[idn] stringprep: existing profiles and string processing complexity
Erik van der Poel <erik@vanderpoel.org> Fri, 18 March 2005 19:39 UTC
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Date: Fri, 18 Mar 2005 11:33:27 -0800
From: Erik van der Poel <erik@vanderpoel.org>
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To: Simon Josefsson <jas@extundo.com>
CC: idn@ops.ietf.org
Subject: [idn] stringprep: existing profiles and string processing complexity
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Simon Josefsson wrote: > The issue should be handled in an update of the StringPrep. If the > PR-29 fix is incorporated, there must a good transition discussion in > the document. The problem cannot only be discussed in the realm of > IDNA, since StringPrep is used for other purposes as well. For me, > the most important use is SASLprep, because it is used to prepare > username and passwords. Hence, it is used in security critical > application, where the requirements are different than from IDNA. The > discussion must be wider than for only IDNA. I downloaded all the RFCs and Internet Drafts and grepped for Stringprep. Some of the profiles specified in RFCs are not registered at IANA. There are 3 profiles in an NFS4 spec (RFC 3530) that have not been registered. It is not clear to me that profiles must be registered. I have started a table of profiles that shows which parts of Stringprep are being used. So far, I have only listed profiles found in RFCs (not Internet Drafts). This table was far easier to create in an HTML editor, and I didn't want to send HTML to this list, so it's on my Web site: http://nameprep.org/stringprep.html It's still rough and doesn't indicate all the details, but it's a start. As I read the profiles and text in their vicinity, it seems as though some may not be fully aware of some of the complexities of string processing in Unicode. (This is not a flaw in Unicode. There are various written languages in the world, and some of them have complex rules.) For example, RFC 3530 says: If the case_preserving attribute is present and set to false, then the NFS version 4 server MUST use table B.2 to map case when processing utf8str_cs strings. Whether the server maps from lower to upper case or the upper to lower case is an implementation dependency. Stringprep's case mapping table is intended to be used only to map upper case to lower case. For example, here is a special case: 00DF; 0073 0073; Case map You can't really use this entry to go "backwards". There are other RFCs and Internet Drafts with various issues like this, or that are so vague as to make you wonder whether interoperability is truly assured. The IETF community is of course full of networking experts, and the Unicode community is full of internationalization experts. Stringprep finds itself in the rather special position of being wedged between networking (specifically, string input and matching) and Unicode. It might be a good idea to collect the issues and try to increase understanding of international string processing among networking community members. Erik
- [idn] related work Erik van der Poel
- [idn] Unicode categories Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue JFC (Jefsey) Morfin
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue John C Klensin
- Re: [idn] nameprep2 and the slash homograph issue Adam M. Costello
- Re: [idn] something a little lighter for the week… Doug Ewell
- Re: [idn] stability Erik van der Poel
- Re: [idn] Re: character tables Erik van der Poel
- Re: [idn] Re: process Adam M. Costello
- Re: [idn] punctuation John C Klensin
- Re: [idn] Re: stability JFC (Jefsey) Morfin
- Re: [idn] Re: character tables Gervase Markham
- Re: [idn] stringprep: PRI #29 Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue Gervase Markham
- Re: [idn] Re: stability Erik van der Poel
- Re: [idn] process Paul Hoffman
- Re: [idn] Re: character tables YAO Jiankang
- Re: [idn] nameprep2 and the slash homograph issue JFC (Jefsey) Morfin
- Re: [idn] nameprep2 and the slash homograph issue Adam M. Costello
- Re: [idn] punctuation John C Klensin
- Re: [idn] punctuation tedd
- Re: [idn] Re: character tables JFC (Jefsey) Morfin
- Re: [idn] punctuation Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue Gervase Markham
