifiers. identifiers.
o Application protocols that do not use SASL (such as HTTP o Application protocols that do not use SASL (such as HTTP
authentication with the Basic and Digest schemes [RFC2617]) MUST authentication with the Basic and Digest schemes [RFC2617] /
specify whether and when case mapping is to be applied to [I-D.ietf-httpauth-basicauth-update] / [I-D.ietf-httpauth-digest])
MUST specify whether and when case mapping is to be applied to
authentication identifiers and authorization identifiers. Such authentication identifiers and authorization identifiers. Such
"non-SASL application protocols" SHOULD delay any case mapping to "non-SASL application protocols" SHOULD delay any case mapping to
the last possible moment, such as when doing a lookup by username, the last possible moment, such as when doing a lookup by username,
username comparisons, or generating a cryptographic salt from a username comparisons, or generating a cryptographic salt from a
username (if the last possible moment happens on the server, then username (if the last possible moment happens on the server, then
decisions about case mapping can be a matter of deployment decisions about case mapping can be a matter of deployment
policy). policy).
If the specification for a SASL mechanism, SASL application protocol, If the specification for a SASL mechanism, SASL application protocol,
or non-SASL application protocol specifies the handling of case or non-SASL application protocol specifies the handling of case
mapping for strings that conform to the UsernameIdentifierClass, it mapping for strings that conform to the UsernameIdentifierClass, it
MUST clearly describe whether case mapping is required, recommended, MUST clearly describe whether case mapping is required, recommended,
or optional at the level of the protocol itself, implementations or optional at the level of the protocol itself, implementations
thereof, or service deployments. thereof, or service deployments.
3.6. Application-Layer Constructs Informational Note: The LocalpartIdentifierClass profile defined
in [I-D.ietf-xmpp-6122bis] is identical to the
UsernameIdentifierClass profile defined here, except that the
LocalpartIdentifierClass profile specifies case mapping.
3.4. Application-Layer Constructs
The username rule allows an application protocol, implementation, or The username rule allows an application protocol, implementation, or
deployment to create application-layer constructs such as deployment to create application-layer constructs such as
"user@domain" or "Firstname Middlename Lastname" (e.g., because the "user@domain" or "Firstname Middlename Lastname" (e.g., because the
PRECIS IdentifierClass allows any ASCII7 character, because spaces PRECIS IdentifierClass allows any ASCII7 character, because spaces
can be used to separate userpart instances, and because domain names can be used to separate userpart instances, and because domain names
as specified in [RFC5890] and [RFC5892] are a subset of the PRECIS as specified in [RFC5890] and [RFC5892] are a subset of the PRECIS
IdentifierClass). IdentifierClass).
3.7. Examples 3.5. Examples
The following examples illustrate a small number of userparts (not The following examples illustrate a small number of userparts (not
usernames) that are consistent with the format defined above (note usernames) that are consistent with the format defined above (note
that the characters < and > are used here to delineate the actual that the characters < and > are used here to delineate the actual
userparts and are not part of the userpart strings). userparts and are not part of the userpart strings).
Table 1: A sample of legal userparts Table 1: A sample of legal userparts
+--------------------------+---------------------------------+ +--------------------------+---------------------------------+
| # | Userpart | Notes | | # | Userpart | Notes |
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U+00DF) can mostly be used interchangeably with the two characters U+00DF) can mostly be used interchangeably with the two characters
"ss", the userparts in these examples are different and (if desired) "ss", the userparts in these examples are different and (if desired)
a server would need to enforce a registration policy that disallows a server would need to enforce a registration policy that disallows
one of them if the other is registered. Regarding examples 5, 6, and one of them if the other is registered. Regarding examples 5, 6, and
7: optional case-mapping of GREEK CAPITAL LETTER SIGMA (U+03A3) to 7: optional case-mapping of GREEK CAPITAL LETTER SIGMA (U+03A3) to
lowercase (i.e., to GREEK SMALL LETTER SIGMA, U+03C3) during lowercase (i.e., to GREEK SMALL LETTER SIGMA, U+03C3) during
comparison would result in matching the userparts in examples 5 and comparison would result in matching the userparts in examples 5 and
6; however, because the PRECIS mapping rules do not account for the 6; however, because the PRECIS mapping rules do not account for the
special status of GREEK SMALL LETTER FINAL SIGMA (U+03C2), the special status of GREEK SMALL LETTER FINAL SIGMA (U+03C2), the
userparts in examples 5 and 7 or examples 6 and 7 would not be userparts in examples 5 and 7 or examples 6 and 7 would not be
matched. matched during comparison.
