draft-ietf-precis-7613bis-02.txt   draft-ietf-precis-7613bis-03.txt 
Network Working Group P. Saint-Andre Network Working Group P. Saint-Andre
Internet-Draft Filament Internet-Draft Filament
Obsoletes: 7613 (if approved) A. Melnikov Obsoletes: 7613 (if approved) A. Melnikov
Intended status: Standards Track Isode Ltd Intended status: Standards Track Isode Ltd
Expires: March 7, 2017 September 3, 2016 Expires: March 9, 2017 September 5, 2016
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-7613bis-02 draft-ietf-precis-7613bis-03
Abstract Abstract
This document describes updated methods for handling Unicode strings This document describes updated methods for handling Unicode strings
representing usernames and passwords. The previous approach was representing usernames and passwords. The previous approach was
known as SASLprep (RFC 4013) and was based on stringprep (RFC 3454). known as SASLprep (RFC 4013) and was based on stringprep (RFC 3454).
The methods specified in this document provide a more sustainable The methods specified in this document provide a more sustainable
approach to the handling of internationalized usernames and approach to the handling of internationalized usernames and
passwords. The preparation, enforcement, and comparison of passwords. The preparation, enforcement, and comparison of
internationalized strings (PRECIS) framework, RFC 7564, obsoletes RFC internationalized strings (PRECIS) framework, RFC 7564, obsoletes RFC
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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-
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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 March 7, 2017. This Internet-Draft will expire on March 9, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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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3.2. UsernameCaseMapped Profile . . . . . . . . . . . . . . . 6 3.2. UsernameCaseMapped Profile . . . . . . . . . . . . . . . 6
3.2.1. Rules . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2.1. Rules . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2.2. Preparation . . . . . . . . . . . . . . . . . . . . . 6 3.2.2. Preparation . . . . . . . . . . . . . . . . . . . . . 6
3.2.3. Enforcement . . . . . . . . . . . . . . . . . . . . . 7 3.2.3. Enforcement . . . . . . . . . . . . . . . . . . . . . 7
3.2.4. Comparison . . . . . . . . . . . . . . . . . . . . . 7 3.2.4. Comparison . . . . . . . . . . . . . . . . . . . . . 7
3.3. UsernameCasePreserved Profile . . . . . . . . . . . . . . 7 3.3. UsernameCasePreserved Profile . . . . . . . . . . . . . . 7
3.3.1. Rules . . . . . . . . . . . . . . . . . . . . . . . . 7 3.3.1. Rules . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3.2. Preparation . . . . . . . . . . . . . . . . . . . . . 8 3.3.2. Preparation . . . . . . . . . . . . . . . . . . . . . 8
3.3.3. Enforcement . . . . . . . . . . . . . . . . . . . . . 8 3.3.3. Enforcement . . . . . . . . . . . . . . . . . . . . . 8
3.3.4. Comparison . . . . . . . . . . . . . . . . . . . . . 8 3.3.4. Comparison . . . . . . . . . . . . . . . . . . . . . 8
3.4. Case Mapping vs. Case Preservation . . . . . . . . . . . 9 3.4. Case Mapping vs. Case Preservation . . . . . . . . . . . 8
3.5. Application-Layer Constructs . . . . . . . . . . . . . . 10 3.5. Application-Layer Constructs . . . . . . . . . . . . . . 10
3.6. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10 3.6. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1. Definition . . . . . . . . . . . . . . . . . . . . . . . 12 4.1. Definition . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. OpaqueString Profile . . . . . . . . . . . . . . . . . . 13 4.2. OpaqueString Profile . . . . . . . . . . . . . . . . . . 13
4.2.1. Preparation . . . . . . . . . . . . . . . . . . . . . 13 4.2.1. Preparation . . . . . . . . . . . . . . . . . . . . . 13
4.2.2. Enforcement . . . . . . . . . . . . . . . . . . . . . 14 4.2.2. Enforcement . . . . . . . . . . . . . . . . . . . . . 13