- Re: [idn] Re: stability Erik van der Poel
- Re: [idn] Re: character tables Adam M. Costello
- [idn] Re: character tables John C Klensin
- Re: [idn] Re: character tables Erik van der Poel
- Re: [idn] Re: stability JFC (Jefsey) Morfin
- Re: [idn] Re: character tables Paul Hoffman
- Re: [idn] Re: stability Martin v. Löwis
- Re: [idn] Re: character tables Erik van der Poel
- Re: [idn] Re: stability John C Klensin
- [idn] Re: Unicode categories John C Klensin
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- [idn] character tables Erik van der Poel
- Re: [idn] Re: character tables John C Klensin
- Re: [idn] Re: stability Mark Davis
- Re: [idn] Re: stringprep: PRI #29 Erik van der Poel
- [idn] stability Erik van der Poel
- Re: [idn] Re: character tables Erik van der Poel
- Re: [idn] Re: dichotomies JFC (Jefsey) Morfin
- Re: [idn] process Adam M. Costello
- Re: [idn] Re: character tables William Tan
- Re: [idn] Re: process James Seng
- [idn] Re: stability Simon Josefsson
- Re: [idn] stability Erik van der Poel
- [idn] Re: stability Martin v. Löwis
- Re: [idn] Re: process Jaap Akkerhuis
- Re: [idn] Re: stringprep: PRI #29 Adam M. Costello
- Re: [idn] punctuation tedd
- [idn] Re: dichotomies Erik van der Poel
- Re: [idn] Re: stability Martin v. Löwis
- Re: [idn] punctuation Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] process JFC (Jefsey) Morfin
- [idn] Re: stability Simon Josefsson
- Re: [idn] nameprep2 and the slash homograph issue JFC (Jefsey) Morfin
- [idn] Re: stringprep: PRI #29 Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue Adam M. Costello
- Re: [idn] process John C Klensin
- Re: [idn] Re: Unicode categories Mark Davis
- Re: [idn] process Doug Ewell
- Re: [idn] Re: stability Adam M. Costello
- Re: [idn] process Erik van der Poel
- [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] punctuation tedd
- [idn] punctuation Erik van der Poel
- Re: [idn] Re: stability James Seng
- [idn] Re: stability Simon Josefsson
- [idn] something a little lighter for the weekend Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] something a little lighter for the week… Adam M. Costello
- Re: [idn] process Gervase Markham
- [idn] Re: character tables Cary Karp
- [idn] Mozilla? JFC (Jefsey) Morfin
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] punctuation Erik van der Poel
- [idn] Re: Unicode categories Erik van der Poel
- [idn] Re: stability Simon Josefsson
- Re: [idn] Re: character tables JFC (Jefsey) Morfin
- [idn] Re: process Stephane Bortzmeyer
- Re: [idn] process Erik van der Poel
- Re: [idn] punctuation Jaap Akkerhuis
- Re: [idn] Re: character tables Gervase Markham
- Re: [idn] Re: process Jaap Akkerhuis
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] Re: process James Seng
- [idn] stringprep mailing list Erik van der Poel
- Re: [idn] Re: dichotomies Erik van der Poel
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- Re: [idn] Re: stability Erik van der Poel
- Re: [idn] Re: character tables Erik van der Poel
- Re: [idn] Re: stability JFC (Jefsey) Morfin
- Re: [idn] Re: process Erik van der Poel
- [idn] Re: stringprep: PRI #29 Simon Josefsson
- Re: [idn] punctuation Erik van der Poel
- Re: [idn] stability Martin v. Löwis
- [idn] stringprep: PRI #29 Erik van der Poel
- Re: [idn] Re: character tables Paul Hoffman
- Re: [idn] nameprep2 and the slash homograph issue Erik van der Poel
- [idn] Re: stability Simon Josefsson
- [idn] process Erik van der Poel
- [idn] stringprep: existing profiles and string pr… Erik van der Poel
- Re: [idn] Re: stability Erik van der Poel
- [idn] dichotomies Erik van der Poel
- Re: [idn] stability JFC (Jefsey) Morfin
- [idn] Re: character tables Cary Karp
- Re: [idn] Re: process Erik van der Poel
- [idn] Re: stringprep mailing list Simon Josefsson
- Re: [idn] Re: Unicode categories Martin v. Löwis
- Re: [idn] Re: stability JFC (Jefsey) Morfin
- Re: [idn] something a little lighter for the week… John C Klensin
- Re: [idn] something a little lighter for the week… Adam M. Costello
- Re: [idn] Re: dichotomies JFC (Jefsey) Morfin
- Re: [idn] Re: stability Erik van der Poel
- Re: [idn] Re: stability Erik van der Poel
- [idn] Re: stringprep: PRI #29 Simon Josefsson
- Re: [idn] stability Erik van der Poel
- [idn] Re: stringprep: PRI #29 Simon Josefsson