The following examples illustrate strings that are not valid The following examples illustrate strings that are not valid
userparts (not usernames) because they violate the format defined userparts (not usernames) because they violate the format defined
above. above.
Table 2: A sample of strings that violate the userpart rule Table 2: A sample of strings that violate the userpart rule
+--------------------------+---------------------------------+ +--------------------------+---------------------------------+
| # | Non-Userpart string | Notes | | # | Non-Userpart string | Notes |
+--------------------------+---------------------------------+ +--------------------------+---------------------------------+
skipping to change at page 9, line 33 skipping to change at page 9, line 33
the Unicode character ROMAN NUMERAL FOUR (U+2163) has a compatibility the Unicode character ROMAN NUMERAL FOUR (U+2163) has a compatibility
equivalent of the string formed of LATIN CAPITAL LETTER I (U+0049) equivalent of the string formed of LATIN CAPITAL LETTER I (U+0049)
and LATIN CAPITAL LETTER V (U+0056), but characters with and LATIN CAPITAL LETTER V (U+0056), but characters with
compatibility equivalents are not allowed in the PRECIS compatibility equivalents are not allowed in the PRECIS
IdentiferClass. Regarding example 11: symbol characters such as IdentiferClass. Regarding example 11: symbol characters such as
BLACK CHESS KING (U+265A) are not allowed in the PRECIS BLACK CHESS KING (U+265A) are not allowed in the PRECIS
IdentifierClass. IdentifierClass.
4. Passwords 4. Passwords
Detailed rules for the preparation, enforcement, and comparision of
passwords are provided in the following sections (on the distinction
between these actions, refer to [I-D.ietf-precis-framework]).
4.1. Definition 4.1. Definition
This document specifies that a password is a string of Unicode code This document specifies that a password is a string of Unicode code
points [UNICODE], encoded using UTF-8 [RFC3629], and conformant to points [UNICODE], encoded using UTF-8 [RFC3629], and conformant to
the PRECIS FreeformClass. the PRECIS FreeformClass.
The syntax for a password is defined as follows using the Augmented The syntax for a password is defined as follows using the Augmented
Backus-Naur Form (ABNF) [RFC5234]. Backus-Naur Form (ABNF) [RFC5234].
password = 1*(freepoint) password = 1*(freebyte)
; ;
; a "freepoint" is a UTF-8 encoded ; a "freebyte" is a byte used to represent a
; Unicode code point that conforms to ; UTF-8 encoded Unicode code point that can be
; the PRECIS "FreeformClass" ; contained in a string that conforms to the
; ; PRECIS "FreefromClass"
;
All code points and blocks not explicitly allowed in the PRECIS All code points and blocks not explicitly allowed in the PRECIS
FreeformClass are disallowed; this includes private use characters, FreeformClass are disallowed; this includes private use characters,
surrogate code points, and the other code points and blocks defined surrogate code points, and the other code points and blocks defined
as "Prohibited Output" in Section 2.3 of RFC 4013. as "Prohibited Output" in Section 2.3 of RFC 4013.
A password MUST NOT be zero bytes in length. This rule is to be A password MUST NOT be zero bytes in length. This rule is to be
enforced after any normalization and mapping of code points. enforced after any normalization and mapping of code points.