4.2.3. Comparison . . . . . . . . . . . . . . . . . . . . . 14 4.2.3. Comparison . . . . . . . . . . . . . . . . . . . . . 14
4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 14
5. Use in Application Protocols . . . . . . . . . . . . . . . . 15 5. Use in Application Protocols . . . . . . . . . . . . . . . . 15
6. Migration . . . . . . . . . . . . . . . . . . . . . . . . . . 16 6. Migration . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Usernames . . . . . . . . . . . . . . . . . . . . . . . . 16 6.1. Usernames . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. Passwords . . . . . . . . . . . . . . . . . . . . . . . . 17 6.2. Passwords . . . . . . . . . . . . . . . . . . . . . . . . 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7.1. UsernameCaseMapped Profile . . . . . . . . . . . . . . . 18 7.1. UsernameCaseMapped Profile . . . . . . . . . . . . . . . 18
7.2. UsernameCasePreserved Profile . . . . . . . . . . . . . . 19 7.2. UsernameCasePreserved Profile . . . . . . . . . . . . . . 19
7.3. OpaqueString Profile . . . . . . . . . . . . . . . . . . 20 7.3. OpaqueString Profile . . . . . . . . . . . . . . . . . . 20
7.4. Stringprep Profile . . . . . . . . . . . . . . . . . . . 20 7.4. Stringprep Profile . . . . . . . . . . . . . . . . . . . 20
8. Security Considerations . . . . . . . . . . . . . . . . . . . 20 8. Security Considerations . . . . . . . . . . . . . . . . . . . 20
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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
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 as an points [Unicode] that is structured as an ordered sequence of
ordered sequence of "userparts". A userpart is allowed to contain "userparts" and expressed in a standard Unicode Encoding Form (such
only code points that are in turn allowed by the PRECIS as UTF-8 [RFC3629]). A userpart is allowed to contain only code
IdentifierClass defined in Section 4.2 of [RFC7564], and thus points that are allowed by the PRECIS IdentifierClass defined in
consists almost exclusively of letters and digits. A username can Section 4.2 of [RFC7564], and thus consists almost exclusively of
consist of a single userpart or a space-separated sequence of letters and digits. A username can consist of a single userpart or a
userparts. space-separated sequence of userparts.
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*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 encode a
; UTF-8 encoded Unicode code point that can be ; Unicode code point that can be contained
; contained in a string that conforms to the ; in a string that conforms to the PRECIS
; PRECIS IdentifierClass ; 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,
surrogate code points, and the other code points and blocks that were surrogate code points, and the other code points and blocks that were
defined as "Prohibited Output" in [RFC4013]. In addition, common defined as "Prohibited Output" in [RFC4013]. In addition, common
constructions such as "user@example.com" (e.g., the Network Access constructions such as "user@example.com" (e.g., the Network Access
Identifier from [RFC7542]) are allowed as usernames under this Identifier from [RFC7542]) are allowed as usernames under this
specification, as they were under [RFC4013]. specification, as they were under [RFC4013].
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1. Apply the width-mapping rule specified in Section 3.2.1. It is 1. Apply the width-mapping rule specified in Section 3.2.1. It is
necessary to apply the rule at this point because otherwise the necessary to apply the rule at this point because otherwise the
PRECIS "HasCompat" category specified in Section 9.17 of PRECIS "HasCompat" category specified in Section 9.17 of
[RFC7564] would forbid fullwidth and halfwidth characters. [RFC7564] would forbid fullwidth and halfwidth characters.
2. Ensure that the string consists only of Unicode code points that 2. Ensure that the string consists only of Unicode code points that
conform to the PRECIS IdentifierClass defined in Section 4.2 of conform to the PRECIS IdentifierClass defined in Section 4.2 of
[RFC7564]. [RFC7564].
