Network Working Group P. Hoffman Request for Comments: 3491 IMC & VPNC Category: Standards Track M. Blanchet Viagenie March 2003 Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN) * Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. * Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. * Abstract > This document describes how to prepare internationalized domain name (IDN) labels in order to increase the likelihood that name input and name comparison work in ways that make sense for typical users throughout the world. This profile of the stringprep protocol is used as part of a suite of on-the-wire protocols for internationalizing the Domain Name System (DNS). この文書は、[[名前]]の[[入力]]と[[名前]]の[[比較]]が、 通常の世界中の利用者に意味のある形で行われる[[確からしさ]]を増加させるため、 どう[[国際化ドメイン名]] ([[IDN]]) [[名札]]を準備するかを説明します。 この [[stringprep]] [[プロトコル]]の[[プロファイル]]は、 [[ドメイン名システム]] ([[DNS]]) を[[国際化]]するために用いる[[プロトコル]]一式の一部として使われます。 * 1. Introduction This document specifies processing rules that will allow users to enter internationalized domain names (IDNs) into applications and have the highest chance of getting the content of the strings correct. It is a profile of stringprep [STRINGPREP]. These processing rules are only intended for internationalized domain names, not for arbitrary text. This profile defines the following, as required by [STRINGPREP]. - The intended applicability of the profile: internationalized domain names processed by IDNA. - The character repertoire that is the input and output to stringprep: Unicode 3.2, specified in section 2. - The mappings used: specified in section 3. - The Unicode normalization used: specified in section 4. - The characters that are prohibited as output: specified in section 5. - Bidirectional character handling: specified in section 6. ** 1.1 Interaction of protocol parts > Nameprep is used by the IDNA [IDNA] protocol for preparing domain names; it is not designed for any other purpose. It is explicitly not designed for processing arbitrary free text and SHOULD NOT be used for that purpose. Nameprep is a profile of Stringprep [STRINGPREP]. Implementations of Nameprep MUST fully implement Stringprep. [[Nameprep]] は、 [[IDNA]] [[プロトコル]]が[[ドメイン名]]を準備するために使います。 [[Nameprep]] は他の目的は考慮していません。 特に、任意の文章を処理する目的で設計してはおらず、 そのような目的で使う'''べきではありません'''。 [[Nameprep]] は [[Stringprep]] の[[プロファイル]]です。 [[Nameprep]] の実装者は [[Stringprep]] を完全に実装しなければ'''なりません'''。 > Nameprep is used to process domain name labels, not domain names. IDNA calls nameprep for each label in a domain name, not for the whole domain name. [[Nameprep]] は[[ドメイン名]]ではなく、[[ドメイン名札]]を処理するために使います。 [[IDNA]] は[[ドメイン名]]全体ではなく、[[ドメイン名]]中の[[名札]]それぞれについて [[Nameprep]] を呼びます。 ** 1.2 Terminology The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119]. * 2. Character Repertoire > This profile uses Unicode 3.2, as defined in [STRINGPREP] Appendix A. この[[プロファイル]]は、 [[Stringprep]] 附属書 A で定義されている通り、 [[Unicode 3.2]] を使います。 * 3. Mapping > This profile specifies mapping using the following tables from [STRINGPREP]: この[[プロファイル]]は、 [[Stringprep]] の次の表を使って[[写像]]を指定します。 > Table B.1 Table B.2 * 4. Normalization > This profile specifies using Unicode normalization form KC, as described in [STRINGPREP]. この[[プロファイル]]は、 [[Stringprep]] で説明されている通り、 [[Unicode]] [[正規化形]] KC を使うと指定します。 * 5. Prohibited Output > This profile specifies prohibiting using the following tables from [STRINGPREP]: この[[プロファイル]]は、 [[Stringprep]] の次の表を使って禁止を指定します。 > Table C.1.2 Table C.2.2 Table C.3 Table C.4 Table C.5 Table C.6 Table C.7 Table C.8 Table C.9 > IMPORTANT NOTE: This profile MUST be used with the IDNA protocol. The IDNA protocol has additional prohibitions that are checked outside of this profile. 重要な注意: この[[プロファイル]]は [[IDNA]] [[プロトコル]]と共に使わなければ'''なりません'''。 [[IDNA]] [[プロファイル]]にはこの[[プロファイル]]の他に更に検査する禁止事項があります。 * 6. Bidirectional characters > This profile specifies checking bidirectional strings as described in [STRINGPREP] section 6. この[[プロファイル]]は [[Stringprep]] 6章に説明されている[[双方向的]][[文字列]]の検査を指定します。 * 7. Unassigned Code Points in Internationalized Domain Names > If the processing in [IDNA] specifies that a list of unassigned code points be used, the system uses table A.1 from [STRINGPREP] as its list of unassigned code points. [[IDNA]] の処理で未割当て[[符号位置]]の一覧を使うと指定されている場合、 システムは未割当て[[符号位置]]の一覧として [[Stringprep]] の表 A.1 を使います。 *8. References **8.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [STRINGPREP] Hoffman, P. and M. Blanchet, "Preparation of Internationalized Strings ("stringprep")", RFC 3454, December 2002. [IDNA] Faltstrom, P., Hoffman, P. and A. Costello, "Internationalizing Domain Names in Applications (IDNA)", RFC 3490, March 2003. **8.2 Informative references [STD13] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, and "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. * 9. Security Considerations The Unicode and ISO/IEC 10646 repertoires have many characters that look similar. In many cases, users of security protocols might do visual matching, such as when comparing the names of trusted third parties. Because it is impossible to map similar-looking characters without a great deal of context such as knowing the fonts used, stringprep does nothing to map similar-looking characters together nor to prohibit some characters because they look like others. Security on the Internet partly relies on the DNS. Thus, any change to the characteristics of the DNS can change the security of much of the Internet. Domain names are used by users to connect to Internet servers. The security of the Internet would be compromised if a user entering a single internationalized name could be connected to different servers based on different interpretations of the internationalized domain name. Current applications might assume that the characters allowed in domain names will always be the same as they are in [STD13]. This document vastly increases the number of characters available in domain names. Every program that uses "special" characters in conjunction with domain names may be vulnerable to attack based on the new characters allowed by this specification. * 10. IANA Considerations This is a profile of stringprep. It has been registered by the IANA in the stringprep profile registry (www.iana.org/assignments/stringprep-profiles). Name of this profile: Nameprep RFC in which the profile is defined: This document. Indicator whether or not this is the newest version of the profile: This is the first version of Nameprep. * 11. Acknowledgements Many people from the IETF IDN Working Group and the Unicode Technical Committee contributed ideas that went into this document. The IDN Nameprep design team made many useful changes to the document. That team and its advisors include: Asmus Freytag Cathy Wissink Francois Yergeau James Seng Marc Blanchet Mark Davis Martin Duerst Patrik Faltstrom Paul Hoffman Additional significant improvements were proposed by: Jonathan Rosenne Kent Karlsson Scott Hollenbeck Dave Crocker Erik Nordmark Matitiahu Allouche * 12. Authors' Addresses Paul Hoffman Internet Mail Consortium and VPN Consortium 127 Segre Place Santa Cruz, CA 95060 USA EMail: paul.hoffman@imc.org and paul.hoffman@vpnc.org Marc Blanchet Viagenie inc. 2875 boul. Laurier, bur. 300 Ste-Foy, Quebec, Canada, G1V 2M2 EMail: Marc.Blanchet@viagenie.qc.ca * 13. Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. 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