Note: The prohibition on zero-length passwords is not a
recommendation regarding password strength (since a password of
only one byte is highly insecure), but is meant to prevent
applications from omitting a password entirely.
In protocols that provide passwords as input to a cryptographic In protocols that provide passwords as input to a cryptographic
algorithm such as a hash function, the client will need to perform algorithm such as a hash function, the client will need to perform
proper preparation of the password before applying the algorithm, proper preparation of the password before applying the algorithm,
since the password is not available to the server in plaintext form. since the password is not available to the server in plaintext form.
4.2. Preparation 4.2. PasswordFreeformClass Profile
The definition of the PasswordFreeformClass profile is provided in
the following sections, including detailed information about
preparation, enforcement, and comparison (on the distinction between
these actions, refer to [I-D.ietf-precis-framework]).
4.2.1. Preparation
An entity that prepares a string for inclusion in a password slot An entity that prepares a string for inclusion in a password slot
MUST ensure that the string consists only of Unicode code points that MUST ensure that the string consists only of Unicode code points that
conform to the "FreeformClass" base string class defined in conform to the "FreeformClass" base string class defined in
[I-D.ietf-precis-framework]. In addition, the string MUST be encoded [I-D.ietf-precis-framework]. In addition, the string MUST be encoded
as UTF-8 [RFC3629]. as UTF-8 [RFC3629].
4.3. Enforcement 4.2.2. Enforcement
An entity that performs enforcement in password slots MUST prepare a An entity that performs enforcement in password slots MUST prepare a
string as described in the previous section and MUST also apply the string as described in the previous section and MUST also apply the
rules specified below for the PasswordFreeformClass (these rules MUST rules specified below for the PasswordFreeformClass (these rules MUST
be applied in the order shown). be applied in the order shown).
1. Width Mapping Rule: Fullwidth and halfwidth characters MUST NOT 1. Width Mapping Rule: Fullwidth and halfwidth characters MUST NOT
be mapped to their decomposition mappings. be mapped to their decomposition mappings.
2. Additional Mapping Rule: Any instances of non-ASCII space MUST be 2. Additional Mapping Rule: Any instances of non-ASCII space MUST be
mapped to ASCII space (U+0020); such an instance is any Unicode mapped to ASCII space (U+0020); a non-ASCII space is any Unicode
code point that has a compatibility mapping of any kind to U+0020 code point having a general category of "Zs", naturally with the
SPACE (including but not limited to <compat> as for U+0384 GREEK exception of U+0020.
TONOS, <noBreak> as for U+2007 FIGURE SPACE, and <wide> as for
U+3000 IDEOGRAPHIC SPACE).
3. Case Mapping Rule: Uppercase and titlecase characters MUST NOT be 3. Case Mapping Rule: Uppercase and titlecase characters MUST NOT be
mapped to their lowercase equivalents. mapped to their lowercase equivalents.
4. Normalization Rule: Unicode Normalization Form C (NFC) MUST be 4. Normalization Rule: Unicode Normalization Form C (NFC) MUST be
applied to all characters. applied to all characters.
5. Exclusion Rule: There is no exclusion rule. 5. Directionality Rule: There is no directionality rule. The "Bidi
6. Directionality Rule: There is no directionality rule. The "Bidi
Rule" (defined in [RFC5893]) and similar rules are unnecessary Rule" (defined in [RFC5893]) and similar rules are unnecessary
and inapplicable to passwords, since they can reduce the range of and inapplicable to passwords, since they can reduce the range of
characters that are allowed in a string and therefore reduce the characters that are allowed in a string and therefore reduce the
amount of entropy that is possible in a password. Furthermore, amount of entropy that is possible in a password. Furthermore,
such rules are intended to minimize the possibility that the same such rules are intended to minimize the possibility that the same
string will be displayed differently on a system set for right- string will be displayed differently on a system set for right-
to-left display and a system set for left-to-right display; to-left display and a system set for left-to-right display;
however, passwords are typically not displayed at all and are however, passwords are typically not displayed at all and are
rarely meant to be interoperable across different systems in the rarely meant to be interoperable across different systems in the
way that non-secret strings like domain names and usernames are. way that non-secret strings like domain names and usernames are.