3. Encode the string as UTF-8 [RFC3629].
3.2.3. Enforcement 3.2.3. Enforcement
An entity that performs enforcement according to this profile MUST An entity that performs enforcement according to this profile MUST
prepare a string as described in Section 3.2.2 and MUST also apply prepare a string as described in Section 3.2.2 and MUST also apply
the following rules specified in Section 3.2.1 in the order shown: the following rules specified in Section 3.2.1 in the order shown:
1. Case-Mapping Rule 1. Case-Mapping Rule
2. Normalization Rule 2. Normalization Rule
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1. Apply the width-mapping rule specified in Section 3.2.1. It is 1. Apply the width-mapping rule specified in Section 3.2.1. It is
necessary to apply the rule at this point because otherwise the necessary to apply the rule at this point because otherwise the
PRECIS "HasCompat" category specified in Section 9.17 of PRECIS "HasCompat" category specified in Section 9.17 of
[RFC7564] would forbid fullwidth and halfwidth characters. [RFC7564] would forbid fullwidth and halfwidth characters.
2. Ensure that the string consists only of Unicode code points that 2. Ensure that the string consists only of Unicode code points that
conform to the PRECIS IdentifierClass defined in Section 4.2 of conform to the PRECIS IdentifierClass defined in Section 4.2 of
[RFC7564]. [RFC7564].
3. Encode the string as UTF-8 [RFC3629].
3.3.3. Enforcement 3.3.3. Enforcement
An entity that performs enforcement according to this profile MUST An entity that performs enforcement according to this profile MUST
prepare a string as described in Section 3.3.2 and MUST also apply prepare a string as described in Section 3.3.2 and MUST also apply
the following rules specified in Section 3.3.1 in the order shown: the following rules specified in Section 3.3.1 in the order shown:
1. Normalization Rule 1. Normalization Rule
2. Directionality Rule 2. Directionality Rule
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compatibility equivalents are not allowed in the PRECIS compatibility equivalents are not allowed in the PRECIS
IdentifierClass. Regarding example 11: symbol characters such as IdentifierClass. 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
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] that is conformant to the OpaqueString profile
the OpaqueString profile (specified below) of the PRECIS (specified below) of the PRECIS FreeformClass defined in Section 4.3
FreeformClass defined in Section 4.3 of [RFC7564]. of [RFC7564], and that is expressed in a standard Unicode Encoding
Form (such as UTF-8 [RFC3629]).
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*(freebyte) password = 1*(freebyte)
; ;
; a "freebyte" is a byte used to represent a ; a "freebyte" is a byte used to encode a
; UTF-8 encoded Unicode code point that can be ; Unicode code point that can be contained
; contained in a string that conforms to the ; in a string that conforms to the PRECIS
; PRECIS FreeformClass ; FreeformClass
; ;
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 (when corrected per as "Prohibited Output" in Section 2.3 of RFC 4013 (when corrected per
[Err1812]). [Err1812]).
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.
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The definition of the OpaqueString profile is provided in the The definition of the OpaqueString profile is provided in the
following sections, including detailed information about preparation, following sections, including detailed information about preparation,
enforcement, and comparison (for details on the distinction between enforcement, and comparison (for details on the distinction between
these actions, refer to [RFC7564]). these actions, refer to [RFC7564]).
4.2.1. Preparation 4.2.1. Preparation
An entity that prepares a string according to this profile MUST An entity that prepares a string according to this profile MUST
ensure that the string consists only of Unicode code points that ensure that the string consists only of Unicode code points that
conform to the FreeformClass base string class defined in [RFC7564]. conform to the FreeformClass base string class defined in [RFC7564].
In addition, the entity MUST encode the string as UTF-8 [RFC3629].
4.2.2. Enforcement 4.2.2. Enforcement
An entity that performs enforcement according to this profile MUST An entity that performs enforcement according to this profile MUST
prepare a string as described in Section 4.2.1 and MUST also apply prepare a string as described in Section 4.2.1 and MUST also apply
the rules specified below for the OpaqueString profile (these rules the rules specified below for the OpaqueString profile (these rules
MUST be applied in the order shown): MUST 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 (see Unicode Standard be mapped to their decomposition mappings (see Unicode Standard
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