4.4. Comparison 4.2.3. Comparison
An entity that performs comparison of two strings before or after An entity that performs comparison of two strings before or after
their inclusion in password slots MUST prepare each string and their inclusion in password slots MUST prepare each string and
enforce the rules specified in the previous two sections. The two enforce the rules specified in the previous two sections. The two
strings are to be considered equivalent if they are an exact octet- strings are to be considered equivalent if they are an exact octet-
for-octet match (sometimes called "bit-string identity"). for-octet match (sometimes called "bit-string identity").
4.5. Examples 4.3. Examples
The following examples illustrate a small number of passwords that The following examples illustrate a small number of passwords that
are consistent with the format defined above (note that the are consistent with the format defined above (note that the
characters < and > are used here to delineate the actual passwords characters < and > are used here to delineate the actual passwords
and are not part of the username strings). and are not part of the password strings).
Table 3: A sample of legal passwords Table 3: A sample of legal passwords
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| # | Password | Notes | | # | Password | Notes |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| 13| <correct horse battery staple> | ASCII space is allowed | | 12| <correct horse battery staple> | ASCII space is allowed |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| 14| <Correct Horse Battery Staple> | | | 13| <Correct Horse Battery Staple> | Different from example 12 |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| 15| <&#x3C0;&#xDF;&#xE5;> | Non-ASCII letters are OK | | 14| <&#x3C0;&#xDF;&#xE5;> | Non-ASCII letters are OK |
| | | (e.g., GREEK SMALL LETTER | | | | (e.g., GREEK SMALL LETTER |
| | | PI, U+03C0) | | | | PI, U+03C0) |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| 16| <Jack of &#x2666;s> | Symbols are OK (e.g., BLACK | | 15| <Jack of &#x2666;s> | Symbols are OK (e.g., BLACK |
| | | DIAMOND SUIT, U+2666) | | | | DIAMOND SUIT, U+2666) |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
The following examples illustrate strings that are not valid The following examples illustrate strings that are not valid
passwords because they violate the format defined above. passwords because they violate the format defined above.
Table 4: A sample of strings that violate the password rules Table 4: A sample of strings that violate the password rules
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| # | Password | Notes | | # | Password | Notes |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| 17| <foo&#x1680;bar> | Non-ASCII space (here, OGHAM | | 16| <foo&#x1680;bar> | Non-ASCII space (here, OGHAM |
| | | SPACE MARK, U+1680) is not | | | | SPACE MARK, U+1680) is not |
| | | allowed | | | | allowed |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
| 18| <my cat is a &#x9;by> | Controls are disallowed | | 17| <my cat is a &#x9;by> | Controls are disallowed |
+------------------------------------+------------------------------+ +------------------------------------+------------------------------+
5. Migration 5. Migration
The rules defined in this specification differ slightly from those The rules defined in this specification differ slightly from those
defined by the SASLprep specification [RFC4013]. The following defined by the SASLprep specification [RFC4013]. The following
sections describe these differences, along with their implications sections describe these differences, along with their implications
for migration, in more detail. for migration, in more detail.
5.1. Usernames 5.1. Usernames
Deployments that currently use SASLprep for handling usernames might Deployments that currently use SASLprep for handling usernames might
need to scrub existing data when migrating to use of the rules need to scrub existing data when migrating to use of the rules
defined in this specification. In particular: defined in this specification. In particular:
o SASLprep specified the use of Unicode Normalization Form KC o SASLprep specified the use of Unicode Normalization Form KC
(NFKC), whereas this usage of the PRECIS IdentifierClass employs (NFKC), whereas the UsernameIdentifierClass profile employs
Unicode Normalization Form C (NFC). In practice this change is Unicode Normalization Form C (NFC). In practice this change is
unlikely to cause significant problems, because NFKC provides unlikely to cause significant problems, because NFKC provides
methods for mapping Unicode code points with compatibility methods for mapping Unicode code points with compatibility
equivalents to those equivalents, whereas the PRECIS equivalents to those equivalents, whereas the PRECIS
IdentifierClass entirely disallows Unicode code points with IdentifierClass entirely disallows Unicode code points with
compatibility equivalents (i.e., during comparison NFKC is more compatibility equivalents (i.e., during comparison NFKC is more
"aggressive" about finding matches than is NFC). A few examples "aggressive" about finding matches than NFC). A few examples
might suffice to indicate the nature of the problem: (1) U+017F might suffice to indicate the nature of the problem:
LATIN SMALL LETTER LONG S is compatibility equivalent to U+0073
LATIN SMALL LETTER S (2) U+2163 ROMAN NUMERAL FOUR is 1. U+017F LATIN SMALL LETTER LONG S is compatibility equivalent
compatibility equivalent to U+0049 LATIN CAPITAL LETTER I and to U+0073 LATIN SMALL LETTER S
U+0056 LATIN CAPITAL LETTER V (3) U+FB01 LATIN SMALL LIGATURE FI
is compatibility equivalent to U+0066 LATIN SMALL LETTER F and 2. U+2163 ROMAN NUMERAL FOUR is compatibility equivalent to
U+0069 LATIN SMALL LETTER I. Under SASLprep, the use of NFKC also U+0049 LATIN CAPITAL LETTER I and U+0056 LATIN CAPITAL LETTER
handled the mapping of fullwidth and halfwidth code points to V
their decomposition mappings. Although it is expected that code
points with compatibility equivalents are rare in existing 3. U+FB01 LATIN SMALL LIGATURE FI is compatibility equivalent to
usernames, for migration purposes deployments might want to search U+0066 LATIN SMALL LETTER F and U+0069 LATIN SMALL LETTER I
their database of usernames for Unicode code points with
compatibility equivalents and map those code points to their Under SASLprep, the use of NFKC also handled the mapping of
compatibility equivalents. fullwidth and halfwidth code points to their decomposition
mappings. Although it is expected that code points with
compatibility equivalents are rare in existing usernames, for
migration purposes deployments might want to search their database
of usernames for Unicode code points with compatibility
equivalents and map those code points to their compatibility
equivalents.
o SASLprep mapped the "characters commonly mapped to nothing" from o SASLprep mapped the "characters commonly mapped to nothing" from
Appendix B.1 of [RFC3454]) to nothing, whereas the PRECIS Appendix B.1 of [RFC3454]) to nothing, whereas the PRECIS
IdentifierClass entirely disallows most of these characters, which IdentifierClass entirely disallows most of these characters, which
correspond to the code points from the "M" category defined under correspond to the code points from the "M" category defined under
Section 6.13 of [I-D.ietf-precis-framework] (with the exception of Section 8.13 of [I-D.ietf-precis-framework] (with the exception of
U+1806 MONGOLIAN TODO SOFT HYPHEN, which was "commonly mapped to U+1806 MONGOLIAN TODO SOFT HYPHEN, which was "commonly mapped to
nothing" in Unicode 3.2 but at the time of this writing does not nothing" in Unicode 3.2 but at the time of this writing does not
have a derived property of Default_Ignorable_Code_Point in Unicode have a derived property of Default_Ignorable_Code_Point in Unicode
6.2). For migration purposes, deployments might want to remove 7.0). For migration purposes, deployments might want to remove
code points contained in the PRECIS "M" category from usernames. code points contained in the PRECIS "M" category from usernames.
o SASLprep allowed uppercase and titlecase characters, whereas this o SASLprep allowed uppercase and titlecase characters, whereas the
usage of the PRECIS IdentifierClass maps uppercase and titlecase UsernameIdentifierClass profile maps uppercase and titlecase
characters to their lowercase equivalents. For migration characters to their lowercase equivalents. For migration
purposes, deployments can either convert uppercase and titlecase purposes, deployments can either convert uppercase and titlecase
characters to their lowercase equivalents in usernames (thus characters to their lowercase equivalents in usernames (thus
losing the case information) or preserve uppercase and titlecase losing the case information) or preserve uppercase and titlecase
characters and ignore the case difference when comparing characters and ignore the case difference when comparing
usernames. usernames.
5.2. Passwords 5.2. Passwords
Depending on local service policy, migration from RFC 4013 to this Depending on local service policy, migration from RFC 4013 to this
specification might not involve any scrubbing of data (since specification might not involve any scrubbing of data (since
passwords might not be stored in the clear anyway); however, service passwords might not be stored in the clear anyway); however, service
providers need to be aware of possible issues that might arise during providers need to be aware of possible issues that might arise during
migration. In particular: migration. In particular:
o SASLprep specified the use of Unicode Normalization Form KC o SASLprep specified the use of Unicode Normalization Form KC
(NFKC), whereas this usage of the PRECIS FreeformClass employs (NFKC), whereas the PasswordFreeformClass profile employs Unicode
Unicode Normalization Form C (NFC). Because NFKC is more Normalization Form C (NFC). Because NFKC is more aggressive about
aggressive about finding matches than NFC, in practice this change finding matches than NFC, in practice this change is unlikely to
is unlikely to cause significant problems and indeed has the cause significant problems and indeed has the security benefit of
security benefit of probably resulting in fewer false positives probably resulting in fewer false positives when comparing
when comparing passwords. A few examples might suffice to passwords. A few examples might suffice to indicate the nature of
indicate the nature of the problem: (1) U+017F LATIN SMALL LETTER the problem:
LONG S is compatibility equivalent to U+0073 LATIN SMALL LETTER S
(2) U+2163 ROMAN NUMERAL FOUR is compatibility equivalent to 1. U+017F LATIN SMALL LETTER LONG S is compatibility equivalent
U+0049 LATIN CAPITAL LETTER I and U+0056 LATIN CAPITAL LETTER V to U+0073 LATIN SMALL LETTER S
(3) U+FB01 LATIN SMALL LIGATURE FI is compatibility equivalent to
U+0066 LATIN SMALL LETTER F and U+0069 LATIN SMALL LETTER I. 2. U+2163 ROMAN NUMERAL FOUR is compatibility equivalent to
U+0049 LATIN CAPITAL LETTER I and U+0056 LATIN CAPITAL LETTER
V
3. U+FB01 LATIN SMALL LIGATURE FI is compatibility equivalent to
U+0066 LATIN SMALL LETTER F and U+0069 LATIN SMALL LETTER I
Under SASLprep, the use of NFKC also handled the mapping of Under SASLprep, the use of NFKC also handled the mapping of
fullwidth and halfwidth code points to their decomposition fullwidth and halfwidth code points to their decomposition
mappings. Although it is expected that code points with mappings. Although it is expected that code points with
compatibility equivalents are rare in existing passwords, some compatibility equivalents are rare in existing passwords, some
passwords that matched when SASLprep was used might no longer work passwords that matched when SASLprep was used might no longer work
when the rules in this specification are applied. when the rules in this specification are applied.
o SASLprep mapped the "characters commonly mapped to nothing" from o SASLprep mapped the "characters commonly mapped to nothing" from
Appendix B.1 of [RFC3454]) to nothing, whereas the PRECIS Appendix B.1 of [RFC3454]) to nothing, whereas the PRECIS
FreeformClass entirely disallows such characters, which correspond FreeformClass entirely disallows such characters, which correspond
to the code points from the "M" category defined under to the code points from the "M" category defined under
Section 6.13 of [I-D.ietf-precis-framework] (with the exception of Section 8.13 of [I-D.ietf-precis-framework] (with the exception of
U+1806 MONGOLIAN TODO SOFT HYPHEN, which was commonly mapped to U+1806 MONGOLIAN TODO SOFT HYPHEN, which was commonly mapped to
nothing in Unicode 3.2 but at the time of this writing is allowed nothing in Unicode 3.2 but at the time of this writing is allowed
by Unicode 6.2). In practice, this change will probably have no by Unicode 7.0). In practice, this change will probably have no
effect on comparison, but user-oriented software might reject such effect on comparison, but user-oriented software might reject such
code points instead of ignoring them during password preparation. code points instead of ignoring them during password preparation.
6. IANA Considerations 6. IANA Considerations
The IANA shall add the following entries to the PRECIS Profiles The IANA shall add the following entries to the PRECIS Profiles
Registry. Registry.
6.1. UsernameIdentifierClass 6.1. UsernameIdentifierClass Profile
Name: UsernameIdentifierClass. Name: UsernameIdentifierClass.
Applicability: Usernames in security and application protocols. Applicability: Usernames in security and application protocols.
Base Class: IdentifierClass. Base Class: IdentifierClass.
Replaces: The SASLprep profile of Stringprep. Replaces: The SASLprep profile of Stringprep.
Width Mapping Rule: Map fullwidth and halfwidth characters to their Width Mapping Rule: Map fullwidth and halfwidth characters to their
decomposition mappings. decomposition mappings.
Additional Mapping Rule: None. Additional Mapping Rule: None.
Case Mapping Rule: To be defined by security or application Case Mapping Rule: To be defined by security or application
protocols that use this profile. protocols that use this profile.
Normalization Rule: NFC. Normalization Rule: NFC.
Exclusion Rule: None.
Directionality Rule: The "Bidi Rule" defined in RFC 5893 applies. Directionality Rule: The "Bidi Rule" defined in RFC 5893 applies.
Enforcement: To be defined by security or application protocols that Enforcement: To be defined by security or application protocols that
use this profile. use this profile.
Specification: RFC XXXX. [Note to RFC Editor: please change XXXX to Specification: RFC XXXX. [Note to RFC Editor: please change XXXX to
the number issued for this specification.] the number issued for this specification.]
6.2. PasswordFreeformClass 6.2. PasswordFreeformClass Profile
Name: PasswordFreeformClass. Name: PasswordFreeformClass.
Applicability: Passwords in security and application protocols. Applicability: Passwords in security and application protocols.
Base Class: FreeformClass Base Class: FreeformClass
Replaces: The SASLprep profile of Stringprep. Replaces: The SASLprep profile of Stringprep.
Width Mapping Rule: None. Width Mapping Rule: None.
Additional Mapping Rule: Map non-ASCII space characters to ASCII Additional Mapping Rule: Map non-ASCII space characters to ASCII
space. space.
Case Mapping Rule: None. Case Mapping Rule: None.
Normalization Rule: NFC. Normalization Rule: NFC.
Exclusion Rule: None.
Directionality Rule: None. Directionality Rule: None.
Enforcement: To be defined by security or application protocols that Enforcement: To be defined by security or application protocols that
use this profile. use this profile.
Specification: RFC XXXX. [Note to RFC Editor: please change XXXX to Specification: RFC XXXX. [Note to RFC Editor: please change XXXX to
the number issued for this specification.] the number issued for this specification.]
7. Security Considerations 7. Security Considerations
skipping to change at page 16, line 24 skipping to change at page 16, line 32
The security considerations described in [UTS39] apply to the use of The security considerations described in [UTS39] apply to the use of
Unicode characters in usernames and passwords. Unicode characters in usernames and passwords.
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-precis-framework] [I-D.ietf-precis-framework]
Saint-Andre, P. and M. Blanchet, "Precis Framework: Saint-Andre, P. and M. Blanchet, "Precis Framework:
Handling Internationalized Strings in Protocols", draft- Handling Internationalized Strings in Protocols", draft-
ietf-precis-framework-19 (work in progress), October 2014. ietf-precis-framework-20 (work in progress), November
2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003. 10646", STD 63, RFC 3629, November 2003.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[UNICODE] The Unicode Consortium, "The Unicode Standard, Version [UNICODE] The Unicode Consortium, "The Unicode Standard, Version
6.3", 2013, 6.3", 2013,
<http://www.unicode.org/versions/Unicode6.3.0/>. <http://www.unicode.org/versions/Unicode6.3.0/>.
8.2. Informative References 8.2. Informative References
[I-D.ietf-httpauth-basicauth-update]
Reschke, J., "The 'Basic' HTTP Authentication Scheme",
draft-ietf-httpauth-basicauth-update-02 (work in
progress), October 2014.
[I-D.ietf-httpauth-digest]
Shekh-Yusef, R., Ahrens, D., and S. Bremer, "HTTP Digest
Access Authentication", draft-ietf-httpauth-digest-08
(work in progress), August 2014.
[I-D.ietf-xmpp-6122bis]
Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Address Format", draft-ietf-xmpp-
6122bis-16 (work in progress), November 2014.
[RFC20] Cerf, V., "ASCII format for network interchange", RFC 20, [RFC20] Cerf, V., "ASCII format for network interchange", RFC 20,
October 1969. October 1969.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication", Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999. RFC 2617, June 1999.
[RFC3454] Hoffman, P. and M. Blanchet, "Preparation of [RFC3454] Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ("stringprep")", RFC 3454, Internationalized Strings ("stringprep")", RFC 3454,
skipping to change at page 18, line 42 skipping to change at page 19, line 19
o As recommended in the PRECIS framework, changed the Unicode o As recommended in the PRECIS framework, changed the Unicode
normalization form from NFKC to NFC. normalization form from NFKC to NFC.
o Some Unicode code points that were mapped to nothing in RFC 4013 o Some Unicode code points that were mapped to nothing in RFC 4013
are simply disallowed by PRECIS. are simply disallowed by PRECIS.
Appendix B. Acknowledgements Appendix B. Acknowledgements
The following individuals provided helpful feedback on this document: The following individuals provided helpful feedback on this document:
Marc Blanchet, Alan DeKok, Joe Hildebrand, Jeffrey Hutzelman, Simon Marc Blanchet, Alan DeKok, Joe Hildebrand, Jeffrey Hutzelman, Simon
Josefsson, Jonathan Lennox, Matt Miller, Chris Newman, Yutaka OIWA, Josefsson, Jonathan Lennox, James Manger, Matt Miller, Chris Newman,
Pete Resnick, Andrew Sullivan, and Nico Williams. Nico in particular Yutaka OIWA, Pete Resnick, Andrew Sullivan, and Nico Williams. Nico
deserves special recognition for providing text that was used in in particular deserves special recognition for providing text that
Section 3.5. Thanks also to Yoshiro YONEYA and Takahiro NEMOTO for was used in Section 3.3. Thanks also to Yoshiro YONEYA and Takahiro
implementation feedback. NEMOTO for implementation feedback.
This document borrows some text from [RFC4013] and [RFC6120]. This document borrows some text from [RFC4013] and [RFC6120].
Peter Saint-Andre wishes to acknowledge Cisco Systems, Inc., for
employing him during his work on earlier versions of this document.
Authors' Addresses Authors' Addresses
Peter Saint-Andre Peter Saint-Andre
&yet &yet
Email: peter@andyet.com Email: peter@andyet.com
URI: https://andyet.com/ URI: https://andyet.com/
Alexey Melnikov Alexey Melnikov
Isode Ltd Isode Ltd
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